Increased synthetic cytotoxicity of combinatorial chemo-radiotherapy in homologous recombination deficient tumors.

BACKGROUND: Homologous recombination deficient (HRD) tumors are exquisitely sensitive to platinum-based chemotherapy and when combined with RT, leads to improved overall survival in multiple cancer types. Whether a subset of tumors with distinct molecular characteristics demonstrate increased benefit from cisplatin and RT (c-RT) is unclear. We hypothesized that HRD tumors, whether associated with BRCA mutations or genomic scars of HRD, exhibit exquisite sensitivity to c-RT, and that HRD may be a significant driver of c-RT benefit. METHODS: Sensitivity to c-RT was examined using isogenic and sporadic breast cancer cell lines. HRD was assessed using four assays: RT-induced Rad51 foci, a DR-GFP reporter assay, a genomic scar (large scale state transitions, LST), and clonogenic survival assays (CSA). Whole genome sequencing of 4 breast tumors from a phase 2 clinical trial of neoadjuvant c-RT in triple negative breast cancer (TNBC) was performed and defined HRD utilizing HRDetect. RESULTS: BRCA1/2 deficient cell lines displayed functional HRD based on the Rad51 functional assay, with c-RT to RT or cisplatin interaction ratios (IR) of 1.11 and 26.84 for the BRCA1 isogenic pair at 2uM Cisplatin and 6Gy, respectively. The highest LST lines demonstrated HRD and synthetic cytotoxicity to c-RT with IR at 2Gy and Cisplatin 20uM of 7.50, and the lowest LST line with IR of 0.65. Of 4 evaluable patients on the Phase 2 trial, one achieved pathologic complete response (pCR) with corresponding HRD based on multiple genomic scar scores including HRDetect and LST scores, compared with patients without pCR. CONCLUSIONS: HRD breast cancers, whether identified by BRCA1/2 mutation status, functional tests or mutational signatures, appear to be significantly more sensitive to c-RT compared to isogenic controls or tumors without HRD mutational signature. HRD tumors may be exquisitely sensitive to c-RT and warrants further clinical investigation to guide a precision oncology approach.

Endometrial compaction to predict pregnancy outcomes in patients undergoing assisted reproductive technologies: a systematic review and meta-analysis.

STUDY QUESTION: Does endometrial compaction (EC) help predict pregnancy outcomes in those undergoing ART? SUMMARY ANSWER: EC is associated with a significantly higher clinical pregnancy rate (CPR) and ongoing pregnancy rate (OPR), but this does not translate to live birth rate (LBR). WHAT IS KNOWN ALREADY: EC describes the progesterone-induced decrease in endometrial thickness, which may be observed following the end of the proliferative phase, prior to embryo transfer. EC is proposed as a non-invasive tool to help predict pregnancy outcome in those undergoing ART, however, published data is conflicting. STUDY DESIGN SIZE DURATION: A literature search was carried out by two independent authors using PubMed, Cochrane Library, MEDLINE, Embase, Science Direct, Scopus, and Web of Science from inception of databases to May 2023. All peer-reviewed studies reporting EC and pregnancy outcomes in patients undergoing IVF/ICSI treatment were included. PARTICIPANTS/MATERIALS SETTING METHODS: The primary outcome is LBR. Secondary outcomes included other pregnancy metrics (positive pregnancy test (PPT), CPR, OPR, miscarriage rate (MR)) and rate of EC. Comparative meta-analyses comparing EC and no EC were conducted for each outcome using a random-effects model if I 2 > 50%. The Mantel-Haenszel method was applied for pooling dichotomous data. Results are presented as odds ratios (OR) with 95% CI. MAIN RESULTS AND THE ROLE OF CHANCE: Out of 4030 screened articles, 21 cohort studies were included in the final analysis (n = 27 857). No significant difference was found between LBR in the EC versus the no EC group (OR 0.95; 95% CI 0.87-1.04). OPR was significantly higher within the EC group (OR 1.61; 95% CI 1.09-2.38), particularly when EC ≥ 15% compared to no EC (OR 3.52; 95% CI 2.36-5.23). CPR was inconsistently defined across the studies, affecting the findings. When defined as a viable intrauterine pregnancy <12 weeks, the EC group had significantly higher CPR than no EC (OR 1.83; 95% CI 1.15-2.92). No significant differences were found between EC and no EC for PPT (OR 1.54; 95% CI 0.97-2.45) or MR (OR 1.06; 95% CI 0.92-1.56). The pooled weighted incidence of EC across all studies was 32% (95% CI 26-38%). LIMITATIONS REASONS FOR CAUTION: Heterogeneity due to differences between reported pregnancy outcomes, definition of EC, method of ultrasound, and cycle protocol may account for the lack of translation between CPR/OPR and LBR findings; thus, all pooled data should be viewed with an element of caution. WIDER IMPLICATIONS OF THE FINDINGS: In this dataset, the significantly higher CPR/OPR with EC does not translate to LBR. Although stratification of women according to EC cannot currently be recommended in clinical practice, a large and well-designed clinical trial to rigorously assess EC as a non-invasive predictor of a successful pregnancy is warranted. We urge for consistent outcome reporting to be mandated for ART trials so that data can be pooled, compared, and concluded on. STUDY FUNDING/COMPETING INTERESTS: H.A. was supported by the Hewitt Fertility Centre. S.G.P. and J.W. were supported by the Liverpool University Hospital NHS Foundation Trust. D.K.H. was supported by a Wellbeing of Women project grant (RG2137) and MRC clinical research training fellowship (MR/V007238/1). N.T. was supported by the National Institute for Health and Care Research. D.K.H. had received honoraria for consultancy for Theramex and has received payment for presentations from Theramex and Gideon Richter. The remaining authors have no conflicts of interest to report. REGISTRATION NUMBER: PROSPERO CRD42022378464.

Spatially Fractionated Radiotherapy in the Era of Immunotherapy.

Spatially fractionated radiotherapy (SFRT) includes historical grid therapy approaches but more recently encompasses the controlled introduction of one or more cold dose regions using intensity modulation delivery techniques. The driving hypothesis behind SFRT is that it may allow for an increased immune response that is otherwise suppressed by radiation effects. With both two- and three-dimensional SFRT approaches, SFRT dose distributions typically include multiple dose cold spots or valleys. Despite its unconventional methods, reported clinical experience shows that SFRT can sometimes induce marked tumor regressions, even in patients with large hypoxic tumors. Preclinical models using extreme dose distributions (i.e., half-sparing) have been shown to nevertheless result in full tumor eradications, a more robust immune response, and systemic anti-tumor immunity. SFRT takes advantage of the complementary immunomodulatory features of low- and high-dose radiotherapy to integrate the delivery of both into a single target. Clinical trials using three-dimensional SFRT (i.e., lattice-like dose distributions) have reported both promising tumor and toxicity results, and ongoing clinical trials are investigating synergy between SFRT and immunotherapies.

Breast Cancer Presenting With Intravascular Tumor Emboli in Axillary Soft Tissue: Recurrence Risk and Radiation Therapy Outcomes.

Purpose: Intravascular tumor emboli in axillary soft tissue (ITE) is a rare pathologic finding in breast cancer and is associated with higher axillary nodal disease burden. The independent prognostic and predictive value of this entity is unknown, as is the role of radiation therapy for ITE. Methods and Materials: We analyzed a prospectively maintained database of breast cancer patients treated from 1992 to 2020. Patients with ITE were matched to those without (1:2) based on propensity scores to control for potential confounding factors. Locoregional (LRR) and distant recurrence (DR) were evaluated using competing risks methods accounting for death as a competing event. Overall survival (OS) and disease-free survival (DFS) were evaluated by Cox regression models. Among patients with ITE, we also evaluated whether RT improved outcomes. Results: Among 2377 total patients, 129 had ITE, of whom 126 were propensity score matched to 252 without ITE. Median follow-up from time of surgery was 5.5 years (IQR 2.3, 9.7). There were no statistically significant differences in the 5-year incidence of LRR between groups (5.4% [95% CI, 1.6%-13%] with ITE vs 10% [95% CI, 6.7%-15%] without, P = .53) or DR (24% [95% CI, 15% 35%] with ITE vs 21% [95% CI, 16%-27%] without, P = .51). Five-year OS and DFS did not differ between groups (P > .9 for both comparisons, patients with ITE vs without ITE). In analyzing the effect of RT among patients with ITE, receipt of RT was associated with significantly improved DFS (HR, 0.34, 95% CI, 0.12-0.93, P = .04). Conclusions: Patients with ITE do not exhibit significantly worse LRR, DR, DFS, or OS compared with a propensity-score-matched cohort without ITE. However, among patients with ITE, those who received RT demonstrated significantly improved DFS. Larger studies with longer follow-up are needed to evaluate the prognostic and predictive implications of ITE.

The Presence of Extensive Lymphovascular Invasion is Associated With Higher Risks of Local-Regional Recurrence Compared With Usual Lymphovascular Invasion in Curatively Treated Breast Cancer Patients.

PURPOSE: Several data sets have demonstrated a correlation between lymphovascular invasion (LVI) and locoregional recurrence (LRR). Whether the observation of "extensive LVI" is a further and incremental determinant of LRR risk is unknown. We describe clinical outcomes in women with invasive breast cancer stratified by (1) absence of LVI (neg), (2) LVI focal or suspicious (FS-LVI), (3) usual (nonextensive) LVI (LVI), and (4) extensive LVI (E-LVI). METHODS AND MATERIALS: Between December 2009 and August 2021, 8837 patients with early-stage breast cancer were treated with curative intent and were evaluable. Clinical-pathologic details were abstracted by retrospective review. The description of LVI was abstracted from pathology reports. Recurrence and survival outcomes were compared based on the extent of LVI. A matched propensity score analysis compared outcomes between patients with LVI versus E-LVI. RESULTS: Of the 8837 patients studied, 5584 were negative, 461 had FS-LVI, 2315 had LVI, and 477 had E-LVI. Patients with E-LVI had an adverse risk profile compared with the other groups. The 5- and 10-year LRR cumulative incidence estimates in patients with E-LVI were 9.6% (95% CI, 7.1-13) and 13% (95% CI, 10-17), respectively, which were significantly higher than those observed in the usual LVI group (6.8% [5.7-7.9] and 10% [8.8-12], respectively). A statistically significant difference in LRR was demonstrated in univariable (HR, 1.4; 95% CI, 1.03-1.89; P = .029) and multivariable regression analysis (HR, 1.62; 95% CI, 1.15-2.27; P = .005) compared with nonextensive LVI. In an alternative approach, we performed a 2:1 propensity score matching analysis comparing patients with LVI to those with E-LVI. The hazard ratio for LRR (HR, 1.47; CI 1.02-2.14; P = .041) was suggestive of a higher risk associated with E-LVI. CONCLUSIONS: Our work suggests that patients with E-LVI are at a higher risk for LRR than those with usual LVI. For patients who are borderline candidates for regional nodal irradiation or post-mastectomy radiation therapy, the finding of E-LVI might be decisive in favor of intensified treatment.

APOBEC3 mutagenesis drives therapy resistance in breast cancer.

Acquired genetic alterations commonly drive resistance to endocrine and targeted therapies in metastatic breast cancer 1-7 , however the underlying processes engendering these diverse alterations are largely uncharacterized. To identify the mutational processes operant in breast cancer and their impact on clinical outcomes, we utilized a well-annotated cohort of 3,880 patient samples with paired tumor-normal sequencing data. The mutational signatures associated with apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) enzymes were highly prevalent and enriched in post-treatment compared to treatment-naïve hormone receptor-positive (HR+) cancers. APOBEC3 mutational signatures were independently associated with shorter progression-free survival on antiestrogen plus CDK4/6 inhibitor combination therapy in patients with HR+ metastatic breast cancer. Whole genome sequencing (WGS) of breast cancer models and selected paired primary-metastatic samples demonstrated that active APOBEC3 mutagenesis promoted resistance to both endocrine and targeted therapies through characteristic alterations such as RB1 loss-of-function mutations. Evidence of APOBEC3 activity in pre-treatment samples illustrated a pervasive role for this mutational process in breast cancer evolution. The study reveals APOBEC3 mutagenesis to be a frequent mediator of therapy resistance in breast cancer and highlights its potential as a biomarker and target for overcoming resistance.

Surgical Treatment for Endometrial Cancer, Hysterectomy Performed via Minimally Invasive Routes Compared with Open Surgery: A Systematic Review and Network Meta-Analysis.

Background: Total hysterectomy with bilateral salpingo-oophorectomy via minimally invasive surgery (MIS) has emerged as the standard of care for early-stage endometrial cancer (EC). Prior systematic reviews and meta-analyses have focused on outcomes reported solely from randomised controlled trials (RCTs), overlooking valuable data from non-randomised studies. This inaugural systematic review and network meta-analysis comprehensively compares clinical and oncological outcomes between MIS and open surgery for early-stage EC, incorporating evidence from randomised and non-randomised studies. Methods: This study was prospectively registered on PROSPERO (CRD42020186959). All original research of any experimental design reporting clinical and oncological outcomes of surgical treatment for endometrial cancer was included. Study selection was restricted to English-language peer-reviewed journal articles published 1 January 1995-31 December 2021. A Bayesian network meta-analysis was conducted. Results: A total of 99 studies were included in the network meta-analysis, comprising 181,716 women and 14 outcomes. Compared with open surgery, laparoscopic and robotic-assisted surgery demonstrated reduced blood loss and length of hospital stay but increased operating time. Compared with laparoscopic surgery, robotic-assisted surgery was associated with a significant reduction in ileus (OR = 0.40, 95% CrI: 0.17-0.87) and total intra-operative complications (OR = 0.38, 95% CrI: 0.17-0.75) as well as a higher disease-free survival (OR = 2.45, 95% CrI: 1.04-6.34). Conclusions: For treating early endometrial cancer, minimal-access surgery via robotic-assisted or laparoscopic techniques appears safer and more efficacious than open surgery. Robotic-assisted surgery is associated with fewer complications and favourable oncological outcomes.

A Phase II Study Evaluating the Effect of Intensity Modulated Postmastectomy Radiation Therapy on Implant Failure Rates in Breast Cancer Patients With Immediate, 2-Stage Implant Reconstruction With an MRI Imaging Correlative Substudy.

PURPOSE: Postmastectomy radiation therapy is a mainstay in the adjuvant treatment of node-positive breast cancer, but it poses risks for women with breast reconstruction. Multibeam intensity-modulated radiation therapy improves dose conformality and homogeneity, potentially reducing complications in breast cancer patients with implant-based reconstruction. To investigate this hypothesis, we conducted a single-arm phase 2 clinical trial of breast cancer patients who underwent mastectomy/axillary dissection and prosthesis-based reconstruction. METHODS AND MATERIALS: The primary endpoint was the rate of implant failure (IF) within 24 months of permanent implant placement, which would be considered an improvement over historical controls if below 16%. IF was defined as removal leading to a flat chest wall or replacement with another reconstruction. Patients were analyzed in 2 cohorts. Cohort 1 (RT-PI) received radiation therapy to the permanent implant. Cohort 2 (RT-TE) received radiation therapy to the TE. IF rates, adverse events, and quality of life were analyzed. Follow-up/postradiation therapy assessments were compared with the baseline/preradiation therapy assessments at 3 to 10 weeks after exchange surgery. A subgroup underwent serial magnetic resonance imaging (MRI) sessions to explore the association between MRI-detected changes and capsular contracture, a known adverse effect of radiation therapy. RESULTS: Between June 2014 and March 2017, 119 women were enrolled. Cohort 1 included 45 patients, and cohort 2 had 74 patients. Among 100 evaluable participants, 25 experienced IF during the study period. IF occurred in 8/42 (19%) and 17/58 (29%) in cohorts 1 and 2, respectively. Among the IFs, the majority were due to capsular contracture (13), infection (7), exposure (3), and other reasons (2). Morphologic shape features observed in longitudinal MRI images were associated with the development of Baker grade 3 to 4 contractures. CONCLUSIONS: The rate of IF in reconstructed breast cancer patients treated with intensity-modulated radiation therapy was similar to, but not improved over, that observed with conventional, 3-dimensional-conformal methods. MRI features show promise for predicting capsular contracture but require validation in larger studies.

Comparative Evaluation of Proton Therapy and Volumetric Modulated Arc Therapy for Brachial Plexus Sparing in the Comprehensive Reirradiation of High-Risk Recurrent Breast Cancer.

Purpose: Recurrent or new primary breast cancer requiring comprehensive regional nodal irradiation after prior radiation therapy (RT) to the supraclavicular area and upper axilla is challenging due to cumulative brachial plexus (BP) dose tolerance. We assessed BP dose sparing achieved with pencil beam scanning proton therapy (PBS-PT) and photon volumetric modulated arc therapy (VMAT). Methods and Materials: In an institutional review board-approved planning study, all patients with ipsilateral recurrent breast cancer treated with PBS-PT re-RT (PBT1) with at least partial BP overlap from prior photon RT were identified. Comparative VMAT plans (XRT1) using matched BP dose constraints were developed. A second pair of proton (PBT2) and VMAT (XRT2) plans using standardized target volumes were created, applying uniform prescription dose of 50.4 per 1.8 Gy and a maximum BP constraint <25 Gy. Incidence of brachial plexopathy was also assessed. Results: Ten consecutive patients were identified. Median time between RT courses was 48 months (15-276). Median first, second, and cumulative RT doses were 50.4 Gy (range, 42.6-60.0), 50.4 Gy relative biologic effectiveness (RBE) (45.0-64.4), and 102.4 Gy (RBE) (95.0-120.0), respectively. Median follow-up was 15 months (5-33) and 18 months for living patients (11-33) Mean BP max was 37.5 Gy (RBE) for PBT1 and 36.9 Gy for XRT1. Target volume coverage of V85% (volume receiving 85% of prescription dose), V90%, and V95% were numerically lower for XRT1 versus PBT1. Similarly, axilla I-III and supraclavicular area coverage were significantly higher for PBT2 than XRT2 at dose levels of V55%, V65%, V75%, V85%, and V95%. Only axilla I V55% did not reach significance (P = .06) favoring PBS-PT. Two patients with high cumulative BPmax (95.2 Gy [RBE], 101.6 Gy [RBE]) developed brachial plexopathy symptoms with ulnar nerve distribution neuropathy without pain or weakness (1 of 2 had symptom resolution after 6 months without intervention). Conclusions: PBS-PT improved BP sparing and target volume coverage versus VMAT. For patients requiring comprehensive re-RT for high-risk, nonmetastatic breast cancer recurrence with BP overlap and reasonable expectation for prolonged life expectancy, PBT may be the preferred treatment modality.

Anthracyclines induce cardiotoxicity through a shared gene expression response signature.

TOP2 inhibitors (TOP2i) are effective drugs for breast cancer treatment. However, they can cause cardiotoxicity in some women. The most widely used TOP2i include anthracyclines (AC) Doxorubicin (DOX), Daunorubicin (DNR), Epirubicin (EPI), and the anthraquinone Mitoxantrone (MTX). It is unclear whether women would experience the same adverse effects from all drugs in this class, or if specific drugs would be preferable for certain individuals based on their cardiotoxicity risk profile. To investigate this, we studied the effects of treatment of DOX, DNR, EPI, MTX, and an unrelated monoclonal antibody Trastuzumab (TRZ) on iPSC-derived cardiomyocytes (iPSC-CMs) from six healthy females. All TOP2i induce cell death at concentrations observed in cancer patient serum, while TRZ does not. A sub-lethal dose of all TOP2i induces limited cellular stress but affects calcium handling, a function critical for cardiomyocyte contraction. TOP2i induce thousands of gene expression changes over time, giving rise to four distinct gene expression response signatures, denoted as TOP2i early-acute, early-sustained, and late response genes, and non-response genes. There is no drug- or AC-specific signature. TOP2i early response genes are enriched in chromatin regulators, which mediate AC sensitivity across breast cancer patients. However, there is increased transcriptional variability between individuals following AC treatments. To investigate potential genetic effects on response variability, we first identified a reported set of expression quantitative trait loci (eQTLs) uncovered following DOX treatment in iPSC-CMs. Indeed, DOX response eQTLs are enriched in genes that respond to all TOP2i. Next, we identified 38 genes in loci associated with AC toxicity by GWAS or TWAS. Two thirds of the genes that respond to at least one TOP2i, respond to all ACs with the same direction of effect. Our data demonstrate that TOP2i induce thousands of shared gene expression changes in cardiomyocytes, including genes near SNPs associated with inter-individual variation in response to DOX treatment and AC-induced cardiotoxicity.

Hypoxia-Directed Treatment of Human Papillomavirus-Related Oropharyngeal Carcinoma.

PURPOSE: Standard curative-intent chemoradiotherapy for human papillomavirus (HPV)-related oropharyngeal carcinoma results in significant toxicity. Since hypoxic tumors are radioresistant, we posited that the aerobic state of a tumor could identify patients eligible for de-escalation of chemoradiotherapy while maintaining treatment efficacy. METHODS: We enrolled patients with HPV-related oropharyngeal carcinoma to receive de-escalated definitive chemoradiotherapy in a phase II study (ClinicalTrials.gov identifier: NCT03323463). Patients first underwent surgical removal of disease at their primary site, but not of gross disease in the neck. A baseline 18F-fluoromisonidazole positron emission tomography scan was used to measure tumor hypoxia and was repeated 1-2 weeks intratreatment. Patients with nonhypoxic tumors received 30 Gy (3 weeks) with chemotherapy, whereas those with hypoxic tumors received standard chemoradiotherapy to 70 Gy (7 weeks). The primary objective was achieving a 2-year locoregional control (LRC) of 95% with a 7% noninferiority margin. RESULTS: One hundred fifty-eight patients with T0-2/N1-N2c were enrolled, of which 152 patients were eligible for analyses. Of these, 128 patients met criteria for 30 Gy and 24 patients received 70 Gy. The 2-year LRC was 94.7% (95% CI, 89.8 to 97.7), meeting our primary objective. With a median follow-up time of 38.3 (range, 22.1-58.4) months, the 2-year progression-free survival (PFS) and overall survival (OS) rates were 94% and 100%, respectively, for the 30-Gy cohort. The 70-Gy cohort had similar 2-year PFS and OS rates at 96% and 96%, respectively. Acute grade 3-4 adverse events were more common in 70 Gy versus 30 Gy (58.3% v 32%; P = .02). Late grade 3-4 adverse events only occurred in the 70-Gy cohort, in which 4.5% complained of late dysphagia. CONCLUSION: Tumor hypoxia is a promising approach to direct dosing of curative-intent chemoradiotherapy for HPV-related carcinomas with preserved efficacy and substantially reduced toxicity that requires further investigation.

Omission of Radiotherapy After Breast-Conserving Surgery for Women With Breast Cancer With Low Clinical and Genomic Risk: 5-Year Outcomes of IDEA.

PURPOSE: Multiple studies have shown a low risk of ipsilateral breast events (IBEs) or other recurrences for selected patients age 65-70 years or older with stage I breast cancers treated with breast-conserving surgery (BCS) and endocrine therapy (ET) without adjuvant radiotherapy. We sought to evaluate whether younger postmenopausal patients could also be successfully treated without radiation therapy, adding a genomic assay to classic selection factors. METHODS: Postmenopausal patients age 50-69 years with pT1N0 unifocal invasive breast cancer with margins ≥2 mm after BCS whose tumors were estrogen receptor-positive, progesterone receptor-positive, and human epidermal growth factor receptor 2-negative with Oncotype DX 21-gene recurrence score ≤18 were prospectively enrolled in a single-arm trial of radiotherapy omission if they consented to take at least 5 years of ET. The primary end point was the rate of locoregional recurrence 5 years after BCS. RESULTS: Between June 2015 and October 2018, 200 eligible patients were enrolled. Among the 186 patients with clinical follow-up of at least 56 months, overall and breast cancer-specific survival rates at 5 years were both 100%. The 5-year freedom from any recurrence was 99% (95% CI, 96 to 100). Crude rates of IBEs for the entire follow-up period for patients age 50-59 years and age 60-69 years were 3.3% (2/60) and 3.6% (5/140), respectively; crude rates of overall recurrence were 5.0% (3/60) and 3.6% (5/140), respectively. CONCLUSION: This trial achieved a very low risk of recurrence using a genomic assay in combination with classic clinical and biologic features for treatment selection, including postmenopausal patients younger than 60 years. Long-term follow-up of this trial and others will help determine whether the option of avoiding initial radiotherapy can be offered to a broader group of women than current guidelines recommend.

Accelerated Partial Breast Irradiation for HER2-Positive Early-Stage Breast Cancer.

PURPOSE: HER2-positive (HER2+) breast cancer historically exhibited the most adverse local outcomes and, consequently, has had limited representation among trials of partial breast irradiation (PBI). We hypothesized that with contemporary HER2-targeted agents, patients may now exhibit excellent disease control outcomes after adjuvant PBI. METHODS AND MATERIALS: Using a prospectively maintained institutional database, we identified patients with HER2+ breast cancer treated with breast conserving surgery (BCS) and PBI from 2000 to 2022. Salient clinicopathologic and treatment parameters were collected. All patients received external beam PBI to 40 Gy in 10 daily fractions. Cumulative incidence functions were calculated to estimate the incidence of local recurrence (LR) with the competing risk of death. RESULTS: We identified 1248 patients who underwent PBI at our institution, of whom the study cohort comprised 52 (4%) with HER2+ breast cancer (median age, 64 years; range, 44-87). Nearly all had T1 tumors (98%; median size, 12 mm [range, 1-21 mm]). Most had estrogen receptor positive disease (88%), and all patients had negative surgical margins. Nearly all underwent sentinel node biopsy (94%), with the remainder undergoing no surgical axillary evaluation. Forty-two (81%) received chemotherapy; 40 (77%), hormone therapy; and 42 (81%), HER2-directed therapy, most commonly trastuzumab. At 143.8 person-years of follow-up (range, 7-226 months for each patient), we observed 2 LR events at 14 and 26 months, respectively, yielding a 2-year LR rate of 3.8%. No regional or distant recurrences were observed, nor were any breast-specific mortality events. Two deaths were observed, both without evidence of disease. CONCLUSIONS: Among a cohort of patients with HER2+ early-stage breast cancer managed with BCS and PBI, we observed a 2-year LR rate of 3.8%, with no regional or distant recurrences and excellent overall survival. These findings require confirmation with longer follow-up among larger cohorts but appear consistent with the excellent results of contemporary randomized trials of PBI unselected for HER2 status.

Prophylactic Radiation Therapy Versus Standard of Care for Patients With High-Risk Asymptomatic Bone Metastases: A Multicenter, Randomized Phase II Clinical Trial.

PURPOSE: External-beam radiation therapy (RT) is standard of care (SOC) for pain relief of symptomatic bone metastases. We aimed to evaluate the efficacy of radiation to asymptomatic bone metastases in preventing skeletal-related events (SRE). METHODS: In a multicenter randomized controlled trial, adult patients with widely metastatic solid tumor malignancies were stratified by histology and planned SOC (systemic therapy or observation) and randomly assigned in a 1:1 ratio to receive RT to asymptomatic high-risk bone metastases or SOC alone. The primary outcome of the trial was SRE. Secondary outcomes included hospitalizations for SRE and overall survival (OS). RESULTS: A total of 78 patients with 122 high-risk bone metastases were enrolled between May 8, 2018, and August 9, 2021, at three institutions across an affiliated cancer network in the United States. Seventy-three patients were evaluable for the primary end point. The most common primary cancer types were lung (27%), breast (24%), and prostate (22%). At 1 year, SRE occurred in one of 62 bone metastases (1.6%) in the RT arm and 14 of 49 bone metastases (29%) in the SOC arm (P < .001). There were significantly fewer patients hospitalized for SRE in the RT arm compared with the SOC arm (0 v 4, P = .045). At a median follow-up of 2.5 years, OS was significantly longer in the RT arm (hazard ratio [HR], 0.49; 95% CI, 0.27 to 0.89; P = .018), which persisted on multivariable Cox regression analysis (HR, 0.46; 95% CI, 0.23 to 0.85; P = .01). CONCLUSION: Radiation delivered prophylactically to asymptomatic, high-risk bone metastases reduced SRE and hospitalizations. We also observed an improvement in OS with prophylactic radiation, although a confirmatory phase III trial is warranted.

Standard-of-care systemic therapy with or without stereotactic body radiotherapy in patients with oligoprogressive breast cancer or non-small-cell lung cancer (Consolidative Use of Radiotherapy to Block [CURB] oligoprogression): an open-label, randomised, controlled, phase 2 study.

BACKGROUND: Most patients with metastatic cancer eventually develop resistance to systemic therapy, with some having limited disease progression (ie, oligoprogression). We aimed to assess whether stereotactic body radiotherapy (SBRT) targeting oligoprogressive sites could improve patient outcomes. METHODS: We did a phase 2, open-label, randomised controlled trial of SBRT in patients with oligoprogressive metastatic breast cancer or non-small-cell lung cancer (NSCLC) after having received at least first-line systemic therapy, with oligoprogression defined as five or less progressive lesions on PET-CT or CT. Patients aged 18 years or older were enrolled from a tertiary cancer centre in New York, NY, USA, and six affiliated regional centres in the states of New York and New Jersey, with a 1:1 randomisation between standard of care (standard-of-care group) and SBRT plus standard of care (SBRT group). Randomisation was done with a computer-based algorithm with stratification by number of progressive sites of metastasis, receptor or driver genetic alteration status, primary site, and type of systemic therapy previously received. Patients and investigators were not masked to treatment allocation. The primary endpoint was progression-free survival, measured up to 12 months. We did a prespecified subgroup analysis of the primary endpoint by disease site. All analyses were done in the intention-to-treat population. The study is registered with ClinicalTrials.gov, NCT03808662, and is complete. FINDINGS: From Jan 1, 2019, to July 31, 2021, 106 patients were randomly assigned to standard of care (n=51; 23 patients with breast cancer and 28 patients with NSCLC) or SBRT plus standard of care (n=55; 24 patients with breast cancer and 31 patients with NSCLC). 16 (34%) of 47 patients with breast cancer had triple-negative disease, and 51 (86%) of 59 patients with NSCLC had no actionable driver mutation. The study was closed to accrual before reaching the targeted sample size, after the primary efficacy endpoint was met during a preplanned interim analysis. The median follow-up was 11·6 months for patients in the standard-of-care group and 12·1 months for patients in the SBRT group. The median progression-free survival was 3·2 months (95% CI 2·0-4·5) for patients in the standard-of-care group versus 7·2 months (4·5-10·0) for patients in the SBRT group (hazard ratio [HR] 0·53, 95% CI 0·35-0·81; p=0·0035). The median progression-free survival was higher for patients with NSCLC in the SBRT group than for those with NSCLC in the standard-of-care group (10·0 months [7·2-not reached] vs 2·2 months [95% CI 2·0-4·5]; HR 0·41, 95% CI 0·22-0·75; p=0·0039), but no difference was found for patients with breast cancer (4·4 months [2·5-8·7] vs 4·2 months [1·8-5·5]; 0·78, 0·43-1·43; p=0·43). Grade 2 or worse adverse events occurred in 21 (41%) patients in the standard-of-care group and 34 (62%) patients in the SBRT group. Nine (16%) patients in the SBRT group had grade 2 or worse toxicities related to SBRT, including gastrointestinal reflux disease, pain exacerbation, radiation pneumonitis, brachial plexopathy, and low blood counts. INTERPRETATION: The trial showed that progression-free survival was increased in the SBRT plus standard-of-care group compared with standard of care only. Oligoprogression in patients with metastatic NSCLC could be effectively treated with SBRT plus standard of care, leading to more than a four-times increase in progression-free survival compared with standard of care only. By contrast, no benefit was observed in patients with oligoprogressive breast cancer. Further studies to validate these findings and understand the differential benefits are warranted. FUNDING: National Cancer Institute.

A Potential Pitfall and Clinical Solutions in Surface-Guided Deep Inspiration Breath Hold Radiation Therapy for Left-Sided Breast Cancer.

Purpose: Deep inspiration breath hold (DIBH) is an effective technique to spare the heart in treating left-sided breast cancer. Surface-guided radiation therapy (SGRT) is increasingly applied in DIBH setup and motion monitoring. Patient-specific breathing behavior, either thoracically driven or abdominally driven (A-DIBH), should be unaltered, online identified, and monitored accordingly to ensure reproducible heart-sparing treatment. Methods and Materials: Sixty patients with left-sided breast cancer treated with SGRT were analyzed: 20 A-DIBH patients with vertical chest elevation (VCE ≤ 5 mm) were prospectively identified, and 40 control patients were retrospectively and randomly selected for comparison. At simulation, both free-breathing (FB) and DIBH computed tomography (CT) were acquired, guided by a motion surrogate placed around the xiphoid process. For SGRT treatment setups, the region of interest (ROI) was defined on the CT chest surface, and the surrogate-based setup was a backup. For all 60 patients, the VCE was measured as the average of the FB-to-DIBH elevations at the breast and xiphoid process, together with abdominal elevation. In the 40-patient control group, A-DIBH patients (VCE ≤ 5 mm) were identified. Of the 20 A-DIBH patients, 10 were treated with volumetric modulated arc therapy plans, and 10 patients were treated with tangent plans. Clinical DIBH plans were recalculated on FB CT to compare maximum dose (DMax), 5% of the maximum dose (D5%), mean dose (DMean), and V30Gy, V20Gy, and V5Gy of the heart and lungs and their significance. Results: In the 20 A-DIBH patients, VCE = 3 ± 2 mm, surrogate motion (9 ± 6 mm), and abdomen motion of 14 ± 5 mm are found. Heart dose reduction from FB to DIBH is significant (P < .01): ∆DMax = -8.4 ± 9.8 Gy, ∆D5% = -2.4 ± 4.4 Gy, and ∆DMean = -0.6 ± 0.9 Gy. Six out of 40 control patients (15%) are found to have VCE ≤ 5 mm. Conclusions: A-DIBH (VCE ≤ 5 mm) patient population is significant (15%), and they should be identified in the SGRT workflow and monitored accordingly. A new abdominal ROI or an abdominal surrogate should be used instead of the conventional chest-only ROI. Patient-specific DIBH should be preserved for higher reproducibility to ensure heart sparing.

Proton Reirradiation for High-Risk Recurrent or New Primary Breast Cancer.

Radiotherapy is an integral component of multidisciplinary breast cancer care. Given how commonly radiotherapy is used in the treatment of breast cancer, many patients with recurrences have received previous radiotherapy. Patients with new primary breast cancer may also have received previous radiotherapy to the thoracic region. Curative doses and comprehensive field photon reirradiation (reRT) have often been avoided in these patients due to concerns for severe toxicities to organs-at-risk (OARs), such as the heart, lungs, brachial plexus, and soft tissue. However, many patients may benefit from definitive-intent reRT, such as patients with high-risk disease features such as lymph node involvement and dermal/epidermal invasion. Proton therapy is a potentially advantageous treatment option for delivery of reRT due to its lack of exit dose and greater conformality that allow for enhanced non-target tissue sparing of previously irradiated tissues. In this review, we discuss the clinical applications of proton therapy for patients with breast cancer requiring reRT, the currently available literature and how it compares to historical photon reRT outcomes, treatment planning considerations, and questions in this area warranting further study. Given the dosimetric advantages of protons and the data reported to date, proton therapy is a promising option for patients who would benefit from the added locoregional disease control provided by reRT for recurrent or new primary breast cancer.

Most large structural variants in cancer genomes can be detected without long reads.

Short-read sequencing is the workhorse of cancer genomics yet is thought to miss many structural variants (SVs), particularly large chromosomal alterations. To characterize missing SVs in short-read whole genomes, we analyzed 'loose ends'-local violations of mass balance between adjacent DNA segments. In the landscape of loose ends across 1,330 high-purity cancer whole genomes, most large (>10-kb) clonal SVs were fully resolved by short reads in the 87% of the human genome where copy number could be reliably measured. Some loose ends represent neotelomeres, which we propose as a hallmark of the alternative lengthening of telomeres phenotype. These pan-cancer findings were confirmed by long-molecule profiles of 38 breast cancer and melanoma cases. Our results indicate that aberrant homologous recombination is unlikely to drive the majority of large cancer SVs. Furthermore, analysis of mass balance in short-read whole genome data provides a surprisingly complete picture of cancer chromosomal structure.

What is the optimal timing of surgery after short-course radiotherapy for rectal cancer?

BACKGROUND: Short-course neoadjuvant radiotherapy is a valuable tool in managing rectal cancers and has improved local recurrence rates. However, limited and conflicting data has resulted in variable usage and a lack of consensus on the optimal timing of surgery following short-course radiotherapy. This review aims to provide a contemporary summation of the available evidence regarding the optimal time interval between short-course neoadjuvant radiotherapy and surgery. METHODS: A focused literature search was undertaken using the PubMed and Embase databases from January 1980 until January 2023. Randomised control trials, large observational studies and systematic reviews focusing on the use of short-course preoperative radiotherapy for localised rectal cancers, with a focus on the timing of surgery, were included. Primary outcomes were overall survival, disease-free survival and perioperative complications. RESULTS: Five randomised control trials, two meta-analyses, and two large, population-based studies were included for their eligibility and relevance. Increased downstaging and fewer postoperative complications are demonstrated in patients receiving delayed surgery (> four weeks), but more recent data raise concerns regarding increased rates of local recurrence in this cohort. Studies directly comparing different time intervals to surgery following short-course radiotherapy have failed to demonstrate an effect on overall survival. CONCLUSIONS: This review highlights the complexities and relative shortcomings of the available data with few high-quality studies and randomised control trials directly comparing different time intervals to surgery following short-course radiotherapy. Continuing research is needed to confirm existing findings and explore gaps in the current literature.