Clinical Biomarkers of Tumour Radiosensitivity and Predicting Benefit from Radiotherapy: A Systematic Review.

Modern advanced radiotherapy techniques have improved the precision and accuracy of radiotherapy delivery, with resulting plans being highly personalised based on individual anatomy. Adaptation for individual tumour biology remains elusive. There is an unmet need for biomarkers of intrinsic radiosensitivity that can predict tumour response to radiation to facilitate individualised decision-making, dosing and treatment planning. Over the last few decades, the use of high throughput molecular biology technologies has led to an explosion of newly discovered cancer biomarkers. Gene expression signatures are now used routinely in clinic to aid decision-making regarding adjuvant systemic therapy. They have great potential as radiotherapy biomarkers. A previous systematic review published in 2015 reported only five studies of signatures evaluated for their ability to predict radiotherapy benefits in clinical cohorts. This updated systematic review encompasses the expanded number of studies reported in the last decade. An additional 27 studies were identified. In total, 22 distinct signatures were recognised (5 pre-2015, 17 post-2015). Seventeen signatures were 'radiosensitivity' signatures and five were breast cancer prognostic signatures aiming to identify patients at an increased risk of local recurrence and therefore were more likely to benefit from adjuvant radiation. Most signatures (15/22) had not progressed beyond the discovery phase of development, with no suitable validated clinical-grade assay for application. Very few signatures (4/17 'radiosensitivity' signatures) had undergone any laboratory-based biological validation of their ability to predict tumour radiosensitivity. No signatures have been assessed prospectively in a phase III biomarker-led trial to date and none are recommended for routine use in clinical guidelines. A phase III prospective evaluation is ongoing for two breast cancer prognostic signatures. The most promising radiosensitivity signature remains the radiosensitivity index (RSI), which is used to calculate a genomic adjusted radiation dose (GARD). There is an ongoing phase II prospective biomarker-led study of RSI/GARD in triple negative breast cancer. The results of these trials are eagerly anticipated over the coming years. Future work in this area should focus on (1) robust biological validation; (2) building biobanks alongside large radiotherapy randomised controlled trials with dose variance (to demonstrate an interaction between radiosensitivity signature and dose); (3) a validation of clinical-grade cost-effective assays that are deliverable within current healthcare infrastructure; and (4) an integration with biomarkers of other determinants of radiation response.

Post-mastectomy radiotherapy for women with early breast cancer and one to three positive lymph nodes.

BACKGROUND: Continual improvement in adjuvant therapies has resulted in a better prognosis for women diagnosed with breast cancer. A surrogate marker used to detect the spread of disease after treatment of breast cancer is local and regional recurrence. The risk of local and regional recurrence after mastectomy increases with the number of axillary lymph nodes affected by cancer. There is a consensus to use radiotherapy as an adjuvant treatment after mastectomy (postmastectomy radiotherapy (PMRT)) in women diagnosed with breast cancer and found to have disease in four or more positive axillary lymph nodes. Despite data showing almost double the risk of local and regional recurrence in women treated with mastectomy and found to have one to three positive lymph nodes, there is a lack of international consensus on the use of PMRT in this group. OBJECTIVES: To assess the effects of PMRT in women diagnosed with early breast cancer and found to have one to three positive axillary lymph nodes. SEARCH METHODS: We searched the Cochrane Breast Cancer Group's Specialised Register, CENTRAL, MEDLINE, Embase, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov up to 24 September 2021. SELECTION CRITERIA: We included randomised controlled trials (RCTs). The inclusion criteria included women diagnosed with breast cancer treated with simple or modified radical mastectomy and axillary surgery (sentinel lymph node biopsy (SLNB) alone or those undergoing axillary lymph node clearance with or without prior SLNB). We included only women receiving PMRT using X-rays (electron and photon radiation), and we defined the radiotherapy dose to reflect what is currently being recommended (i.e. 40 Gray (Gy) to 50 Gy in 15 to 25/28 fractions in 3 to 5 weeks. The included studies did not administer any boost to the tumour bed. In this review, we excluded studies using neoadjuvant chemotherapy as a supportive treatment before surgery. DATA COLLECTION AND ANALYSIS: We used Covidence to screen records. We collected data on tumour characteristics, adjuvant treatments and the outcomes of local and regional recurrence, overall survival, disease-free survival, time to progression, short- and long-term adverse events and quality of life. We reported on time-to-event outcome measures using the hazard ratio (HR) and subdistribution HR. We used Cochrane's risk of bias tool (RoB 1), and we presented overall certainty of the evidence using the GRADE approach. MAIN RESULTS: The RCTs included in this review were subgroup analyses of original RCTs conducted in the 1980s to assess the effectiveness of PMRT. Hence, the type and duration of adjuvant systemic treatments used in the studies included in this review were suboptimal compared to the current standard of care. The review involved three RCTs with a total of 829 women diagnosed with breast cancer and low-volume axillary disease. Amongst the included studies, only a single study pertained to the modern-day radiotherapy practice. The results from this one study showed a reduction of local and regional recurrence (HR 0.20, 95% confidence interval (CI) 0.13 to 0.33, 1 study, 522 women; low-certainty evidence) and improvement in overall survival with PMRT (HR 0.76, 95% CI 0.60 to 0.97, 1 study, 522 women; moderate-certainty evidence). One of the other studies using radiotherapy techniques that do not reflect modern-day practice reported on disease-free survival in women with low-volume axillary disease (subdistribution HR 0.63, 95% CI 0.41 to 0.96, 1 study, 173 women). None of the included studies reported on PMRT side effects or quality-of-life outcome measures. AUTHORS' CONCLUSIONS: Based on one study, the use of PMRT in women diagnosed with breast cancer and low-volume axillary disease indicated a reduction in locoregional recurrence and an improvement in survival. There is a need for more research to be conducted using modern-day radiotherapy equipment and methods to support and supplement the review findings.

Estimating the percentage of patients who might benefit from proton beam therapy instead of X-ray radiotherapy.

OBJECTIVES: High-energy Proton Beam Therapy (PBT) commenced in England in 2018 and NHS England commissions PBT for 1.5% of patients receiving radical radiotherapy. We sought expert opinion on the level of provision. METHODS: Invitations were sent to 41 colleagues working in PBT, most at one UK centre, to contribute by completing a spreadsheet. 39 responded: 23 (59%) completed the spreadsheet; 16 (41%) declined, arguing that clinical outcome data are lacking, but joined six additional site-specialist oncologists for two consensus meetings. The spreadsheet was pre-populated with incidence data from Cancer Research UK and radiotherapy use data from the National Cancer Registration and Analysis Service. 'Mechanisms of Benefit' of reduced growth impairment, reduced toxicity, dose escalation and reduced second cancer risk were examined. RESULTS: The most reliable figure for percentage of radical radiotherapy patients likely to benefit from PBT was that agreed by 95% of the 23 respondents at 4.3%, slightly larger than current provision. The median was 15% (range 4-92%) and consensus median 13%. The biggest estimated potential benefit was from reducing toxicity, median benefit to 15% (range 4-92%), followed by dose escalation median 3% (range 0 to 47%); consensus values were 12 and 3%. Reduced growth impairment and reduced second cancer risk were calculated to benefit 0.5% and 0.1%. CONCLUSIONS: The most secure estimate of percentage benefit was 4.3% but insufficient clinical outcome data exist for confident estimates. The study supports the NHS approach of using the evidence base and developing it through randomised trials, non-randomised studies and outcomes tracking. ADVANCES IN KNOWLEDGE: Less is known about the percentage of patients who may benefit from PBT than is generally acknowledged. Expert opinion varies widely. Insufficient clinical outcome data exist to provide robust estimates. Considerable further work is needed to address this, including international collaboration; much is already underway but will take time to provide mature data.

Selection criteria for early breast cancer patients in the DBCG proton trial - The randomised phase III trial strategy.

BACKGROUND AND PURPOSE: Adjuvant radiotherapy of internal mammary nodes (IMN) improves survival in high-risk early breast cancer patients but inevitably leads to more dose to heart and lung. Target coverage is often compromised to meet heart/lung dose constraints. We estimate heart and lung dose when target coverage is not compromised in consecutive patients. These estimates are used to guide the choice of selection criteria for the randomised Danish Breast Cancer Group (DBCG) Proton Trial. MATERIALS AND METHODS: 179 breast cancer patients already treated with loco-regional IMN radiotherapy from 18 European departments were included. If the clinically delivered treatment plan did not comply with defined target coverage requirements, the plan was modified retrospectively until sufficient coverage was reached. The choice of selection criteria was based on the estimated number of eligible patients for different heart and lung dose thresholds in combination with proton therapy capacity limitations and dose-response relationships for heart and lung. RESULTS: Median mean heart dose was 3.0 Gy (range, 1.1-8.2 Gy) for left-sided and 1.4 Gy (0.4-11.5 Gy) for right-sided treatment plans. Median V17Gy/V20Gy (hypofractionated/normofractionated plans) for ipsilateral lung was 31% (9-57%). The DBCG Radiotherapy Committee chose mean heart dose ≥ 4 Gy and/or lung V17Gy/V20Gy ≥ 37% as thresholds for inclusion in the randomised trial. Using these thresholds, we estimate that 22% of patients requiring loco-regional IMN radiotherapy will be eligible for the trial. CONCLUSION: The patient selection criteria for the DBCG Proton Trial are mean heart dose ≥ 4 Gy and/or lung V17Gy/V20Gy ≥ 37%.

Optimizing MR-Guided Radiotherapy for Breast Cancer Patients.

Current research in radiotherapy (RT) for breast cancer is evaluating neoadjuvant as opposed to adjuvant partial breast irradiation (PBI) with the aim of reducing the volume of breast tissue irradiated and therefore the risk of late treatment-related toxicity. The development of magnetic resonance (MR)-guided RT, including dedicated MR-guided RT systems [hybrid machines combining an MR scanner with a linear accelerator (MR-linac) or 60Co sources], could potentially reduce the irradiated volume even further by improving tumour visibility before and during each RT treatment. In this position paper, we discuss MR guidance in relation to each step of the breast RT planning and treatment pathway, focusing on the application of MR-guided RT to neoadjuvant PBI.

Consensus on Contouring Primary Breast Tumors on MRI in the Setting of Neoadjuvant Partial Breast Irradiation in Trials.

PURPOSE: Our purpose was to present and evaluate expert consensus on contouring primary breast tumors on magnetic resonance imaging (MRI) in the setting of neoadjuvant partial breast irradiation in trials. METHODS AND MATERIALS: Expert consensus on contouring guidelines for target definition of primary breast tumors on contrast-enhanced MRI in trials was developed by an international team of experienced breast radiation oncologists and a dedicated breast radiologist during 3 meetings. At the first meeting, draft guidelines were developed through discussing and contouring 2 cases. At the second meeting 6 breast radiation oncologists delineated gross tumor volume (GTV) in 10 patients with early-stage breast cancer (cT1N0) according to draft guidelines. GTV was expanded isotropically (20 mm) to generate clinical target volume (CTV), excluding skin and chest wall. Delineations were reviewed for disagreement and guidelines were clarified accordingly. At the third meeting 5 radiation oncologists redelineated 6 cases using consensus-based guidelines. Interobserver variation of GTV and CTV was assessed using generalized conformity index (CI). CI was calculated as the sum of volumes each pair of observers agreed upon, divided by the sum of encompassing volumes for each pair of observers. RESULTS: For the 2 delineation sessions combined, mean GTV ranged between 0.19 and 2.44 cm3, CI for GTV ranged between 0.28 and 0.77, and CI for CTV between 0.77 and 0.94. The largest interobserver variation in GTV delineations was observed in cases with extended tumor spiculae, blood vessels near or markers within the tumor, or with increased enhancement of glandular breast tissue. Consensus-based guidelines stated to delineate all visible tumors on contrast enhanced-MRI scan 1 to 2 minutes after contrast injection and if a marker was inserted in the tumor to include this. CONCLUSIONS: Expert-based consensus on contouring primary breast tumors on MRI in trials has been reached. This resulted in low interobserver variation for CTV in the context of a uniform 20 mm GTV to CTV expansion margin.

Tolerability of Concurrent Chemoradiation Therapy With Gemcitabine (GemX), With and Without Prior Neoadjuvant Chemotherapy, in Muscle Invasive Bladder Cancer.

PURPOSE: The aim of this study is to assess the tolerability of concurrent chemoradiation therapy with gemcitabine (GemX) in muscle invasive bladder cancer following neoadjuvant chemotherapy (neoGemX) by use of patient- and provider-reported outcomes. METHODS AND MATERIALS: Seventy-eight patients were treated with GemX. Thirty-eight received prior neoadjuvant chemotherapy (NAC). Patients were prospectively assessed during treatment and at 6 weeks and 12 months after treatment completion. Radiation therapy was given to a total dose of 52.5 Gy in 20 fractions with weekly concurrent gemcitabine chemotherapy, 100 mg/m2. Toxicity was assessed by the care provider and by a patient-reported outcome questionnaire collecting scores on the late effects in normal tissues-subjective, objective, management, and analytic scales and was statistically compared at baseline and 12 months, as well as between the neoGemX and GemX groups. RESULTS: The median duration of follow-up was 15.9 months. The radiation therapy completion rate was 95%, and 96% of patients completed at least 3 cycles of gemcitabine. Bowel toxicity of grade 3 or greater was reported in 7 of 38 patients (18%) in the neoGemX group and 5 of 25 (20%) in the GemX group. Three GemX and two neoGemX patients had grade 3 or greater urinary toxicity. Forty-nine patients completed questionnaires and were included in the analysis. Scores on the late effects in normal tissues-subjective, objective, management, and analytic scales showed an expected peak by week 4 of treatment. There was no statistically significant difference between mean scores at baseline and 12 months after treatment completion or between the neoGemX and GemX groups. CONCLUSIONS: This study demonstrates that GemX, alone or following NAC, has manageable toxicity and acceptable treatment completion rates. Allowing for small patient numbers and the nonrandomized nature of this study, these results do not suggest any additional toxicity from the use of NAC prior to GemX.

The case for including bowel urgency in toxicity reporting after pelvic cancer treatment.

Bowel toxicity is a major complication of cancer treatment, and its accurate reporting is important for assessing outcomes. The NCI's Common Terminology Criteria for Adverse Events (CTCAE) is the preferred method for capturing adverse events after all cancer treatments, particularly within clinical trials. However, the CTCAE version 4 does not include urgency of defecation as an item, despite this being one of the most common and persistent adverse consequences of treatment of pelvic cancers. The importance of bowel urgency to patients is well documented, and this treatment effect has a negative impact on social function and quality of life. Bowel urgency is also important clinically because it may represent significant underlying problems. This article presents the case for including patient reported assessment of bowel urgency as an independent item in cancer treatment adverse event reporting.

Early prostate cancer--which treatment do men prefer and why?

STUDY TYPE: Preference (prospective cohort). LEVEL OF EVIDENCE: 1b. What's known on the subject? and What does the study add? In general the literature suggests that there is a need for improvement in aiding men diagnosed with early prostate cancer in their decision making about treatment options and that our understanding of this process is inadequate. There is limited data analyzing the reasons why these men decide between potentially curative or observational treatments and data evaluating patients' views before and after definitive therapy are scarce. This study begins the process of understanding the reasons underlying a patient's final treatment decision. Being a prospective study, it looks at the thought processes of these men before treatment during the time the decision is made. It also documents how satisfied patients are with their choice after their treatment and whether they would choose the same treatment again. OBJECTIVE: To identify the reasons for patients with localised prostate cancer choosing between treatments and the relationship of procedure type to patient satisfaction post-treatment. PATIENTS AND METHODS: 768 men with prostate cancer (stage T1/2, Gleason≤7, PSA<20 ug/L) chose between four treatments: radical prostatectomy, brachytherapy, conformal radiotherapy and active surveillance. Prior to choosing, patients were counselled by a urological surgeon, clinical (radiation) oncologist and uro-oncology specialist nurse. Pre-treatment reasons for choice were recorded. Post-treatment satisfaction was examined via postal questionnaire. RESULTS: Of the 768 patients, 305 (40%) chose surgery, 237 (31%) conformal beam radiotherapy, 165 (21%) brachytherapy and 61 (8%) active surveillance. Sixty percent of men who opted for radical prostatectomy were motivated by the need for physical removal of the cancer. Conformal radiotherapy was mainly chosen by patients who feared other treatments (n=63, 27%). Most men chose brachytherapy because it was more convenient for their lifestyle (n=64, 39%). Active surveillance was chosen by patients for more varied reasons. Post-treatment satisfaction was assessed in a subgroup who took part in the QOL aspect of this study. Of the respondents to the questionnaire, 212(87.6%) stated that they were satisfied/extremely satisfied with their choice and 171(92.9%) indicated they would choose the same treatment again. CONCLUSION: Men with early prostate cancer have clear reasons for making decisions about treatment. Overall, patients were satisfied with the treatment and indicated that despite different reasons for choosing treatment, they would make the same choice again.

Development of a patient-reported questionnaire for collecting toxicity data following prostate brachytherapy.

PURPOSE: To improve a questionnaire used to collect patient-reported outcomes from patients with early stage prostate cancer treated with brachytherapy. A secondary aim was to adapt the Late Effects of Normal Tissue (LENT) subjective toxicity questionnaire for use to collect Common Terminology Criteria for Adverse Events (CTCAE) data, the current preferred platform for assessing radiation toxicity. MATERIALS AND METHODS: Three hundred and seventy-seven patients were treated with permanent iodine-125 seed implant brachytherapy for early prostate cancer. Toxicity data were collected before and at nine time points post-treatment (0-36 months). Compliance rates for patients completing individual items and item-subsection correlation coefficients were calculated. A factor analysis was carried out to analyse responses to the questionnaire and identify less informative questions, which could be removed. Cronbach's α coefficient was used to measure reliability. RESULTS: Two thousand one hundred and eighty-eight questionnaires were analysed. There was poor compliance for questions specifically relating to operations and bowel medication. We found that the division of the questionnaire into subsections based on anatomical site was reasonable and that certain items could be safely removed. The high mean value for Cronbach's α across all questionnaires (0.752; 95% CI: 0.726-0.779) indicated that the questionnaire was reliable. Fifteen of the 44 questions were removed from the original questionnaires. Questions on urinary incontinence severity, management of urinary and bowel incontinence, effects of reduced flow of urine and the effects of symptoms on activity of daily living and change in sexual function were required to adapt the LENT subjective questionnaire for use to collect CTCAE data. CONCLUSIONS: A questionnaire, validated over 6 years to collect LENT subjective data were adapted and is a reliable approach for collecting CTCAE data after prostate brachytherapy.