Oncologic outcomes of de-escalating axillary treatment in clinically node-positive breast cancer patients treated with neoadjuvant systemic therapy - A two center cohort study.

BACKGROUND: The aim of the present study was to report the 5-year axillary recurrence-free interval (aRFI) in clinically node-positive breast cancer patients treated according to a de-escalating axillary treatment protocol after neoadjuvant systemic therapy (NST). METHODS: All patients diagnosed in two hospitals between October 2014 and March 2021 were identified retrospectively. Data on diagnostic workup, treatment and follow-up was collected. Adjuvant axillary treatment was considered based on the initial staging using 18F-FDG PET/CT and the results of axillary lymph node marking with a radioactive-iodine seed protocol or a targeted axillary dissection procedure. Follow-up was updated until 27th April 2024. Kaplan-Meier curves were calculated to report the 5-year aRFI with corresponding 95 % confident intervals (95%-CI). RESULTS: A total of 199 patients were included. Axillary pathological complete response was reported in 66 (33.2 %). Based on the treatment protocol and initial clinical staging, no adjuvant axillary treatment was indicated in 30 patients (15 %), while 139 (70 %) received axillary radiotherapy without performance of an axillary lymph node dissection (ALND). The remaining 30 patients (15 %) underwent an ALND with additional locoregional radiotherapy. A median follow-up of 62 months (30-106) showed that 4 (2 %) patients experienced an axillary recurrence after 7, 8, 36 and 36 months, respectively. In all 4 patients, synchronous distant metastases were diagnosed. The estimated 5-year aRFI was 97.8 % (95%-CI 95.6-99.9 %) CONCLUSION: Although longer follow-up should be awaited before final conclusions can be drawn regarding the oncological safety of this approach, the implementation of a de-escalating axillary treatment protocol appears to be safe since the estimated 5-year aRFI is 97.8 %.

The prognostic impact of BMI in patients with HR+/HER2- advanced breast cancer: a study of the SONABRE registry.

PURPOSE: This study determines the prognostic impact of body mass index (BMI) in patients with hormone receptor-positive/human epidermal growth factor receptor-2-negative (HR+/HER2-) advanced (i.e., metastatic) breast cancer (ABC). METHODS: All patients with HR+/HER2- ABC who received endocrine therapy +-a cyclin-dependent kinase 4/6 inhibitor as first-given systemic therapy in 2007-2020 in the Netherlands were identified from the Southeast Netherlands Advanced Breast Cancer (SONABRE) registry (NCT03577197). Patients were categorised as underweight (BMI: < 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), or obese (≥ 30.0 kg/m2). Overall survival (OS) and progression-free survival (PFS) were compared between BMI classes using multivariable Cox regression analyses. RESULTS: This study included 1456 patients, of whom 35 (2%) were underweight, 580 (40%) normal weight, 479 (33%) overweight, and 362 (25%) obese. No differences in OS were observed between normal weight patients and respectively overweight (HR 0.99; 95% CI 0.85-1.16; p = 0.93) and obese patients (HR 1.04; 95% CI 0.88-1.24; p = 0.62). However, the OS of underweight patients (HR 1.45; 95% CI 0.97-2.15; p = 0.07) tended to be worse than the OS of normal weight patients. When compared with normal weight patients, the PFS was similar in underweight (HR 1.05; 95% CI 0.73-1.51; p = 0.81), overweight (HR 0.90; 95% CI 0.79-1.03; p = 0.14), and obese patients (HR 0.88; 95% CI 0.76-1.02; p = 0.10). CONCLUSION: In this study among 1456 patients with HR+/HER2- ABC, overweight and obesity were prevalent, whereas underweight was uncommon. When compared with normal weight, overweight and obesity were not associated with either OS or PFS. However, underweight seemed to be an adverse prognostic factor for OS.

Trastuzumab Resistance in Patients With HER2-Positive Advanced Breast Cancer: Results From the SONABRE Registry.

BACKGROUND: This study aims to explore whether first-line pertuzumab use modifies the effect of prior use of (neo-) adjuvant trastuzumab on the PFS of first-line HER2-targeted therapy in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (ABC). METHODS: Patients diagnosed with HER2-positive ABC in 2008 to 2018 in 9 Dutch hospitals were derived from the SONABRE Registry (NCT03577197). Patients diagnosed with de novo metastatic breast cancer were excluded. Patients receiving first-line trastuzumab-based therapy for ABC were selected and divided into trastuzumab naïve (n = 113) and trastuzumab pretreated (n = 112). Progression-free survival (PFS) was compared using multivariable Cox proportional hazard models. The interaction effect of first-line pertuzumab was tested using the likelihood-ratio test. RESULTS: The median follow-up time was 47 months (95% confidence interval [CI]: 42-52). When comparing trastuzumab pretreated with trastuzumab naïve patients, the hazard ratio for first-line progression was 2.07 (CI:1.47-2.92). For trastuzumab pretreated patients who received first-line trastuzumab without pertuzumab, the hazard ratio for progression was 2.60 (95% CI:1.72-3.93), whereas for those who received first-line trastuzumab with pertuzumab the hazard ratio was 1.43 (95% CI: 0.81-2.52) (P interaction = .10). CONCLUSIONS: Prior use of trastuzumab as (neo-)adjuvant treatment had a negative impact on PFS of first-line HER2-targeted therapy outcomes. Adding pertuzumab to first-line trastuzumab-based therapy decreased the negative impact of prior (neo-)adjuvant trastuzumab use on first-line PFS. Further studies are needed to assess the effect of prior (neo-)adjuvant pertuzumab use on the outcomes of first-line pertuzumab-based therapy.

Real-world time trends in overall survival, treatments and patient characteristics in HR+/HER2- metastatic breast cancer: an observational study of the SONABRE Registry.

Background: This study aims to evaluate whether changes in therapeutic strategies have improved survival of patients diagnosed with hormone receptor positive (HR+), HER2 negative (HER2-) advanced breast cancer (ABC) in real-world. Methods: All 1950 patients systemically treated for HR+/HER2- ABC and diagnosed between 2008 and 2019 in eight hospitals were retrieved from the SONABRE Registry (NCT-03577197). Patients were categorized per three-year cohorts based on year of ABC diagnosis. Tests for trend were used to examine differences in baseline characteristics, Kaplan-Meier methods and Cox proportional hazards for survival analyses, and competing-risk methods for 3-year use of systemic therapy. Findings: Over time, patients were older (≥70 years, 37%, n = 169/456 in 2008-2010, 47%, n = 233/493 in 2017-2019, p = 0.004) and more often had multiple metastatic sites at ABC diagnosis (48%, n = 220/456 in 2008-2010, 56%, n = 275/493 in 2017-2019, p = 0.002). Among patients with metachronous metastases the prior exposure to (neo-) adjuvant therapies increased over time (chemotherapy, 38%, n = 138/362 in 2008-2010, 48%, n = 181/376 in 2017-2019, p = <0.001; endocrine therapy, 64%, n = 231/362 in 2008-2010, 72%, n = 271/376 in 2017-2019, p = <0.001). Overall survival significantly improved from median 31.1 months (95% CI:28.2-34.3) for patients diagnosed in 2008-2010 to 38.4 months (95% CI:34.0-41.1) in 2017-2019 (adjusted hazard ratio = 0.76, 95% CI:0.64-0.90; p = 0.001). Three-year use of CDK4/6 inhibitors increased from 0% for patients diagnosed in 2008-2010 to 54% for diagnosis in 2017-2019. Conversely, three-year use of chemotherapy was 50% versus 36%, respectively. Interpretation: Over time, patients diagnosed with HR+/HER2- ABC presented with less favourable patient characteristics. Nevertheless, we observed that overall survival of ABC increased between 2008 and 2019, with increased use of endocrine/targeted therapies. Funding: The SONABRE Registry is supported by the Netherlands Organization for Health Research and Development (ZonMw: 80-82500-98-8003); Novartis BV; Roche; Pfizer; and Eli Lilly & Co. Funding sources had no role in the writing of the manuscript.

The initial hormone receptor/HER2 subtype is the main determinator of subtype discordance in advanced breast cancer: a study of the SONABRE registry.

PURPOSE: The hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) are the main parameters in guiding systemic treatment choices in breast cancer, but can change during the disease course. This study aims to evaluate the biopsy rate and receptor subtype discordance rate in patients diagnosed with advanced breast cancer (ABC). METHODS: Patients diagnosed with ABC in seven hospitals in 2007-2018 were selected from the SOutheast Netherlands Advanced BREast cancer (SONABRE) registry. Multivariable logistic regression analyses were performed to identify factors influencing biopsy and discordance rates. RESULTS: Overall, 60% of 2854 patients had a biopsy of a metastatic site at diagnosis. One of the factors associated with a reduced biopsy rate was the HR + /HER2 + primary tumor subtype (versus HR + /HER2- subtype: OR = 0.68; 95% CI: 0.51-0.90). Among the 748 patients with a biopsy of the primary tumor and a metastatic site, the overall receptor discordance rate was 18%. This was the highest for the HR + /HER2 + primary tumor subtype, with 55%. In 624 patients with metachronous metastases, the HR + /HER2 + subtype remained the only predictor significantly related to a higher discordance rate, irrespective of prior (neo-)adjuvant therapies (OR = 7.49; 95% CI: 3.69-15.20). CONCLUSION: The HR + /HER2 + subtype has the highest discordance rate, but the lowest biopsy rate of all four receptor subtypes. Prior systemic therapy was not independently related to subtype discordance. This study highlights the importance of obtaining a biopsy of metastatic disease, especially in the HR + /HER2 + subtype to determine the most optimal treatment strategy.

The implementation of CDK 4/6 inhibitors and its impact on treatment choices in HR+/HER2- advanced breast cancer patients: A study of the Dutch SONABRE Registry.

In August 2017, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors combined with endocrine therapy have been reimbursed in the Netherlands for patients with hormone receptor positive (HR+), HER2 negative (HER2-) advanced breast cancer (ABC). This study evaluates the implementation of CDK4/6 inhibitors and changes in treatment choices in the Netherlands. All patients diagnosed with HR+/HER2- ABC in 2009 to 2018 in seven hospitals were selected from the Southeast Netherlands Advanced Breast cancer (SONABRE) registry. The 2-year cumulative use of CDK4/6 inhibitors since reimbursement date (August 2017) was assessed using competing-risk methodology in two cohorts. The first cohort included patients with ABC diagnosis between August 2017 and December 2018. The second cohort included patients with ABC diagnosis between 2009 and August 2017, and still alive on August 1, 2017. In addition, treatment choices in the first three lines of therapy in calendar years 2009 to 2018 were evaluated for the total study population. Among patients diagnosed since August 2017 (n = 214), 50% (95% confidence interval [CI] = 43-57) received CDK4/6 inhibitors within 2 years beyond diagnosis. Of eligible patients diagnosed before August 2017 (n = 417), 31% (95% CI = 27-36) received CDK4/6 inhibitors within 2 years following reimbursement. Another 20% of both cohorts are still CDK4/6 inhibitor naïve and on first-line therapy. The use of chemotherapy decreased in first two lines of therapy between 2009 and 2018 (first-line: 29%-13%; second-line: 26%-19%). The implementation rate of CDK4/6 inhibitors since reimbursement is currently 50% within 2 years beyond diagnosis and is expected to increase further. The implementation of targeted therapy decreased the use of chemotherapy as first-line therapy.