Radiation therapy to the primary tumor for de novo metastatic breast cancer and overall survival in a retrospective multicenter cohort analysis.

BACKGROUND: The impact of locoregional treatment (LRT) on overall survival (OS) in de novo metastatic breast cancer (dnMBC) is still under debate, with very few data available regarding exclusive radiotherapy (ERT) as a therapeutic modality. METHODS: We evaluated the impact of ERT, exclusive surgery, or a combination of surgery plus radiotherapy (bimodality therapy, BMT) on survival outcomes in a national real-life dnMBC cohort. The primary and secondary end points were OS and progression free survival (PFS) according to LRT (ERT, exclusive surgery, BMT) and no LRT. Sensitivity analyses were performed using propensity score matched analyses. RESULTS: From 2008 to 2014, 4507 dnMBC patients were identified. Only patients alive and free from progression under systemic therapy at least 1 year after diagnosis were included (n = 1965). Forty-five percent of patients (891/1965) underwent LRT: 41.1% (n = 366) ERT, 13.7% (n = 122) exclusive surgery, and 45.2% (n = 403) BMT. OS adjusted for major prognostic factors was significantly longer in the ERT and BMT group compared with no-LRT group, but not exclusive surgery (hazard ratio (HR) = 0.63, 95% confidence interval (CI) [0.49, 0.80], p < 0.001, HR = 0.61, 95%CI [0.47, 0.78], p < 0.001 and HR = 0.87, 95%CI [0.61, 1.26], p = 0.466 respectively). Results were similar after matching on a propensity score. ERT, surgery and BMT were all associated with a significantly better PFS in multivariable analysis. CONCLUSION: ERT was significantly associated with better OS in dnMBC, in the same magnitude as BMT, compared with no-LRT. However, even with statistical models adjusted for known prognostic factors and propensity score analysis, selection biases cannot be eliminated from observational studies.

Survival Impact of Locoregional Treatment of the Primary Tumor in De Novo Metastatic Breast Cancers in a Large Multicentric Cohort Study: A Propensity Score-Matched Analysis.

INTRODUCTION: Improvement in overall survival (OS) by locoregional treatment (LRT) of the primary tumor in de novo metastatic breast cancer (MBC) patients remains controversial. OBJECTIVE: The aim of our study was to evaluate the impact of LRT on OS in a large retrospective cohort of de novo MBC patients, with regard to immunohistochemical characteristics and pattern of metastatic dissemination. METHODS: We conducted a multicentric retrospective study of patients diagnosed with de novo MBC selected from the French Epidemiological Strategy and Medical Economics MBC database (NCT03275311) between 2008 and 2014. Overall, 4276 women were included in the study. LRT comprised either radiotherapy, surgery, or both. RESULTS: LRT was used in 40% of patients. Compared with no LRT, patients who received LRT were younger (p < 0.0001) and were more likely to have only one metastatic site (p < 0.0001) or bone-only metastases (p < 0.0001). LRT was associated with a significantly better OS based on landmark multivariate analysis at 1-year (hazard ratio 0.65, 95% confidence interval 0.55-0.76, p < 0.001). Similar results were observed in all sensitivity analyses, including propensity score matching. In subgroup analysis, LRT was associated with better OS in patients with hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative (61.6 vs. 45.9 months, p < 0.001) and HER2-positive tumors (77.2 vs. 52.6 months, p = 0.008), but not in triple-negative tumors (19 vs. 18.6 months, p = 0.54), and was also associated with a reduction in the risk of death in visceral metastatic patients (p < 0.001). CONCLUSIONS: LRT was associated with a significantly better OS in de novo MBC patients, including patients with visceral involvement at diagnosis; however, LRT did not impact OS in triple-negative MBC.

Medico-economic impact of MSKCC non-sentinel node prediction nomogram for ER-positive HER2-negative breast cancers.

BACKGROUND: Avoiding axillary lymph node dissection (ALND) for invasive breast cancers with isolated tumor cells or micrometastatic sentinel node biopsy (SNB) could decrease morbidity with minimal clinical significance. PURPOSE: The aim of this study is to simulate the medico-economic impact of the routine use of the MSKCC non-sentinel node (NSN) prediction nomogram for ER+ HER2- breast cancer patients. METHODS: We studied 1036 ER+ HER2- breast cancer patients with a metastatic SNB. All had a complementary ALND. For each patient, we calculated the probability of the NSN positivity using the MSKCC nomogram. After validation of this nomogram in the population, we described how the patients' characteristics spread as the threshold value changed. Then, we performed an economic simulation study to estimate the total cost of caring for patients treated according to the MSKCC predictive nomogram results. RESULTS: A 0.3 threshold discriminate the type of sentinel node (SN) metastases: 98.8% of patients with pN0(i+) and 91.6% of patients with pN1(mic) had a MSKCC score under 0.3 (false negative rate = 6.4%). If we use the 0.3 threshold for economic simulation, 43% of ALND could be avoided, reducing the costs of caring by 1 051 980 EUROS among the 1036 patients. CONCLUSION: We demonstrated the cost-effectiveness of using the MSKCC NSN prediction nomogram by avoiding ALND for the pN0(i+) or pN1(mic) ER+ HER2- breast cancer patients with a MSKCC score of less than or equal to 0.3.