A large registry study found that certain breast cancer patients gain a significant survival benefit with breast conserving surgery plus radiation therapy compared with mastectomy.
A large registry study found that certain breast cancer patients gain a significant survival benefit with breast conserving surgery plus radiation therapy (BCT) compared with mastectomy. This includes patients over the age of 50 with T1–2N0–1 disease, and other factors.
Studies comparing those options have often excluded elderly patients, or those with existing comorbidities. The new study involved two time cohorts from a Netherlands registry, one with 55,802 patients diagnosed between 1999 and 2005, and another with 65,394 patients diagnosed between 2006 and 2012. The results were presented by Mirelle Lagendijk, MD, of the Erasmus MC Cancer Institute in Rotterdam, at the European Cancer Congress 2017 in Amsterdam.
In the full cohorts, BCT was correlated with better breast cancer-specific survival (BCSS); in the 1999–2005 group, the hazard ratio (HR) for BCSS with BCT vs mastectomy was 0.72 (95% CI, 0.69–0.76), which was significant across all T1–2N0–2 stages. In the later cohort, the HR for BCSS was 0.75 (95% CI, 0.70–0.80), which was significant for T1–2N0–1 disease but not in T1–2N2 stages, where the two were equivalent.
Similarly, overall survival was better with BCT. In the earlier cohort, the HR for overall survival was 0.74 (95% CI, 0.71–0.76); in the later group, it was 0.67 (95% CI, 0.64–0.71).
Subgroup analyses revealed specifically which patients seem to derive most benefit from BCT vs mastectomy. In both time cohorts, patients who were older than 50 fared better with BCT; for those above age 75, the HR for BCSS in the 1999–2005 patients was 0.69 (95% CI, 0.60–0.78) and in the 2006–2012 cohort was 0.66 (95% CI, 0.55–0.79).
Patients who received no systemic therapy also received more benefit from BCT. In the earlier cohort, those patients had an HR for BCSS of 0.75 (95% CI, 0.70–0.80); in the later cohort, the HR was 0.66 (95% CI, 0.57–0.75). In the later cohort, patients with comorbidity did better with BCT, with an HR of 0.60 (95% CI, 0.48–0.76), while those without comorbidities did not, with an HR of 0.84 (95% CI, 0.67–1.05).
“Although this study is based on retrospective data with much detailed data, and residual confounding factors cannot be ruled out completely, we believe that this information will have potential to greatly improve shared treatment decision-making for future breast cancer patients in those aged over 50 years and those with comorbidity,” said the study’s senior author, Sabine Siesling, PhD, of the University of Twente, in Enschede, Netherlands, in a press release.
She noted that this does not necessarily make mastectomy a bad option. “For patients for whom radiotherapy is not suitable or feasible due to social circumstances, for whom the risk of late side effects of radiotherapy is high, or who have the prospect of a poor aesthetic outcome following BCT, a mastectomy may still be the preferable treatment option,” she said.