Breast-conserving Surgery and Radiotherapy May Provide Better Overall Survival Than Mastectomy

Breast-conserving surgery plus radiotherapy appears to be at least equivalent to mastectomy for overall survival in patients with early breast cancer, a study published in the journal The Lancet Oncology has shown.¹

Previously reported registry-based studies suggest improved survival with breast-conserving surgery plus radiotherapy compared with mastectomy for patients with early breast cancer. Researchers compared the 10-year overall and breast cancer-specific survival after breast-conserving surgery plus radiotherapy with mastectomy in Dutch women with early breast cancer.

Investigators analyzed data from 37,207 women with primary, invasive, stage T1-2, N0-1, M0 breast cancer diagnosed between 2000 and 2004 that were included in the Netherlands Cancer Registry. Patients had undergone breast-conserving surgery plus radiotherapy or mastectomy, regardless of axillary staging, dissection, or use of adjuvant systemic therapy.

Adjusting for confounding factors, breast-conserving surgery plus radiotherapy was significantly associated with improved 10-year overall survival in the whole cohort, compared with mastectomy (hazard ratio, 0.81; 95% CI, 0.78-0.85; P < .0001). Subgroup analyses of different T and N stages of breast cancer demonstrated continued significance in improved 10-year survival.

Of a representative subcohort of 7552 patients whose characteristics were similar to the entire cohort, 62% received the combination approach and 38% underwent mastectomy. In this subcohort, breast-conserving surgery plus radiotherapy did not significantly improve 10-year distant metastasis-free survival versus mastectomy (hazard ratio, 0.88; 95% CI, 0.77-1.01; P = .07); the subgroup of patients with T1N0 disease, however, had significantly improved 10-year distant metastasis-free survival with the combination approach (hazard ratio, 0.74; 95% CI, 0.58-0.94; P = .014).

The study further demonstrated that breast-conserving surgery plus radiation treatment was significantly associated with improved 10-year relative survival in the subcohort (hazard ratio, 0.76; 95% CI, 0.64-0.91; P = .003) and in the T1N0 subgroup (hazard ratio, 0.60; 95% CI, 0.42-0.85; P = .004), compared with mastectomy.  

Reference

1. van Maaren MC, de Munck L, de Bock GH, Jobsen JJ, van Dalen T, Linn SC, et al. 10 year survival after breast-conserving surgery plus radiotherapy compared with mastectomy in early breast cancer in the Netherlands: a population-based study [published online ahead of print June 22, 2016]. Lancet Oncol. doi: 10.1016/S1470-2045(16)30067-5.