Better 10-Year Survival Reported With Breast-Conserving Surgery and Radiotherapy vs Mastectomy in Early Breast Cancer
In a Dutch population-based study reported in The Lancet Oncology, van Maaren et al found that breast-conserving surgery plus radiotherapy was associated with improved 10-year survival vs mastectomy in women with early breast cancer.
Study Details
The study included data from 37,207 women from the Netherlands Cancer Registry diagnosed with primary invasive stage T1–2, N0–1, M0 breast cancer between January 2000 and December 2004 who received either breast-conserving surgery plus radiotherapy (n = 21,734; 58%) or mastectomy (n = 15,473; 42%) irrespective of axillary staging or dissection or use of adjuvant systemic therapy. To adjust for confounders, multivariate analyses included factors that significantly differed between treatment groups in univariate analysis.
Improved Survival
Median follow-up was 11.4 years. Breast-conserving surgery plus radiotherapy was associated with improved 10-year overall survival in unadjusted analysis (hazard ratio [HR] = 0.51, P < .0001). In multivariate analysis adjusted for age, socioeconomic status, hospital volume, region, sublocalization of tumor, histologic tumor type, differentiation grade, tumor size, number of positive lymph nodes, hormone receptor status, and adjuvant systemic therapy, the benefit of breast-conserving surgery plus radiotherapy remained significant (adjusted HR = 0.81, P < .0001), with significant improvements being found in all T and N stages.
In a 2003 representative subcohort, including 7,552 patients with characteristics similar to those in the entire cohort, 4,647 (62%) received breast-conserving surgery plus radiotherapy, and 2,905 (38%) received mastectomy. In adjusted analysis, breast-conserving surgery plus radiotherapy did not significantly improve 10-year distant metastasis–free survival (adjusted HR = 0.88, P = .07) among all patients but did so in the subgroup with T1N0 disease (adjusted HR = 0.74, P = .014). Ten-year relative survival (compared with the general population) in the 2003 cohort was improved with breast-conserving surgery plus radiotherapy vs mastectomy overall (adjusted HR = 0.76, P = .003) and in the T1N0 subgroup (adjusted HR = 0.60, P = .004).
The investigators concluded: “Adjusting for confounding variables, breast-conserving surgery plus radiotherapy showed improved 10 year overall and relative survival compared with mastectomy in early breast cancer, but 10 year distant metastasis-free survival was improved with breast-conserving surgery plus radiotherapy compared with mastectomy in the T1N0 subgroup only, indicating a possible role of confounding by severity. These results suggest that breast-conserving surgery plus radiotherapy is at least equivalent to mastectomy with respect to overall survival and may influence treatment decision making for patients with early breast cancer.”
Sabine Siesling, PhD, of the Netherlands Comprehensive Cancer Organisation, Utrecht, is the corresponding author of The Lancet Oncology article.
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