Are breast conservation and mastectomy equally effective in the treatment of young women with early breast cancer? Long-term results of a population-based cohort of 1,451 patients aged ≤40 years

To compare the effectiveness of breast-conserving therapy (BCT) and mastectomy, all women aged ≤40 years, treated for early-stage breast cancer in the southern part of the Netherlands between 1988 and 2005, were identified. A total of 562 patients underwent mastectomy and 889 patients received BCT. During follow-up, 23 patients treated with mastectomy and 135 patients treated with BCT developed a local relapse without previous or simultaneous evidence of distant disease. The local relapse risk for patients treated with mastectomy was 4.4% (95% confidence interval (CI) 2.4–6.4) at 5 years and reached a plateau after 6 years at 6.0% (95% CI 3.5–8.5). After BCT, the 5-, 10- and 15-year risks were 8.3% (95% CI 6.3–10.5), 18.4% (95% CI 15.0–21.8) and 28.2% (95% CI 23.0–33.4), respectively ( P