1002
Background: Young age has been identified as an independent predictor of recurrence and mortality in women with breast cancer. The equivalence of breast conserving surgery (BCS) with mastectomy remains unclear in this population in an era of multimodal therapy. We sought to determine the effect of surgery type on the risk of recurrence and survival in a large, population based cohort of very young women. Methods: All women diagnosed with breast cancer aged ≤35 between 1994 and 2003 in Ontario were identified from the Ontario Cancer Registry, a population based registry of all incident invasive breast cancers in the province. A retrospective chart review was undertaken to identify patient, tumor and treatment variables, as well as locoregional, distant recurrences and death. Univariable and multivariable Cox proportional hazards regression models were fit to determine the effect of primary surgery type on overall survival while controlling for known confounders. To examine time to recurrence in a multivariable analysis, the proportional subdistribution hazards model (Fine and Gray) was used to account for death being a competing risk. Results: A total of 1,381 patients were identified; the median age was 33 (range 18 – 35), median follow up was 11 years. Primary surgical treatment was BCS in 793 (57%) patients of which 89% had adjuvant radiotherapy. Of the 588 (43%) having mastectomy, 53% underwent post mastectomy radiation. Overall, 38% of patients sustained a recurrence of any type and 31% had died. After controlling for tumor size, margin status, node status, grade, LVI, ER/PR, HER2 and treatment (chemotherapy, radiation, hormones) there was no difference in overall survival (HR 0.99, 95% CI 0.79,1.26) or recurrence (HR 0.96, 95% CI 0.73,1.26) among women treated with BCS or mastectomy. Predictors of recurrence were size ≥2 cm, ≥ 1 positive node, neoadjuvant chemotherapy, and lack of radiation. Predictors of death were similar and included high grade and presence of LVI. Conclusions: Very young women selected for BCS had similar outcomes to those selected for mastectomy after controlling for known prognostic factors for recurrence and death.