e11036 Background: It remains controversial if young age at diagnosis is an independent prognostic factor for recurrence in breast cancer (BC) patients. Data regarding recurrence with long-term follow-up in premenopausal women are sparse. The aim of the study was to compare the outcome of young patients (<=39 years) with older premenopausal patients. Methods: We collected clinical and pathological data from an inception cohort of 241 premenopausal patients aged <=50 years at diagnosis with stage I-III BC between January 2000 and December 2005 in a single institution. Disease-free survival (DFS) event was defined as time from diagnosis to local or distant recurrence, contralateral invasive BC or death from any cause. Kaplan-Meier curves and Cox model were used to analyze the covariable predictors for recurrence. Results: Median age was 43 years (range: 24-50) and median follow-up was 100 months (range: 72-137). Seventy seven patients (32%) were <=39 and 164 (68%) >39 years of age at diagnosis. Five and 10-year disease-free survival rate was 61 % and 48% respectively for the younger group and 77% and 74% for the older group (p<0.001). In the univariate analysis the hazard ratio (HR) for recurrence in young patients was 2.16 (95%CI: 1.38-3.37) (p< 0.001) Adjusting for T stage (<=2 cm versus >2 cm), N (negative versus positive nodes), Grade (grade 1-2 versus grade 3) and Hormonal Receptor status (positive versus negative), age less than 40 remains and independent prognostic factor for recurrence with an adjusted HR of 2.42 (95%CI: 1.42-4.10) (p<0.001), and was the most important adverse independent predictor among the factors included in the model. Conclusions: BC patients younger than 40 years of age at diagnosis have worse prognosis than older premenopausal patients, and have an independent prognostic value for recurrence after adjusting for known prognostic factors.