Early breast cancer in women aged 35 years or younger: A large national multicenter French population-based case control-matched analysis.

BACKGROUND: There is a scarcity of data exploring early breast cancer (eBC) in very young patients. We assessed shared and intrinsic prognostic factors in a large cohort of patients aged ≤35, compared to a control group aged 36 to 50.

METHODS: Patients ≤50 were retrospectively identified from a multicentric cohort of 23,134 eBC patients who underwent primary surgery between 1990 and 2014. Multivariate Cox analyses for DFS and OS were built. To assess the independent impact of age, 1 to 3 case-control analysis was performed by matching ≤35 and 36-50 years patients.

RESULTS: Of 6481 patients, 556 were aged ≤35, and 5925 from 36 to 50. Age ≤35 was associated with larger tumors, higher grade, ER-negativity, macroscopic lymph node involvement (pN + macro), lymphovascular invasion (LVI), mastectomy, and chemotherapy (CT) use. In multivariate analysis, age ≤35 was associated with worse DFS [HR 1.56, 95% CI 1.32-1.84; p < 0.001], and OS [HR 1.29, 95% CI 1.03-1.60; p = 0.025], as were high grade, large tumor, LVI, pN + macro, ER-negativity, period of diagnostic, and absence of ET or CT (for DFS). Adverse prognostic impact of age ≤35 was maintained in the case control-matched analysis for DFS [HR 1.56, 95%CI 1.28-1.91, p < 0.001], and OS [HR 1.33, 95%CI 1.02-1.73, p = 0.032]. When only considering patients ≤35, ER, tumor size, nodal status, and LVI were independently associated with survival in this subgroup.

CONCLUSIONS: Age ≤35 is associated with less favorable presentation and more aggressive treatment strategies. Our results support the poor prognosis value of young age, which independently persisted when adjusting for other prognostic factors and treatments.