Prognosis and adjuvant treatment effects in very young women (below 35 years) with operable breast cancer

Background: There is limited knowledge about prognosis of selected breast cancer subtypes among very young women Patients and Methods: We explored patterns of recurrence by age according to four immunohistochemically-defined tumor subtypes: triple negative, HER2 positive (and) endocrine receptor absent, Luminal A and Luminal B (ER-positive and/or PR-positive and either HER2-positive and/or high Ki67) in 2970 premenopausal patients with pT1-3, pN0-3 and M0 breast cancer. Results: Patients below 35 years of age (315, 11%) presented a significantly increased risk of recurrence and death (HR=1.65, 95%CI 1.30-2.10 and HR=1.78, 95%CI 1.12-2.85, respectively) when compared with older patients (2655, 89%) with similar characteristics of disease. This was true considering patients with luminal B (HR 1.62, 95%CI, 1.21-2.18, for DFS; HR 2.09, 95%CI, 0.96-4.53, for OS) and with triple-negative (HR 2.04, 95%CI, 1.11-3.72, for DFS; HR 2.20, 95%CI, 1.10-4.41, for OS) breast cancer, observing the highest risk of recurrence in the younger patients with HER2 positive breast cancer (HR 2.37, 95% CI, 1.12-5.02), when compared with older patients. Conclusions: Very young patients with triple negative, luminal B, or HER2 positive breast cancer have a worse prognosis when compared with older patients with similar characteristics of disease.