Purpose: Whether young age at diagnosis of breast cancer is an independent risk factor for death remains controversial, and the question whether young age should be considered in treatment decisions is still to be answered.
Methods: From a population-based cohort of 22,017 women with breast cancer, all women <35 years (n = 471) were compared to a random sample of 700 women aged 35-69 years from the same cohort. Information on patient and tumor characteristics, treatment, and follow-up was collected from the medical records. Tissue microarrays were produced for analysis of classical biomarkers. Breast cancer-specific survival (BCSS), distant disease-free survival (DDFS), and locoregional recurrence-free survival (LRFS) by age were compared using women 50-69 years as reference.
Results: At 10 years follow-up, women <35 years and 35-39 years had a worse BCSS [age <35 years 69 % (HR 2.75, 95 % CI 1.93-3.94), age 35-39 years 76 % (HR 2.33, 95 % CI 1.54-3.52), age 40-49 years 84 % (HR 1.53, 95 % CI 0.97-2.39), and age 50-69 years 89 % (reference)]. The worse BCSS was statistically significant in stages I-IIa and Luminal B tumors. At multivariate analysis age <35 years and 35-39 years confined a risk in LRFS (HR 2.13, 95 % CI 1.21-3.76 and HR 1.97, 95 % CI 1.06-3.68) but not in DDFS and BCSS. In the subgroup of women <40 years with luminal tumors stage I-IIa, low age remained an independent risk factor also in DDFS (HR 1.87, 95 % CI 1.03-3.44).
Conclusion: Young women have a high risk of systemic disease even when diagnosed in an early stage. The excess risk of relapse is most pronounced in Luminal B tumors, where low age is an independent prognostic factor of DDFS and LRFS.
Keywords: Breast cancer; Early stage; Luminal B; Population-based; Prognosis; Subtype; Young age.