Purpose: Numerous studies have demonstrated that breast cancer in young women (BCY) has unfavorable prognostic features and more unfavorable subtypes. However, few studies have evaluated the effect of subtype disparities on breast cancer prognosis by age, especially for BCY. We analyzed breast cancer mortality stratified by tumor subtype according to age among patients younger than 50 years.
Methods: Data from the Korean Breast Cancer Society Registry for patients diagnosed with invasive breast cancer when aged less than 50 years between 2003 and 2010 were reviewed retrospectively.
Results: We identified 30,793 patients with breast cancer who were eligible for analysis. Of these, 793 (2.6%) were aged 20-29 and 8926 (28.8%) were aged 30-39. Median follow-up duration was 84 months. Mean age was 42.4 years. Patients in their 20s were more likely to have cancer of advanced stage and higher nuclear grade, present with lymphovascular invasion, and have unfavorable subtypes. Patients in the 20s group showed worse prognosis. In multivariate analysis for overall survival (OS), the hazard ratio (HR) for patients in the 20s group was higher than that for the 30s and 40s groups, and patients with triple-negative breast cancer (TNBC) showed higher HR than patients with HER-2 or luminal subtype (all p < 0.0001). When stratified by subtype, luminal subtype showed significantly worse prognosis in the 20s group than the 30s and 40s groups, whereas HER-2 and TNBC subtypes showed no significant difference.
Conclusion: Patients in their 20s with breast cancer had unfavorable characteristics and worse prognosis than patients in their 30s and 40s. When stratified by tumor subtype, patients in their 20s with luminal subtype of breast cancer showed worse prognosis than older patients, whereas HER-2 and TNBC subtypes showed no significant differences.
Keywords: Breast neoplasms; Intrinsic subtype; Prognosis; Young women.