Clinical Significance of Age at the Time of Diagnosis among Young Breast Cancer Patients

PURPOSE: The aims of this study were to investigate outcomes corresponding to age at diagnosis as categorized into 5-year intervals and to explore whether endocrine-responsive tumors display clinical benefits from endocrine therapy after chemotherapy among young breast cancer patients. METHODS: A total of 1,171 patients who were under 40 years old at diagnosis between 1985 and 2007 were divided into 3 subgroups: ≤30 years (Group I, 13.3%), 31-35 years (Group II, 30.5%), and 36-40 years (Control group, 56.2%). Clinicopathological factors and outcomes were compared using a chi-square test, the Kaplan-Meier method, and Cox's hazards models. RESULTS: There were no significant differences in the characteristics and treatment patterns between the 3 groups, except for the grade, hormone receptors expression, and use of endocrine therap. Group I showed the worst survival and subsequently Group II presented worse outcomes than the Control group, mainly among hormone receptors-positive patients. Groups I and II showed increased risks of recurrence and death in multivariate analyses. Among 529 hormone receptors-positive patients who received chemotherapy, favorable outcomes for patients who were treated with endocrine agents were demonstrated, mainly in patients aged 35 years or less. However, interaction tests between the use of endocrine therapy and age at diagnosis were not significant. CONCLUSION: Age at diagnosis is an independent prognostic factor and the age of 35 years is a rational cut-off among young patients. Our subgroup analysis suggests that endocrine therapy may provide additional benefits even in young breast cancers. Therefore, further researches should be directed towards improving outcomes for this population.