Prognostic factors in young Japanese women with breast cancer: prognostic value of age at diagnosis.

OBJECTIVE The primary objective of this study was to verify whether breast cancer patients aged <35 at diagnosis have poorer prognoses than those aged 35-39, in other words, to identify the prognostic value of age in younger premenopausal patients under 40 years old. The secondary objective was to assess prognostic factors specific for younger premenopausal patients. METHODS We identified 242 consecutive patients who were diagnosed with stage I-III breast cancer before the age of 40 and underwent surgery between 1990 and 2004. We compared disease-free survival and overall survival in patients aged <35 years and those aged 35-39 years, and evaluated clinicopathological factors associated with disease-free survival or overall survival in each age group and in all patients under the age of 40. RESULTS Ninety-nine (41%) patients were younger than 35 years and 143 (59%) were between 35 and 39 years. No significant difference in disease-free survival or overall survival was found between the two groups. In our cohort of patients under the age of 40, the independent factors associated with poor disease-free survival and overall survival included positive axillary lymph nodes and triple-negative status, but not age at diagnosis. Adverse prognostic factors also did not differ considerably between the two age groups. CONCLUSIONS Age at diagnosis was not an independent prognostic factor in our study. Our findings suggest that other clinicopathological features rather than age should be used to determine individualized treatment courses for breast cancer patients younger than 40 years.