Abstract 4129: Outcome disparities in breast cancer of the young: Is young age at diagnosis associated with unique disease biology
Authors: Valente Allyson L. , Hueman Matthew T. , Shriver Craig D. , Ellsworth Rachel E. 
Published: May 2015

Background: Although breast cancer in young women (YW) only accounts for ∼7% of cases diagnosed annually, tumors in young patients have more aggressive characteristics and higher mortality rates. The cost of breast cancer increases significantly with more aggressive tumors in terms of treatment costs, physical and psychosocial effects on the patient and her family, and lost productivity. Improved understanding of factors associated with etiology and outcome of breast cancer in YW is critical to developing more effective prevention strategies and improved treatments, reducing the burden of breast cancer in this population.

Methods: The Clinical Breast Care Project (CBCP) database was queried to identify all female patients with invasive breast cancer diagnosed before 40 years (YW) and between 50-65 years (post-menopausal women, PMW). Pathological characteristics from both groups were compared using chi-square analysis with P&lt;0.05 defining significance. Gene expression data was generated using U133 2.0 arrays from tumors from a subset of 76 patients matched by subtype, grade and stage. ANOVA analysis was used to detect differentially expressed genes with a False Discovery Rate &lt;0.05, 2-fold difference used to define significance.

Results: YW represented 6% (89/1434) of the female invasive cancer population of the CBCP. YW were significantly more likely to be of African American ancestry (27%) compared to PMW (14%). Tumors from YW were significantly more likely to be hormone receptor negative, higher stage and grade, larger and more likely to have positive lymph node status and significantly less likely to be ER+/HER2-. Cancer mortality rates were significantly higher in YW (12%) compared to PMW (3%). Gene expression analysis, however, failed to identify any differentially expressed genes in subtype, grade and stage-matched tumors between YW and PMW.

Conclusions: Outcomes in YW with breast cancer are less favorable than those in PMW. Gene expression analysis suggests that tumors from YW are not molecularly different from those from PMW and thus tumors from YW do not represent a unique disease entity. Rather, higher stage and tumor size at diagnosis due to lack of screening in combination with increased incidence of more aggressive subtypes is likely driving higher mortality rates. Identification of epidemiological and/or genetic factors contributing to the etiology of aggressive tumors in conjunction with evaluation of possible treatment differences may reduce outcome disparities by decreasing the incidence of and improving treatment for breast cancer in young women.

Citation Format: Allyson L. Valente, Matthew T. Hueman, Craig D. Shriver, Rachel E. Ellsworth. Outcome disparities in breast cancer of the young: Is young age at diagnosis associated with unique disease biology. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4129. doi:10.1158/1538-7445.AM2014-4129