Tumor Characteristics and Event Free Survival in Older and Younger Women with Early Breast Cancer

Background: Age, race, body mass index (BMI), breast density, parity, smoking and alcohol use are associated with increased risk for breast cancer. These factors, as well as tumor characteristics, treatment regimens and comorbidities, are analyzed for associations with five-year event free survival (EFS) in a sample of women with Stage I-III breast cancer who received chemotherapy with curative intent. Methods: EFS was defined in terms of breast cancer recurrence, second primary, metastasis, and overall survival. Analyses were stratified by age (under age 65 vs. over age 65). EFS was estimated using the Kaplan-Meier method and compared using a Cox proportional hazard model. Results: In a sample of 821 women, mean age at diagnosis was 54 years, with 75% White and 22% Black. Younger women had higher proportions of Stage II and III tumors (p = 0.005), larger tumor size (p = 0.0004), and higher breast density (p = 0.003). Five-year EFS was 91% among younger vs. 82% among older women (p = 0.0005). In women aged < 65, there were 48 EFS events, and triple negative patients had significantly worse EFS compared to other subtypes (p = 0.003). Smokers also had worse EFS (p = 0.04). In women aged ≥ 65, there were 26 events, and both tumor size (p = 0.02) and mastectomy (p = 0.03) were significant for EFS. Conclusions: In our sample, triple negative subtype, smoking history, tumor size, and surgery type were significantly associated with shorter EFS. Race, BMI, alcohol use, parity, breast density, radiation treatment, and specific chemotherapy regimen were not significant for EFS in either age group.