Breast cancer tumor histopathology, stage at presentation, and treatment in the extremes of age

Background Given presumed differences in disease severity between young (<= 45 years) and elderly (>= 75 years) women with breast cancer, we sought to compare tumor histopathology, stage at presentation, patterns of care, and survival at the extremes of age. Methods Adults with stages 0-IV breast cancer in the National Cancer Database (2004-2015) were categorized by age (18-45 years, 46-74 years, >= 75 years) and compared. Kaplan-Meier curves were used to visualize unadjusted overall survival (OS). A Cox proportional-hazards model was used to estimate the effect of age group, including adjustment for tumor subtype [hormone receptor [HR]+/HER2-, HER2+, triple-negative (TN)]. Results Of the 1,201,252 patients identified, 13% were <= 45 years and 17.5% were >= 75 years. Women <= 45 years were more likely to have higher pT/N stages and grade 3 disease compared to older patients; however, rates of de novo cM1 disease were comparable (3.7% vs 3.5%). HER2+ and TN tumors were more common in those <= 45 years (HER2+ : 18.6% vs 9.2%; TN: 14.9% vs 8.2%), while HR+/HER2- tumors were more likely in women >= 75 years (69.3% vs 51.3%) (all p < 0.001). Younger patients were more likely to undergo mastectomy vs lumpectomy (56% vs 34%), and receive chemotherapy (65.8% vs 10.2%) and radiation (56.2% vs 39.5%). After adjustment, OS was worse in older patients (older HR 2.94, CI 2.86-3.03). Conclusions High-risk tumor subtypes and comprehensive multimodal treatment remain significantly more common among younger women (<= 45 years) with breast cancer, yet, elderly women are similarly diagnosed with incurable de novo metastatic disease. Tailored screening and treatment strategies are critical to prevent age-related disparities in breast cancer care.