Background: Studies have shown that older women are undertreated for breast cancer. Few data are available on 1) cancer-related death in elderly women age 70 and older with pathologic stage T1a, bN0 breast cancer and 2) on the impact of prognostic factors such as increasing age, hormone receptor status (ER), adjuvant radiation therapy (EBRT), chemotherapy, and ethnicity on cancer-related death. Methods: Patient data from SEER database were extracted. Inclusion criteria: females, age 70 and older, pT1a, bN0 invasive breast cancer, ER positive or negative, adjuvant EBRT or no radiation. Cause-specific survival time recorded for all eligible patients. Log-rank test and multivariate Cox regression analysis used for statistical analysis. Hazard ratios (HR) are presented for cancer-related death. Results: ER negative patients had a greater risk of breast cancer death compared to ER positive patients (adjusted HR = 2.34; p < 0.0001). Stage IB patients had a greater risk of breast cancer death compared to stage IA patients (adjusted HR = 1.26; p = 0.09; trend). Patients with no radiation therapy had a greater risk of breast cancer death compared to patients with radiation therapy (adjusted HR = 1.40; p = 0.003). Older age groups had greater risk of breast cancer death compared to patients age 70-74 (referent category) (adjusted HR’s = 1.41, 1.72, and 3.18 for 75-79, 80-84, and 85+ age groups, respectively) (Table). Race had no effect on survival. Conclusions: Patients age 75 and older with T1a, b N0, ER-negative, breast cancer had increased risk of breast cancer-related death. Adjuvant EBRT showed survival benefit in this elderly patient population. Future randomized studies should focus on adjuvant treatments that will improve cancer-related death in this age group.