PURPOSE: There is no concensus on the type of therapy useful for elderly cancer patients. Since 2000, Korea has become an elderly society. This study aims to assess clinical characteristics of elderly breast cancer women, and to evaluate determinants and effects of treatment choice for breast cancer prognosis among elderly patients. METHODS: We reviewed the clinical reports of 123 breast cancer patients aged > or =70 yr recorded at the Asan Medical Center Breast Cancer Registry between 1992 and 2002. Patient and tumor chariteristics, comorbidity, surgical method, adjuvant therapy and cause of death were taken into consideration. Survival analysis was determined according to the treatment method. RESULTS: The median time to diagnosis was 33.6 months. Only 9 patients (5.1%) were diagnosed in the screening program. A modified radical mastectomy was performed for 74 patients (60.1%), Breast conserving surgery was performed for 26 patients (24.7%), and there was no further curative therapy for 12 patients (9.7%). 32 patients (38.1%) had axillary lymph node metastasis. The median follow-up duration was 43.1 months; the overall survival rate was 71.8%, and the disease free survival rate was 65.4%. Breast cancer related mortality was 62.8%. CONCLUSION: Delayed diagnosis and infrequent screening were frequent among elderly patients. Cancer related morbidity was less than general breast cancer patients. Treatment needs to be adapted to the general health status of the patient and comorbid conditions, but has to offer the best chance of cure, regardless of age.