Understanding why older women with breast carcinoma do not receive definitive treatment is critical if disparities in mortality between younger and older women are to be reduced. With this in mind, the authors studied 302 women age > or =55 years with early stage breast carcinoma. Data were collected from surgical records and in telephone interviews with the women. The main outcome was receipt of definitive primary tumor therapy, defined either as modified radical mastectomy or as breast-conserving surgery with axillary dissection followed by radiation therapy. The majority (56%) of the women underwent breast-conserving surgery and axillary dissection followed by radiation therapy. After statistical control for four variables (comorbidity, physical function, tumor size, and lymph node status), patients' ages, marital status, and the number of times breast carcinoma specialists discussed treatment options were significantly associated with the receipt of definitive primary tumor therapy. The authors concluded that when older women have been newly diagnosed with breast carcinoma and there is clinical uncertainty as to the most appropriate therapies, patients may be better served if they are offered choices from among definitive therapies. In discussing therapies with them, physicians must be sensitive to their fears and concerns about the monetary costs and functional consequences of treatment in relation to the expected benefits.