PURPOSE: A substantial literature describes age-dependent variations in breast cancer treatment, showing that older women are less likely to receive standard treatment than younger women. We sought to identify patient and tumor characteristics associated with the nonreceipt of standard primary tumor and systemic adjuvant therapies.

PATIENTS AND METHODS: We studied 1,859 women age 65 years or older with stage I and II breast cancer diagnosed between 1990 and 1994 who were cared for in six geographically dispersed community-based health care systems. We collected demographic, tumor, treatment, and comorbidity data from electronic data sources, including cancer registry, administrative, and clinical databases, and from subjects' medical records.

RESULTS: Women 75 years of age or older and women with higher comorbidity indices were more likely to receive nonstandard primary tumor therapy, to not receive axillary lymph node dissection, and to not receive radiation therapy after breast-conserving surgery (BCS). Asian women were less likely to receive BCS, and African American women were less likely to be prescribed tamoxifen. Although nonreceipt of most therapies was associated with a lower baseline risk of recurrence, an important minority of high-risk women (16% to 30%) did not receive guideline therapies.

CONCLUSION: Age is an independent risk factor for nonreceipt of effective cancer therapies, even when comorbidity and risk of recurrence are taken into account. Information regarding treatment effectiveness in this age group and tools that allow physicians and patients to estimate the benefits versus the risks of therapies, taking into account age and comorbidity burden, are critically needed.