Risk of subsequent dementia diagnoses does not vary by types of adjuvant chemotherapy in older women with breast cancer

Abstract

Little is known about long-term cognitive side effects of adjuvant chemotherapy for breast cancer. We thus examined incidence of dementia diagnoses in older women diagnosed with breast cancer, stratified by types of chemotherapy regimen. We identified patients with incident dementia diagnoses through Medicare claims linked to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) tumor registry data. The study population (n = 6,932) consisted of women at least 68 years of age, who were diagnosed with early-stage breast cancer from 1994 through 2002 in one of the SEER areas and received chemotherapy as part of their cancer treatment. Excluded were women with a diagnosis of dementia within the 3 years prior to their cancer diagnosis. Our sample comprised mostly white women. The mean age was 74. Fifty-seven percent were estrogen receptor positive. Over 70% had no comorbidity. The use of taxol and anthracycline-based treatments increased from mid-1990s to early 2000. Increasing age at cancer diagnosis, Black ethnicity, living in a census tract with lower level of education, and increasing number of comorbidities were associated with new claims of dementia diagnoses after chemotherapy. There was no significant association between types of chemotherapy agents and risk of subsequent dementia diagnoses. No association was found between types of adjuvant chemotherapy agents for breast cancer and risk of new dementia diagnoses. Our findings suggest that concerns about post-chemotherapy dementia should not be a major factor in determining type of adjuvant chemotherapy regimen to prescribe for older women with breast cancer.