No link found between chemotherapy in older women with breast cancer and later cognitive impairment
Contrary to the findings of several small-scale clinical trials linking chemotherapy to later cognitive impairment, a new study of older women diagnosed with breast cancer did not find significantly increased risk of cognitive impairment up to 16 years after chemotherapy. Researchers from the University of Texas Health Science Center found that an apparent 8 percent increase in drug-induced dementia with chemotherapy was not significant after adjustment for patient and tumor characteristics; nor was a possible 15 percent decline in cognitive disorder not otherwise specified (NOS). In fact, the data for the entire study group suggests that the women who received chemotherapy were 23 to 28 percent less likely to develop Alzheimer's disease, vascular dementia, or other dementias/dementia NOS than women not treated with chemotherapy.
The researchers used the merged database of the National Cancer Institute's Surveillance, Epidemiology, and End-Results program and Medicare, which increased coverage of the U.S. population from 14 to 25 percent over the course of the study. The study group was 62,565 women aged 65 or older diagnosed with breast cancer and free from cognitive impairment at the time of their cancer diagnosis. A subset of 9,752 women who received chemotherapy and an equal number who did not were matched on the factors that make treatment with chemotherapy likely at diagnosis. The study was funded in part by the Agency for Healthcare Research and Quality (HS16743).
More details are in "Relationship between chemotherapy use and cognitive impairments in older women with breast cancer. Findings from a large population-based cohort," by Xianglin L. Du, M.D., Ph.D., Rui Xia, M.S., and Dale Hardy, Ph.D., in the December 2010 American Journal of Clinical Oncology 33(6); pp. 533-543.
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