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Cognitive function unaffected by SERMs in postmenopausal women at high risk for breast cancer
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Raloxifene and tamoxifen did not show any significant effects on cognitive function among postmenopausal women at high risk for breast cancer, according to data from the Cognition in the Study of Tamoxifen and Raloxifene trial. However, the researchers did observe a trend toward higher cognitive function scores among women treated with raloxifene compared with tamoxifen.
Based on results from previous studies, researchers hypothesized that compared with tamoxifen, raloxifene would be associated with greater cognitive benefits. Using data from the National Surgical Adjuvant Breast and Bowel Project’s Study of Tamoxifen and Raloxifene (STAR) study, a multicenter, randomized trial comparing tamoxifen 20 mg per day to raloxifene 60 mg per day for a maximum of five years in postmenopausal women aged 35 and older, the researchers conducted Co-STAR. The study began 18 months after STAR began enrolling and included 1,498 patients who were administered a cognitive test battery modeled after the one used in the WHI Study of Cognitive Aging. Patients were assessed three times at about 12-month increments.
In addition, 273 patients who completed their first cognitive battery prior to beginning treatment in the STAR trial were assessed.
According to the researchers, there was no statistically significant difference in mean cognitive measures among the treatment groups at initial assessment; this was true across visits. However, the measure for difficulty learning a new word list after having been exposed to a primary word list was higher in the raloxifene group compared with tamoxifen (P=.04). In addition, women in the raloxifene group aged 70 and younger had higher letter fluency scores compared with older women (40.7 vs. 37.8). There was no difference in the tamoxifen group.
Changes in global cognition, verbal and visual memory, visuospatial skills, verbal knowledge, Positive and Negative Affect Schedule (PANAS)-positive and general depression were observed over the study period, independent of treatment. PANAS-positive affect was higher for the raloxifene group compared with the tamoxifen group (P=.01). Over two-years of follow-up, there was a trend toward higher positive affect in the raloxifene group compared with tamoxifen (P=.06).
“In summary, the good news is that in older women considering the use of either tamoxifen or raloxifene for the prevention of breast cancer, there is no evidence of serious cognitive changes that would preclude their use,” Steven A. Castellon, PhD, of Greater Los Angeles Veterans Affairs Healthcare System and David Geffen School of Medicine at UCLA, and Patricia A. Ganz, MD, of Jonsson Comprehensive Cancer Center at UCLA Schools of Medicine and Public Health, wrote in an accompanying editorial. “The choice of which drug to use for high-risk women should be determined by other medical factors and quality of life issues.”
In addition, the authors note that more research is needed in early postmenopausal women to determine the cognitive effects of SERMs and decide whether both tamoxifen and raloxifene have similar effects in comparison to untreated controls.
Legault C. J Clin Oncol. 2009;doi:10.1200/JCO.2008.21.0716
