Longitudinal assessment of cognitive changes associated with adjuvant treatment for breast cancer: impact of age and cognitive reserve.

PURPOSE: To examine the impact of age and cognitive reserve on cognitive functioning in patients with breast cancer who are receiving adjuvant treatments. PATIENTS AND METHODS: Patients with breast cancer exposed to chemotherapy (n = 60; mean age, 51.7 years) were evaluated with a battery of neuropsychological and psychological tests before treatment and at 1, 6, and 18 months after treatment. Patients not exposed to chemotherapy (n = 72; mean age, 56.6 years) and healthy controls (n = 45; mean age, 52.9 years) were assessed at matched intervals. RESULTS: Mixed-effects modeling revealed significant effects for the Processing Speed and Verbal Ability domains. For Processing Speed, a three-way interaction among treatment group, age, and baseline cognitive reserve (P < .001) revealed that older patients with lower baseline cognitive reserve who were exposed to chemotherapy had lower performance on Processing Speed compared with patients not exposed to chemotherapy (P = .003) and controls (P < .001). A significant group by time interaction for Verbal Ability (P = .01) suggested that the healthy controls and no chemotherapy groups improved over time. The chemotherapy group failed to improve at 1 month after treatment but improved during the last two follow-up assessments. Exploratory analyses suggested a negative effect of tamoxifen on Processing Speed (P = .036) and Verbal Memory (P = .05) in the no-chemotherapy group. CONCLUSION: These data demonstrated that age and pretreatment cognitive reserve were related to post-treatment decline in Processing Speed in women exposed to chemotherapy and that chemotherapy had a short-term impact on Verbal Ability. Exploratory analysis of the impact of tamoxifen suggests that this pattern of results may be due to a combination of chemotherapy and tamoxifen.

Cognitive function in breast cancer patients prior to adjuvant treatment.

PURPOSE: To compare the neuropsychological functioning of breast cancer patients with invasive cancer and noninvasive cancer prior to adjuvant treatment. PATIENTS AND METHODS: Breast cancer patients (N = 132) with invasive (Stages 1-3, N = 110, age = 54.1 +/- 8.1) or noninvasive (Stage 0, N = 22, age = 55.8 +/- 8.0) disease completed a battery of neuropsychological and psychological instruments following surgery but prior to initiation of chemotherapy, radiation or hormonal therapy. Matched healthy controls (N = 45, age = 52.9 +/- 10.0) completed the same battery of instruments. For the patients, data on menstrual status, type of surgery, time of general anesthesia, CBC and platelets, nutritional status (B12 and folate), and thyroid function were collected. RESULTS: Comparison of mean neuropsychological test scores revealed that all groups scored within the normal range; however, patients with Stage 1-3 cancer scored significantly lower than healthy controls on the Reaction Time domain (p = 0.005). Using a definition of lower than expected cognitive performance that corrected for misclassification error, Stage 1-3 patients were significantly (p = 0.002) more likely to be classified as having lower than expected overall cognitive performance (22%) as compared to Stage 0 patients (0%) and healthy controls (4%). No differences were observed between patients classified as having lower than expected cognitive performance compared to those classified as normal performance on measures of depression, anxiety, fatigue, menstrual status, surgery/anesthesia or any of the blood work parameters. CONCLUSION: Patients with Stage 1-3 breast cancer were more likely to be classified as having lower than expected cognitive performance prior to adjuvant treatment as compared to Stage 0 patients and healthy controls, although correction for misclassification error produced a lower rate than previously reported.