Neurocognitive performance in breast cancer survivors exposed to adjuvant chemotherapy and tamoxifen

Abstract

The primary aim of the current study was to examine whether neurocognitive functioning among breast cancer survivors (BCS) exposed to systemic adjuvant chemotherapy differs from that seen among BCS who did not receive chemotherapy. The performance of each of these BCS groups was compared to a demographically matched comparison group without history of breast cancer, a group not included in the majority of previous cognitive functioning studies. We also sought to explore whether usage of the anti-estrogen drug tamoxifen, a common component of breast cancer treatment, was related to neurocognitive functioning. Finally, we wished to examine the relationship between subjective report of cognitive functioning and objective performance on neurocognitive measures among BCS. Fifty-three survivors of breast cancer (all between 2-5 years after diagnosis and initial surgical removal of cancerous tissue) and 19 healthy non-BCS comparison subjects were administered a comprehensive neurocognitive battery, and measures of mood, energy level, and self-reported cognitive functioning. Those BCS who received adjuvant chemotherapy performed significantly worse in the domains of verbal learning, visuospatial functioning, and visual memory than BCS treated with surgery only. Those who received both chemotherapy and tamoxifen showed the greatest compromise. Although patients who received chemotherapy (with and without tamoxifen) performed worse than those treated with surgery only on several domains, neither group was significantly different from demographically matched comparison subjects without a history of breast cancer. Finally, we found no relationship between subjective cognitive complaints and objective performance, although cognitive complaints were associated with measures of psychological distress and fatigue. We highlight ways in which these data converge with other recent studies to suggest that systemic chemotherapy, especially in combination with tamoxifen, can have adverse yet subtle effects on cognitive functioning.