Modifiable factors and cognitive dysfunction in breast cancer survivors: a mixed-method systematic review

It is unknown why some breast cancer survivors experience cancer-related cognitive impairments (CRCI) after cancer treatment, and modifiable risk factors for CRCI remain to be explicated. This mixed-method systematic review synthesizes quantitative and qualitative evidence for relationships between modifiable factors and CRCI in breast cancer survivors who receive chemotherapy as part of their treatment. Keyword Searches of PubMed/Medline, PsychINFO, and CINAHL were performed for January 2005 through June 2015. Studies that provided data on associations between modifiable biological, behavioral, environmental, and psychosocial factors and cognition were included. Twenty-two quantitative studies and five qualitative studies were identified after applying inclusion and exclusion criteria yielding evidence for significant relationships among modifiable biological (inflammatory cytokines), behavioral (sleep quality, physical activity), and psychosocial (stress, distress, affect) factors and CRCI. Many women unfortunately experience CRCI after breast cancer chemotherapy, with limited treatment options available to improve cognitive function. This review synthesizes current evidence to support the associations between modifiable factors and CRCI and can inform research to evaluate these factors prospectively. The clinical implications of these findings suggest that lifestyle factors such as physical activity, stress management, and sleep quality may be appropriate targets for behavioral interventions to improve cognitive function following breast cancer chemotherapy; however, further research is necessary.