According to data largely obtained from retrospective studies, it has been postulated that chemotherapy exerts an aggravating effect on the cognitive function of patients with breast cancer. Potential individual factors related to the effects of chemotherapy on cognitive function have been indicated, such as age-related cognitive dysfunction and stress. Elderly patients differ from non-elderly patients as regards higher cognitive related comorbidities, such as dementia, as well as regarding lower stress levels, indicating that 'chemobrain' may differentially affect these two age groups. The aim of this review was to discuss the effects of stress and chemotherapy on cognitive dysfunction and identify any potential age-related differences in patients with breast cancer treated with adjuvant chemotherapy. For this purpose, a systematic review of the literature was carried out on the PubMed, Scopus and Web of Science databases. The inclusion criteria were original articles published in peer-reviewed journals, elderly and non-elderly patients with breast cancer, reporting on stress and at least one cognitive parameter pre- and/or post-treatment. Eight studies met the preset criteria and were further analyzed. In total, the data of 1,253 women were included, of whom 800 patients with breast cancer were treated with surgery only, systemic treatment only, or both. Although all the studies included a non-elderly breast cancer patient subpopulation, only two of the studies included patients over 65 years of age. All studies indicated a statistically significant association of stress with various domains of cognitive dysfunction in patients, as shown by either self-completed questionnaires, neuropsychological testing or both. An age over 60 years was linked to fewer cognitive difficulties mediated by lower levels of stress. Thus, the evidence supports the association of stress with cognitive deficits in patients with breast cancer, regardless of the type of cancer-related treatment. Therefore, stress should be appropriately addressed. However, further research is required to investigate the association of stress with cognitive function in elderly patients with breast cancer.
Keywords: breast cancer; chemotherapy; cognitive function; geriatric; stress; ‘chemobrain’.