In recent years, we have seen a significant increase in the incidence and prevalence of oncological diseases. With the evolution of treatments and the tendency to increase the life expectancy of cancer patients, it is necessary to consider even more: not only survival but also the quality of life in this period, with the individual being able to maintain their family, social, and labor activities. An important and often neglected cause of impact on quality of life, functionality, and work capacity is cancer-related cognitive impairment, which arises from several etiologies, with chemotherapy being one of the most common. This chapter reviews the literature on cognitive dysfunction associated with chemotherapy and how to evaluate and clinically manage patients with this important complication, providing a clear and didactic text on the topic for health professionals who deal with cancer patients in their clinical practice or who are interested in studying and researching the theme.
Top2. Concepts And Epidemiology
It is already well documented that patients undergoing chemotherapy can suffer cognitive changes, which can be subjective (when there is only the patient's complaint without dysfunction proven by tests) and objective (with documentation of impairment by cognitive tests), mainly in short term memory, attention, executive functions, and processing speed (Ahles et al., 2012; Fleming et al., 2023; Joly et al., 2015; Lange et al., 2019; Pendergrass et al., 2018). In the literature, these changes were called chemotherapy-related cognitive impairment, or colloquially “chemobrain.”
Studies demonstrate “chemobrain” in neoplasms such as colorectal cancer, lung cancer, ovarian cancer, testicular cancer, and lymphoma, but this phenomenon has been much more studied in patients with breast cancer (Fayette et al., 2023; Fleming et al., 2023; Lange et al., 2019; Whittaker et al., 2022). Cognitive changes seem more critical during the chemotherapy period, generally with improvement over time, but this improvement is only partial in about a third of cases (Collins et al., 2014). Data from cross-sectional studies indicate rates of 16 to 75% of moderate or severe cognitive impairment during the period of chemotherapy for breast cancer, compared with 4 to 11% in controls (Brezden et al., 2000; Janelsins et al., 2011; Tchen et al., 2003). It is essential to mention that this classification as moderate to severe in these studies was based on scores in cognitive tests and not directly on functionality, having no relation in size to what occurs, for example, in moderate to severe dementias, when even basic activities of daily living tend to be compromised. In the cognitive decline associated with chemotherapy, even in more severe cases, what usually happens are difficulties in instrumental activities of daily living. A more recent meta-analysis on chemotherapy-related cognitive impairment in breast cancer patients estimated its prevalence using self-report, short cognitive screening tools, and neuropsychological test batteries at 44%, 16%, and 21–34%, respectively (Whittaker et al., 2022).