A subset of breast cancer survivors are reporting cognitive impairment after cancer treatment, which has commonly been attributed to the receipt of chemotherapy and colloquially termed "chemobrain." For some, a fear of this side effect enters into their decision regarding therapy. Our review of the literature reveals that so-called "chemobrain" is complex and that factors other than chemotherapy may affect cognitive function, including the impact of surgery and anesthesia, hormonal therapy, menopause, anxiety, depression, fatigue, supportive care medications, genetic predisposition, comorbid medical conditions, or possibly paraneoplastic phenomenon. Studies to date have differed in their assessment and definition of cognitive impairment, thus, making comparisons between studies difficult. In addition, most studies have been limited by a small sample size, and there has been a general lack of focus on older patients despite their high concentration within the cancer population. Large, multicenter studies are needed to better understand the magnitude and mechanism of cognitive changes in cancer survivors and to assess the impact of cognitive changes on the patient's daily lives. We propose that the phenomenon commonly referred to as "chemobrain" would be more accurately labeled "cancer- or cancer-therapy-associated cognitive change."
