The term chemotherapy-related cognitive impairment (CRCI), or cognitive dysfunction, or chemo fog, or chemo brain, is referred to a decline in a variety of neuropsychological tasks after chemotherapy, or following other anticancer treatments such as radiation therapy or surgery, in patients with non-central nervous system cancers. Furthermore, several pieces of evidence suggest that clinical manifestations of cognitive impairment may occur in cancer patients, prior to chemotherapy or in those not treated with cancer therapies. In these circumstances, it should be more appropriate to use the term cancer-related cognitive dysfunction. Because there is no consensus about its definition and diagnostic criteria, no specific test for CRCI diagnose exists. Whatever the cause, this manifestation of central nervous system toxicity is of increasing concern as the survival rates for cancer have improved steadily and, in turn, cognitive dysfunction can negatively impact the patients and cancer survivors' quality of life. The aim of this work is to offer an overview of the topic and recommendations for future research.