Chemobrain: a translational challenge for neurotoxicology

Abstract

Neurotoxicity is a frequent accompaniment of cancer chemotherapy, and held by many oncologists to be the major dose-limiting side effect. It appears in many forms, but attracted attention during the past decade primarily because of complaints by patients of impaired cognitive function they have labeled as "chemobrain". Neuropsychological testing confirmed the validity of these complaints and has generated a substantial literature examining different aspects of cognitive impairment in various clinical populations undergoing a variety of treatments. Cognitive impairment is far from the only manifestation of neurotoxicity induced by chemotherapy, however. It alters sensory function and motor function as well. A critical need for patients is a suite of methods that will enable clinicians to trace the onset and progression of neurotoxicity so as to guide and balance decisions about the course of chemotherapy. This commentary describes some of the potential methods and encourages neurotoxicologists to enlist their unique skills in the service of these needs.

Figure 1

Cancer survival 1971–2003. Over this period, the number of survivors has increased markedly. By 2020, the estimated number of world-wide survivors will exceed 70,000,000.

Figure 2

Subjective reports of memory difficulties in patients undergoing chemotherapy for breast cancer (based on data from Hurria et al., 2006).

Figure 3

Neuropsychological tests used to investigate cognitive impairments in cancer patients undergoing chemotherapy.

Figure 4

Tests for visual contrast sensitivity. Left: Mars Test Chart; contrast diminishes left to right, up to down. Right: online sample from Functional Acuity Contrast Test, (Stereo Optical Co., Chicago, IL).