Cognitive functions in brain tumor patients.

As effective treatment interventions have increased survival rates, there has been greater awareness that many brain tumor patients experience cognitive dysfunction despite adequate disease control. Cognitive difficulties often have an impact on quality of life and interfere with the patient's ability to function at premorbid levels; however, the incidence of cognitive dysfunction in brain tumor patients is unknown, because it has not been investigated systematically. Future prospective clinical trials in neuro-oncology should include cognitive outcome measures to increase understanding of the contribution of the tumor and the delayed effects of treatment to cognitive dysfunction.