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Cognitive function after cancer and cancer-related treatment

Mary-Ellen Meadows, PhD, ABPP
Section Editor
Patricia A Ganz, MD
Deputy Editor
Sadhna R Vora, MD


There are now over 13 million cancer survivors in the United States and close to 30 million survivors worldwide. This number is expected to grow due to improvements in cancer screening, increases in life expectancy following definitive cancer treatment, and the aging of the population. Despite these improvements, the late effects of treatment, in particular those related to chemotherapy, have become more concerning to patients. These late effects may include what patients have termed "chemobrain" or "chemofog," which can persist in some patients long after treatment has ended.

This topic will discuss cognitive function changes after cancer treatment, particularly as they relate to chemotherapy. Other issues in cancer survivorship are discussed separately. (See "Overview of cancer survivorship care for primary care and oncology providers".)


The mechanism by which cancer and cancer treatment impacts cognitive function has not been elucidated. Some investigators have proposed that cancer treatment can either shift the trajectory of normal cognitive aging or accelerate the aging process [1]. It is likely that many mechanisms contribute to cognitive decline in cancer patients, including inflammation, direct neurotoxic effects of treatments, and damage to progenitor cells, among others [2].

In addition, the observed cognitive dysfunction in some patients is likely the result of an interaction between multiple factors. As an example, in one review of the literature, the multifactorial nature of cognitive deficits in breast cancer patients was discussed [3]. Factors other than chemotherapy were deemed to be important beyond the impact from surgery or medical therapy. These included psychological states (eg, depression, anxiety), the presence of fatigue or menopause, and other comorbid conditions. The authors highlighted the need for larger studies to better understand both the magnitude and mechanism of cognitive dysfunction in this population.

It is important to note that the incidence of cognitive changes (due to chemotherapy predominantly) has been primarily conducted in patients treated with either hematological or breast malignancies. Earlier studies were retrospective and primarily within a year of undergoing treatment. Later studies have included prospective designs and longer follow-ups, with attempts to identify risk factors for developing chemotherapy-related cognitive changes as well as identify the underlying mechanisms.


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Literature review current through: Sep 2016. | This topic last updated: Feb 9, 2016.
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