Understanding the Cognitive Side Effects of Cancer and Its Therapies


TERMS SUCH AS “COGNITIVE DIFFICULTIES” are clinical descriptions for what most patients with cancer refer to as chemo brain — trouble with focus and memory that can arise because of the disease and its treatments. As a clinician and scientist, I try to be objective and avoid terms that evoke emotion over facts. However, I freely use “chemo brain” in conversations with my patients because it is more genuine, and it is a real concern for anyone receiving cancer therapy, particularly chemotherapy. 

In addition, we don’t have all the facts about chemo brain. It is more of a concept than an evidence-based phenomenon, because we simply don’t understand it fully. It is very difficult to define and measure, because conditions such as anxiety and depression, which often accompany a diagnosis of cancer, can interfere with the tests that measure cognition, as can treatment-related biological changes, particularly menopausal symptoms and altered levels of cortisol or thyroid hormone. We know that chemotherapy affects the way a brain functions because of what we see on basic imaging tests, but we don’t know how or for how long. We may not fully appreciate the real-life impact it might have. Does it affect job performance? Does it affect one’s personality? Is it just a nuisance? 

In these pages of CURE®, you will learn about the science, clinical aspects and patient perspectives associated with the charged subject of chemo brain. It is important that your oncologist be able to freely converse with you about this issue, despite its unknowns. Although it may be more difficult to weigh the pros and cons of therapy in light of potential chemo brain than when considering other possible side effects, it still should be a part of the equation. This is especially true because numerous strategies may help ease chemo brain once (or if) it arises. 

More research and awareness are necessary in the area of chemo brain. It is critical that this field move forward and that we develop better tools to measure cognitive loss and differentiate it from the emotional and psychological impacts of a cancer diagnosis. Ultimately, this will help us find ways to avoid or at least mitigate chemo brain. 

Professor of Medicine 
Chair, Department of Breast Medical Oncology 
The University of Texas MD Anderson Cancer Center 
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