It is well known among oncology specialists that cognitive changes can occur in patients after receiving chemotherapy.  These changes often involve problems with memory and concentration, where the cumulative effects have been dubbed “chemo-brain.”  However, it does not appear to be chemotherapy on its own that causes these cognitive changes.  Studies now suggest that it may be other cancer therapies, surgery, anesthesia, and even genetic predispositions that can result in cognitive problems for cancer survivors.

The Latest on “Chemo-brain”

“Chemo-brain may be a bit of a misnomer,” said Tim Ahles, PhD, who is a behavioral psychologist at Memorial Sloan-Kettering Cancer Center, New York, New York.  Ahles and his colleagues have been studying cognitive changes in cancer survivors and they have found that a majority of patients report problems with short-term memory, difficulties in concentrating, and problems with multitasking.  “Initially, we thought the cognitive changes were all due to chemotherapy, but the newer studies suggest there may be other aspects of cancer treatments that are affecting cognitive function as well.” 

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Radiotherapy, the process surrounding surgical procedures (ie, the use of general anesthesia) and noncytotoxic therapies, such as hormone therapies, may also play a role in the development of chemo-brain. According to Ahles, these problems may also be associated with the actual cancer, as opposed to the therapy being used to combat it.  To this point, Ahles noted, “Twenty to 25% of breast cancer patients have lower cognitive functioning prior to starting treatment, so there may be something about the cancer itself.”

Researchers at the Moffitt Cancer Center in Florida have found that breast cancer survivors who have had chemotherapy, radiation, or both do not perform as well on some cognitive tests as women who have not had cancer.1 The investigators conducted a study with colleagues at the University of South Florida and the University of Kentucky that included 313 women:  62 with stage 0–II breast cancer treated with chemotherapy plus radiotherapy (CT group); 67 who received radiotherapy only (RT group; and 184 with no history of cancer (NC group).


The women in all three groups were within 5 years of age of each other, and the patients with breast cancer were matched with cancer-free women who lived in their same zip codes.  All the women were tested cognitively in terms of processing speed and executive functioning, which are the two domains expected to be most affected by chemotherapy.  The participants were also tested for their verbal abilities.  All the women with cancer were tested 6 months after treatment and then tested again 36 months after completing treatments.  The cancer-free women were also tested at 6 months and then again at 36 months.1