Study: “Chemobrain” seen in breast cancer patients up to six months after treatment

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People diagnosed with breast cancer who have or will be treated with chemotherapy

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Checked Breast cancer survivors

Checked Special populations: breast cancer patients who have had or will have chemotherapy

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Many people report memory or concentration problems, commonly known as “chemobrain,” during and after cancer treatment. New research shows that for some breast cancer patients these issues continue 6 months after treatment. Documentation of this well-known effect is a crucial first step in developing ways to limit and treat it. (02/02/17)


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This study is about:

Understanding “chemobrain.”  Researchers wanted to see whether chemotherapy-treated breast cancer patients experience memory and concentration issues, and to begin mapping out the course of this effect.

Why is this study important?

This study attempted to determine the percentage of breast cancer patients who experience cognitive issues after receiving chemotherapy and how long it lasts, so that health care providers can help patients cope with this effect.

Study findings: 

  1. More than one-third (37%) of breast cancer patients who have had chemotherapy report cognitive difficulties 6 months after treatment.

What does this mean for me?

This study suggests that a large number of breast cancer patients who undergo chemotherapy may experience more cognitive difficulties, such as forgetfulness and problems with concentration, than people who are not treated with chemotherapy. This “chemobrain” effect can continue up to 6 months after chemotherapy has been completed. More work needs to be done to understand why this occurs and to identify ways to help patients who experience these difficulties. Patients should talk to their health care providers about this and any other symptoms they have after chemotherapy.

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Questions To Ask Your Health Care Provider

  • Is my treatment likely to affect my memory? 
  • Will these effects improve over time? 
  • People have been commenting that I am slower/forgetful. Is this because of the chemotherapy?
  • Is there anything that I can do to improve my memory? 
  • Are there any medications that I can take to improve my memory?
  • What other treatment side effects should I expect? 

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Study background:

Researchers are beginning to study cancer-related cognitive impairment, commonly referred to as “chemobrain,” in patients with breast cancer. Early studies were small, included different patient populations (for example, patients with different cancers and treatments), could not be applied to a broad population, or did not study the patients for a long period. Michelle Janelsins and colleagues from the University of Rochester Medical Center and other institutions published work in the Journal of Clinical Oncology in December 2016 describing their efforts to try to understand breast cancer patients’ cognitive difficulties after chemotherapy.

Researchers of this study wanted to know:

Do breast cancer patients experience cognitive difficulties after undergoing chemotherapy?

Population(s) looked at in the study:

This study included 581 women from the research base of the National Cancer Institute Community Oncology Research Program (NCORP) at the University of Rochester. The data represented women who:

  • had invasive breast cancer (stages I-III).
  • were scheduled to begin chemotherapy (but not radiation at the same time).
  • did not have metastatic disease.
  • did not previously have chemotherapy.
  • were 21-years-old or older.

The study also included 364 women without cancer who were also recruited by the NCORP. This population included friends and family of the study participants and people who had no relationship with patients in the study.

All participants took the FACT-Cog survey, which addresses the following general areas:

  • Perceived cognitive impairment (“I have had trouble concentrating, I have forgotten names of people soon after being
introduced,” etc.)
  • Perceived cognitive abilities (“My memory is as good as it has always been,” etc.)
  • Impact of cognitive impairment on quality of life (“These things have interfered with my ability to do things I enjoy,” etc.)
  • Cognitive impairment perceived by others (“Other people have told me I seemed to have trouble remembering information,” etc.)

Patients took this survey before chemotherapy, within four weeks of receiving chemotherapy, and six months after chemotherapy. Non-cancer patients were surveyed during the same period.

Study findings: 

  1. Breast cancer patients who have had chemotherapy are more likely to report cognitive difficulties, as measured by the FACT-Cog survey (which includes questions about patients’ forgetfulness, concentration, memory, quality of life, and any “chemobrain” identified by others):
    • 45% of breast cancer patients reported cognitive difficulties within 4 weeks of receiving treatment, compared to only 10% of people without cancer.
    • 37% of breast cancer patients reported cognitive difficulties 6 months after chemotherapy treatment, compared to 14% of people without cancer.


The follow up period of this study was only six months, so it is not known if these symptoms linger even longer in some patients. However, to address this limitation, the researchers report that they are currently observing a small group of breast cancer patients and people without cancer for two years post treatment. 

Additionally, in this study breast cancer patients undergoing chemotherapy were compared to women who did not have cancer, so it not clear whether the memory issues are caused by the stress of facing cancer and its treatment in general or something specific to chemotherapy.  Additionally, more work needs to be done to understand how anxiety, depression and other factors affect cognitive function in this population.


This study suggests that nearly half of breast cancer patients who undergo chemotherapy treatment experience cognitive difficulties (“chemobrain”), with just over one-third of patients reporting symptoms even 6 months after treatment. More work needs to be done to understand why these patients experience “chemobrain,” if this is a long-term effect, and potential ways to prevent “chemobrain” or to help patients who experience it. Meanwhile, patients should discuss any cognitive problems or other symptoms they experience after chemotherapy with their health care providers.

Posted 2/2/17

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