Review article

Breast Cancer

, Volume 12, Issue 4, pp 279-287

First online:

Mild cognitive impairment after adjuvant chemotherapy in breast cancer patients - evaluation of appropriate research design and methodology to measure symptoms

  • Tomohiro MatsudaAffiliated withDepartment of Epidemiology, National Institute of Public Health Email author 
  • , Tomoko TakayamaAffiliated withFaculty of Health Sciences, Okayama University Medical School
  • , Manabu TashiroAffiliated withCyclotron and Radioisotope Center, Tohoku University
  • , Yu NakamuraAffiliated withDepartment of Psychiatry, Faculty of Medicine, Kagawa University
  • , Yasuo OhashiAffiliated withDepartment of Biostatistics, School of Health Sciences and Nursing, University of Tokyo
  • , Kojiro ShimozumaAffiliated withDepartment of Healthcare and Social Services, Faculty of Service Industries, University of Marketing and Distribution Sciences

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The development of new chemotherapeutic agents and regimens has contributed to reduced risk of cancer recurrence and prolonged patient survival. However, mild cognitive impairment (MCI), also known as “chemofog” or “chemobrain” following adjuvant chemotherapy for breast cancer has been reported since the late 1980s. Unfortunately, little is known about it's mechanism, type, severity, and episode length. This article reviewed related studies on the subject, and found that chemotherapy-induced MCI appears to occur in 10-40% of patients, and memory loss and lack of concentration are the most frequent symptoms. The symptoms are apparently transient, but take at least several years to disap-pear. Reviewed studies show a lack of clear understanding of what causes MCI directly. There is also a lack of consistency in symptom measurement. We point to the need to conduct well-designed studies which begin with a proper hypothesis. Future research needs to be randomized and longitudinal with a base measurement point before the chemotherapy cycle starts. Future studies must adopt an effective and sensitive method to measure MCI. The latest imaging technique, positron emission tomography (PET) may be a powerful tool. Also, all confounding factors, such as age, education, intelligence quotient (IQ), fatigue and depression, hormonal therapy and other treatments should be controlled within the study design. It is hoped that the results of such future studies will allow medical professionals to contemplate effective prevention, treatment and rehabilitation for MCI.


Cognitive impairment Chemotherapy Breast cancer QOL PET