Chemotherapy temporarily affects human brain, study shows

Patients receiving chemotherapy have often complained of problems with memory, problem-solving and other cognitive abilities. Although chemotherapy was thought not to affect brain cells due to the blood-brain barrier, recent clinical studies have confirmed declines in cognitive functions in patients receiving chemotherapy. Animal studies have shown physical changes in the brain and in neurons caused by chemotherapy drugs.

In human studies, however, the little data that is available is only available through imaging and is not consistent in the long term. In addition, lack of controls in studies makes it difficult to discern cancer versus drug-effects.

Conducted by Breast Cancer Survivors’ Brain MRI Database Group in Japan, researchers used MRI to take high-resolution images and measure volumes in specific areas of the brain of breast cancer patients who received chemotherapy and those who did not one year after surgery and three years after surgery. In addition, they compared brains of cancer survivors’ one year after surgery and three years after surgery with healthy subjects.

They found that at one year, patients treated with chemotherapy had smaller volumes in cognitively sensitive areas. However, at three years post-surgery there were no volume differences. That there were no differences between cancer patients and healthy controls at any time point demonstrates that there is no observable cancer-effect in cognitive deficits.

The authors conclude that “these results lead to the idea that adjuvant chemotherapy could have a temporary effect on brain structure.”