Chemotherapy is a crucial cancer treatment that has extended the lives of thousands of Americans.

The therapy involves introducing chemicals into the body that are toxic to cancer, and it can produce unpleasant side effects in some patients.

Some of these side effects, such as hair loss and feelings of nausea, are well-documented.

Oncologists are skeptical about other side effects, including the mental fuzziness, poor concentration and memory loss collectively referred to as “chemobrain” [KEY-mo-brain].

However, new findings support the idea that chemotherapy takes its toll on the brain in some patients.

A Japanese research team used high-resolution imaging techniques to compare the brains of fifty-one women who received chemotherapy for breast cancer with those of fifty-four breast cancer patients who had only surgery.

The scientists reported in the journal Cancer that one year after treatment, key areas of the brain had actually shrunk in the women who had chemotherapy.

The women who suffered the most volume loss had more difficulty in tests of concentration and memory.

While the findings may lend additional scientific support to the concept of “chemobrain,” chemotherapy remains in many cases the best chance a patient has to recover.

Fortunately, the human brain is remarkably resilient. Brain scans showed that the women who received chemotherapy recovered their lost brain volume three years after treatment.

But the next step for scientists is to find ways to shield the brain from the toxic effects of chemotherapy and to develop drugs that more accurately target cancer.