At the Breast Cancer Survivors’ Brain MRI Database Group in Japan, researchers found that the sizes breast cancer patients’ brains were smaller than brains of patients who did not receive chemotherapy."  The differences were found at one year after surgery, but had disappeared by three years."  The areas where smaller sizes were found relate to planning and memory.

Writers have erroneously concluded that the restoration of size equates to restoration of function. As one often hears with respect to physical characteristics,"  "size doesn’t matter.""  As neuroscientists have indicated for years, the neurons (types of brain cells) create pathways in the brain in response to repeated stimulation or interaction with the environment."  Since the brain makes new brain cells, it stands to reason that if chemotherapy has destroyed brain cells, the volume would begin to increase after chemotherapy’s cell destruction has ceased."  However, pathways must be established with the new cells, and it is repetition that creates pathways (remember those multiplication drills in 3rd grade?).

The skills we use in ordinary tasks such as balancing a checkbook and deciding which package of ground beef to purchase are established over years of experience and interaction with our environment."  It is highly doubtful that they can be completely repaired in one to two years. " 

Stroke patients don’t spontaneously rewire their brains for motor or language improvement—physical therapy is needed to accomplish this."  Similarly, the damage caused by chemotherapy will require concerted effort to restore function.

Obviously, studies are needed. My very strong recommendation would be to select or develop meaningful measures of cognitive performance and not just make unwarranted inferences about brain performance based on brain volume.

Article: "Smaller Regional Volumes of Brain Gray and White Matter Demonstrated in Breast Cancer Survivors Exposed to Adjuvant Chemotherapy," Masatoshi Inagaki, Eisho Yoshikawa, Yutaka Matsuoka, Yuriko Sugawara, Tomohito Nakano, Tatsuo Akechi, Noriaki Wada, Shigeru Imoto, Koji Murakami, Yosuke Uchitomi, and the Breast Cancer Survivors' Brain MRI Database Group, CANCER; Published Online: November 27, 2006 (DOI: 10.1002/cncr.22368); Print Issue Date: January 1, 2007.

Summaries of the article:

1)" American Cancer Society website

2)" firstscience.com

3)" Sciencedaily.com