Dr. C. Joseph Bennett, Navigating Cancer, 01/08/13

As I discussed last week, at this time of the year, we all have made resolutions of what we want to accomplish in this New Year.

Many times, I have discussed the obesity epidemic in this country, and the risk it poses to our health from many different aspects. Now, laboratory test data suggest that obesity after menopause may actually promote the development and growth of breast cancer.

In this study, researchers found excess nutrients associated with menopausal weight gain are deposited into the breast tumors of rats that were already obese before menopause.

Yes, you read that correctly, rats; this is a laboratory experiment that may shed some light on human breast cancer, but still it is a lab study with rats, so it must be taken with a grain of salt.

What is interesting about this study is researchers also found that the tumors can regress or shrink in size after treatment with an insulin sensitizer, possibly leading to other ways to assist in the treatment of breast cancer in the future. This study was recently published online in Cancer Research.

Researchers from the University of Colorado Medical Campus in Aurora compared nutrient distribution in skinny and obese female rats with breast tumors before and after surgically removing the ovaries of the rats. This procedure basically induced menopause in the rats, causing them to gain weight.

The researchers found excess nutrients were deposited into breast tissue and peripheral tissues in the skinny rats, but into the tumors of obese animals. Yes, the obese rats took up more of the calories and nutrients directly into the breast tissue than the skinny rats.

Tumors from obese animals had increased progesterone receptor expression, which was associated with an increase in glucose (sugar) uptake, and subsequently growth of the cells.

When the rats were treated with metformin, a drug used in humans who have diabetes, the tumors shrank and progesterone receptor expression decreased. Breast tumors from postmenopausal women showed a similar correlation between progesterone receptor expression and these same metabolic changes.

This data seems to suggest that there is a window of menopausal weight gain that may provide a time during which insulin sensitizers such as the drugs we use to treat diabetes, and other interventions that improve metabolic control, could be highly effective for the treatment and prevention of postmenopausal breast cancer.

While this study is intriguing, the same study now must be carried out in humans to see if the regulation of weight gain and diabetes may play a role in the treatment of breast cancer.

Dr. C. Joseph Bennett is a board-certified radiation oncologist and a member of the Citrus County Unit of the American Cancer Society. Watch “Navigating Cancer” on WYKE TV at 7:30 p.m. Tuesdays and at 10 a.m. Thursdays. If you have any suggestions for topics, or have any questions, contact him at 522 N. Lecanto Highway, Lecanto, FL 34461, or email cjbennett@rboi.com. ­