Testosterone linked to colon cancer in rats

"By showing that removing testosterone from rats leads to a drastic decrease in colon cancer susceptibility, it appears that male hormones may actually contribute to colon tumor growth rather than female hormones being protective," says James Amos-Landgraf. (Credit: Peter Kemmer/Flickr)

Testosterone may be a contributing factor in the formation of colon cancer tumors, new research with rats suggests.

Previous cancer research has shown that women are less likely than men to suffer from non-sex specific cancers such as cancer of the colon, pancreas, and stomach and scientists had theorized that perhaps this was due to a protecting effect created by female hormones, such as estrogen, that help prevent tumors from forming.

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In the new study, published in the Proceedings of the National Academy of Sciences, scientists observed normal levels of naturally occurring colon cancer in a group of male rats. When their testosterone was removed, colon cancer rates decreased dramatically. After reintroducing testosterone, the colon cancer rates returned to normal.

“By showing that removing testosterone from rats leads to a drastic decrease in colon cancer susceptibility, it appears that male hormones may actually contribute to colon tumor growth rather than female hormones being protective,” says James Amos-Landgraf, assistant professor of veterinary pathobiology at University of Missouri.

Post-menopausal women

Amos-Landgraf also points to higher rates of colon cancer in post-menopausal women as potential evidence to support testosterone as a contributing agent to tumor growth.

“All women have some level of testosterone in their bodies naturally, but those levels typically are much lower than estrogen and other female hormones,” he says.

“Once women experience menopause and their female hormone levels decrease, their testosterone levels become relatively higher. This corresponds to the time when they begin to experience higher rates of colon cancer and could be a sign of a relationship between testosterone levels and colon tumor growth.”

Amos-Landgraf plans to continue his research by investigating the genetic traits that are responsible for the difference in susceptibility to cancer between men and women.

The National Institutes of Health, the American Cancer Society, and University of Missouri funded the study.

Source: University of Missouri