Seesawing Between Breast and Colon Cancers

Colon cancer risks higher in women with highest levels of microchimerism

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) When a woman has a baby, the cells of her unborn child circulate in her body for decades after childbirth. Likewise, some of her cells are in the body of her child for years, too. This is called microchimerism.

The circulating fetal cells have now been linked to cancer risks later in life.

Researchers now know that Y-chromosome (male) fetal cells are linked to later development of breast and colon cancer in mothers of children of either sex. Scientists don't understand the biology behind this, though.

Women with the lowest levels of these cells had a 70 percent lower risk of breast cancer as compared to healthy controls. But women with the highest levels were more than four times more likely to have colon cancer.

"Keep moving and eating healthy throughout your pregnancy."

Vijayakrishna K. (V.K.) Gadi, MD, PhD, an assistant member of the Clinical Research Division at Fred Hutchinson Cancer Research Center, was senior author of the study, led by researchers at the University of Copenhagen in Denmark.

The findings are based on data from blood samples drawn from 428 cancer-free Danish women in 1980s. A decade later, researchers combed through Danish breast and colon cancer registries to determine if the participants had developed cancer.

The molecular make-up of the blood samples was completed at the Hutchinson Center. This analysis measured the amount of microchimerism the women had. They found that the male fetal cells were detected in:

  • 40 percent of 89 women who developed breast cancer
  • 90 percent of the 67 women who had colon cancer
  • 70 percent of 272 women who were cancer free

Past studies had shown that microchimerism has a beneficial effect on breast cancer, but had never been measured in women with colon cancer.

"Fetal microchimerism may be highly relevant to later cancer development. However, the study does not allow us to identify the underlying biological mechanisms," Dr. Gadi said.

The researcher has a theory that the fetal cells are involved with and possibly even driving chronic inflammation in the gut, which could lead to colon cancer.

So what about women who never had baby boys? No matter. The study found that 65 percent of the women who never gave birth to a son have the Y-chromosome fetal cells.

Overall, 65 percent of women with no live-born sons tested positive for Y-chromosome fetal cells, according to the study.

This research was published online Mary 3, 2012 in the European Journal of Cancer.

The study was funded by the Danish Cancer Society.

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Review Date: 
May 7, 2012
Last Updated:
May 7, 2012