"Fetal Cell Transplant” Could be Link Between Reduced Risk of Breast Cancer and Motherhood

Some benefits of motherhood are elusive, but one has been validated through biostatistical studies: women who bear children have a reduced risk of developing breast cancer.

In Seattle (WA, USA), researchers at the University of Washington and Fred Hutchinson Cancer Research Center believe they have identified a source of this protective effect: fetal cells "transplanted” to the mother before birth. Their findings were described in the October 1, 2007, issue of the journal Cancer Research.

The ability of cells from a growing fetus to take up long-term residence within its mother is a process called fetal microchimerism. According to the investigators, while fetal microchimerism has been implicated as a mechanism of autoimmune disease, it may also benefit mothers by putting the immune system on watch for malignant cells to destroy.

To test the hypothesis, the researchers recruited 82 women, 35 of whom had been diagnosed with breast cancer. About two-thirds of the women evaluated have had children, and more than 50% of the participants had given birth to at least one son. The researchers took blood samples from each participant and searched them for male DNA, as they believed it is a comparatively definitive matter to detect the male Y chromosome amid the mother's native--and distinctly female--cells within a blood sample.

Among the women with breast cancer, only five had male DNA in their bloodstream. Three of the five previously gave birth to sons, one had had an abortion, and the other had never been knowingly pregnant. In total, approximately 14% of all women in the breast cancer group had male DNA in their bloodstream compared to 43% of women in the non-breast cancer group.

"Our research found that these persisting fetal cells may be giving a woman an edge against developing breast cancer,” said lead author Vijayakrishna K. Gadi, M.D., Ph.D., assistant professor at the University of Washington and research associate at the Fred Hutchinson Cancer Research Center. "This experiment of nature is all the more fascinating because for years doctors treated a number of different cancers by transplanting cells from one person to another.”

According to Dr. Gadi, these results could provide a starting point for future research on the role of fetal microchimerism in the prevention of cancer. Moreover, there are other reasons for male DNA to be in a woman's peripheral blood, such as miscarriage and abortion, or perhaps even blood transfusion or a male twin that was reabsorbed into the womb at an early stage of the pregnancy.


Related Links:
University of Washington
Fred Hutchinson Cancer Research Center