SEATTLE—For the first time, scientists have found what could be a causative link between the concentration of circulating Y-chromosome fetal cells in women who gave birth to children of either sex and their risk of later developing breast cancer and colon cancer. The findings show that the presence of fetal cells is a double-edged sword: Women with the lowest concentration of fetal cells were 70 percent less likely to have breast cancer, while women with the highest concentration of fetal cells had a four-fold increased risk for colon cancer when compared with healthy controls.
The how and why of this contradictory role of fetal microchimerism is not known and requires more study, according to Vijayakrishna K. (V.K.) Gadi, MD, PhD, an assistant member of the Clinical Research Division at Fred Hutchinson Cancer Research Center and senior author of a study that appears online in the European Journal of Cancer.
Scientists at the University of Copenhagen, Denmark, led the research, which was based on data from 428 Danish women whose blood was drawn in the mid-1990s when they were cancer free. Ten years later, the cancer status of these women was determined based on an examination of Danish breast and colon cancer registries. Molecular analysis of the blood samples was done at the Hutchinson Center to measure how much microchimerism they had. Male fetal microchimerism was detected in 40 percent of 89 women who had developed breast cancer, and 90 percent of the 67 women who had developed colon cancer. Residual male fetal cells were also found in 70 percent of the 272 women who remained cancer free.