Son's Cells Linked To Mother's Cancer

Take a look at your mother and you see a bit of yourself in her. Thing is you really are seeing a bit of yourself in her because she is home to some of your cells. They have been living as part of her ecosystem ever since the day you were born when a few of your fetal cells opted to stay behind, perhaps preferring mum's comfort. Depending on how you turned up since then, those cells may have made the right choice. For your mum though, your fetal cells present with a mixed bag of effects-cancer-related effects.

Until now, scientists did not know that the presence of fetal cells was linked to risks of cancer in the mother. But a new study published in the European Journal of Cancer indicates that the presence of Y-chromosome (or male) fetal cells may well play some role. The news is a mixture of good and bad: it is possible that the presence of Y-chromosome fetal cells may have a protective role against breast cancer but an enhancing role for colon cancer.

The study looked at a group of 400+ healthy cancer-free Danish women, sampled in the 1990s. Back then, the scientists collected and analysed blood from the women for Y-chromosome fetal cells. Why no analysis of female fetal cells? Because it is currently a pain to distinguish between female fetal cells and the mother's female cells. The scientists do stress that the potential effect of female fetal cells should not affect the effects of Y-chromosome fetal cells however.

The 428 Danish women sampled were followed for incident cancers until 2006. Of them, 89 had breast cancer and 67 had colon cancer, with the remaining being cancer-free. Crucially, of the 89 women with breast cancer, 40% had Y-chromosome fetal cells while 90% of the colon cancer-inflicted women had Y-chromosome fetal cells. In less mathematical terms, those figures roughly translate to this: women who have Y-chromosome fetal cells were three times less likely to have breast cancer but four times more likely to have colon cancer.

The study clearly indicates that there exists a link between presence of Y-chromosome fetal cells and breast and colon cancer incidences in the mother. However, since the study does not determine an actual causal pathway as to how the fetal cells may prevent breast cancer and enhance colon cancer, there is still the possibility that the fetal cells do not actually play any role in the cancer incidences at all. Presence of the fetal cells may merely reflect the real underlying cause of cancer.

The apparent contradictory role of fetal cells in the mother was not the only surprise that the study spilled. You may think that the more sons the mother has, the more fetal cells have accumulated in her body. Wrong. Turns out that the number of Y-chromosome fetal cells present in the mother does not depend on the number of sons she gave birth to. However, the absence of association may be because Y-chromosome fetal cells are present even in some women (65%) who never gave birth to boys. Those Y-chromosome fetal cells, the scientists speculate, may well be the remnants of terminated male pregnancies.

Now call your mum and tell her that you are always with her. She'll be happy. But better not mention the C-word.

Image credit: Lunar Caustic (on flickr).

Reference: Kamper-Jørgensen, M., Biggar, R.J., Tjønneland, A., Hjalgrim, H., Kroman, N., Rostgaard, K., Stamper, C.L., Olsen, A., Andersen, A.N. & Gadi, V.K. (2012) Opposite effects of microchimerism on breast and colon cancer. European Journal of Cancer, DOI: 10.1016/j.ejca.2012.02.006