The colon cancer finding was unexpected; no prior studies had ever associated that cancer with fetal microchimerism, Gadi said. The researchers chose to measure microchimerism in women who later developed colon cancer to determine whether the possible beneficial effect of microchimerism is specific to breast cancer, as past studies have shown.
Previous studies, including research by Gadi and colleagues, found associative links between concentrations of fetal microchimerism and a decreased risk of breast cancer as well as a heightened risk of some autoimmune diseases. However, those studies were based on blood drawn from women after the onset of their disease.
“Fetal microchimerism may be highly relevant to later cancer development. However, the study does not allow us to identify the underlying biological mechanisms," Gadi said.
Gadi has a hypothesis (not contained in the study) that the fetal cells could be producing a naturally occurring graft-versus-tumor effect but the effect may be having different impacts based on the cancer type. “There are diseases of the GI tract that are associated with chronic inflammation and it is entirely possible that fetal cells are driving, seeding or initiating that inflammation or are involved in the process," he said regarding the link to colon cancer.