Recently, we reported microchimerism to be oppositely associated with maternal breast and colon cancer. In women with a blood test positive for male microchimerism the risk of breast cancer development was reduced to one third, whereas the risk of colon cancer was elevated 4-fold. In this article addendum, I report the survival of cases in the original study after being diagnosed with cancer. Despite small numbers, the analysis suggests that microchimerism may be positively associated with survival after breast and maybe colon cancer diagnosis. Despite the findings on colon cancer in our original report, I speculate whether microchimerism could have a general beneficial role in cancer, which in some sites may not be evident because an allogeneic maternal immune reaction hastens cancer development.