A study of 25,000 women, 19,000 of whom received In-Vitro Fertilization (IVF) found that the women who underwent IVF had higher rates of ovarian cancer. The cases of ovarian cancer in women who had IVF were borderline tumors. The women who did not undergo IVF were also classified as “sub-fertile” lending evidence to the theory that the IVF, not the underlying cause of the infertility, raised the risk of this “non-fatal” type of ovarian cancer.
See a news article on the study here
The full study can be found here