Ironically, fertility enhancing treatments also seem to have the same effect on cancer, by increasing the risk of cancer in women who undergo fertility treatment.

Treatment for infertility almost always involves intake of fertility drugs, but it appears by improving fertility and the chances of a woman to conceive, the fertility drugs may simultaneously be increasing the risk of cancer. The risk of uterine cancer in particular is seen to increase.
Ovulation-inducing drugs are common in treatment of infertility. The effects of these drugs on the health of the women who use them have not been verified yet.

The studies conducted on the topic come out with contradictory findings on the direct relationship between medication intake and ovarian or breast Cancer. Certain constraints on the research such as the short duration of study or inclusion of women with a higher propensity for cancer due to other reasons are cited as reasons for lack of absolute clarity in the findings.

A recently conducted study on 15,000 Israeli women 30 years after they gave birth was published in the American Journal of Epidemiology. Out of this large group, 567 had used ovulation-inducing drugs. 362 women also took the fertility drug clomiphene. The study revealed that the subjects developed cancer at a higher rate than the other drug-free women; they were also at a higher risk for developing other forms of cancer.

A study conducted at the Stanford University also says that the correlation between ovarian cancer and fertility drugs was more predominant in those women who took fertility drugs, but never became pregnant. This could suggest the cancer risk to be associated with the type of infertility rather than the treatment drug use itself.

Besides breast cancer, increased risk of developing other forms of cancer, like skin cancer and non-Hodgkin's lymphoma were also noted. Still, in spite of the large sample used in the study, scientists say it is not easy to draw reliable conclusions because a detailed history of fertility drug use for all the women were not available. Also, only a very small percentage of women developed uterine cancer.

The findings are nonetheless significant. Medication that blocks the brain's estrogen receptors are found to increase the risk of uterine cancer.