It's pretty well known that "ovulation inducing" drugs like Clomid are highly suspected of causing ovarian cancer. The ovary is by nature a cyst/tumor producing organ, therefore the more tumors, the higher the chances of something going awry. Ovarian cancer is the 6th most frequent type of malignancy occurring in women.
Here is what IVF.com had to say about Clomid (and, one must assume they're putting the best spin on it possible) : "It is not a natural compound, and is a relative of tamoxifen and DES." Ugh--remember what a mess DES was? (It was the drug that supposedly would help prevent miscarriage, so they gave it willy nilly to pregnant women from 1937-1971 (eeeek!)--it was proven ineffective AND produced a generation of " DES daughters" [ugh, note the happy faces the CDC puts on this] with deformed or missing uterii, cancer, etc.)
They go on to talk about the "theoretical possibility" that any medication that would increase ovarian activity could result in an increased risk of ovarian cancer. Oops, but # 2 and # 3 kinda bring it out of the "theoretical":
* Isolated case reports of individual women who have taken ovulation inducing medications and were found to have developed ovarian cancer.
* Retrospective case controlled studies...noted that more of these women [with ovarian cancer]had taken “fertility medications” than would have been expected when compared to a “control group” of women who had not taken these medications.
In my previous incarnation as the Fertility columnist for Adoption.com, I heard from a LOT of women whose docs (sometimes just their primary care physicians) would put them on Clomid for no real reason, just because they'd been trying to get pregnant for over six months or something, and many of them reported awful (and sometimes lasting) side effects (migraines, a big one) AND continued infertility.
But (fair and balanced?) I do know someone who was put on Clomid, stopped it because it made her crazy, and then went on to conceive naturally--twice. She believes the Clomid kickstarted her repro system. The Don't-piss-off-Mother-Nature in me focuses on the fact she conceived once she STOPPED the Clomid.
FertilityBitch's suggestion? Drink organic black tea (in a non-dioxin-y bag, please) if you are or have taken Clomid (hello, Barry Bonds?). Two cups a day'll reduce your risk almost FIFTY percent according to the study. And drink black tea anyways--never can have to many anti-oxidants in today's polluted world.