From the NY Times: Symptoms Found For Early Check on Ovary Cancer. The symptoms are:

Bloating
Pelvic or abdominal pain
Difficulty eating or feeling full quickly
Feeling a frequent or urgent need to urinate

According to the article:

A woman who has any of those problems nearly every day for more than two or three weeks is advised to see a gynecologist, especially if the symptoms are new and quite different from her usual state of health.