Ovarian cancer is one of the deadliest cancers known to womankind.  It's development is slow & insidious w/o any good means of screening with adequate sensitivity & specificity (statistical terms used to determine if any given test is good at picking out a condition and correctly ignores those w/o said condition).  As a result, most cases of ovarian cancer are found late in its course, unlike w/breast cancer for which modern mammography is able to detect minute microfoci of calcifications long before they metastasize (of course, this raises other issues which we'll gloss over today).  But as a result of this confluence of factors, we don't have anything (effective yet safe) to throw at it.