The patron saint for cancer in general is St. Peregrine. (There are a few others, but Peregrine is the most well-known.) Most specific forms of cancer, female or otherwise, don’t have their own patron saint (one notable exception is St. Agatha for breast cancer). That said, if you know of someone dealing with cancer, there’s no reason why you couldn’t ask for Mary’s intercession. A woman I know who had uterine cancer found great comfort in asking Mary for her prayers and intercession. Patron saints are usually chosen because they have some biographical connection to the subject at hand, but Catholics believe that all people in heaven will pray for us if we ask.