I have done a lot of research. You have an increased risk (<10percent) of being diagnosised when a first generation relative (mother or sister) have cancer, usually Breast, Ovarian or Colon. There is also genetic testing that can be done, if someone is positive for BRCA 1 or BRCA 2 they have an increased risk of 40 percent, many of these women will have profolatic surgeries when their child bearing is done.
MOST ovarian cancers are sporadic but, I do not know how a doctor can make that determination with doing genetic testing when there is a strong history in the family.
My Moms ovca is also sporadic BUT we did the genetic testing. No doctor can tell you weather its sporadic or not unless they do a genetic test. You should absolutely have your Mom do a genetic test and if there is a mutation in either BRCA1 or BRCA2 then you should follow that test as well to see if you carry the mutation. We all carry those genes the importancy is weather we have a mutation or a defected gene that is unable to fight off those cancer cells that everyone produces on every day basis.
Take care
Leslee had the BRAC testing done and it came back negative, so they told her that she had a 1% chance of getting OVCA, no family cancer factor, none of the other risk factors , so they have told her it might be a gene they haven't found yet or environmental. The only good out of all this testing is that her 3 daughters are not at a high risk. The test took 7 weeks for a return and cost over $3,000. Her insurance covered it. They also told her that they are close to isolating the protein that has been found to be present in 80% of dx OVCA women. She had this test done because her father was present at the Atomic testing done in 1946 in the Pacific. 69% of those men developed cancer and the government is following the offspring of those men, her DNA was entered into that data base.