I know people didn't come here to read or think about cancer, but unfortunately it's something that many people have to deal with.
The field of Genetic Counselling started with cancer testing/counselling, because professionals knew it ran in families. Most cases are not due to genetic mutations, but due to environmental causes. Talking to a genetic counsellor can help you understand your risk, if a genetic test is recommended, if other family members should be tested, etc.
Cancer and genetics are very complex, and it's important to have a multidisciplinary team working with you. I hope I can help you in your first steps.