"No such test exists...."

There have been quite a few genes identified that are considered markers for increased risk of cancers, especially breast cancer. Among them are BRCA1, BRCA2, ATM and a couple of fairly recent ones CHEK2 and BRIP1. Much work is ongoing in this area and new one's are always being discovered.

Insurance companies often surreptitiously test for these if there is a history of cancer in an applicant's family.