I'm worried i have hnpcc. grandmother: colon cancer age 66 (survived, died of heart disease age 76), father: adenomatous polyp(s) age 46, now age 64 but had a few more polyps on later colonoscopies, grandmother's brother stomach cancer age 75 (survived, i think died of alzheimer's age 86). great-grandmother died of stomach cancer age 45-50, was not histologically confirmed. grandmother's other 4 brothers no cancer, one died of kidney failure in his 60s the other 3 are in their 70s, no cancer. i am a med student. i know cancer (stomach and colon) tends to set in in the 60s-70s in general population, but i'm worried b/c there is a clustering of GI cancers (and great grandmother died in her 40s)