The important part of this entire thread is that if you have symptoms, don't let the bell curve affect whether you seek treatment/exams from medical professionals. Colorectal cancer is no longer a rare thing in people under 50, and many practitioners operate under the naive idea that it doesn't occur in younger people.
The most important part of your sentence is "lifetime". Prostate is 11%, but most people don't get prostate cancer in their 30s.