Why colon cancer screening at 50 and not earlier?

Question

Can anyone point to the data which supports that screening should start at age 50? I don't understand why not 40 or 30 say. Curious numerically how they came up with that.

Answer 1

This article states that 90% of people who develop colon cancer are over age 50.

http://www.mayoclinic.org/news2000-rst/667.html

This one says that "Age 50 was determined as the starting age for screenings because that is the age that the risk for colon cancer begins to increase substantially. People with a history of colon cancer in their family should come in for a screening at age 40 rather than 50."

http://www.medicalmoment.org/_content/risks/mar04/210268.asp

Answer 2

Nobody tossed a coin and decided it is 50yrs,... most people get the disease then. But this norm isnt for all

People with hereditary polyposis have to start screening in tens.

People whose family memebers have had colon cancer have to screened starting 10 years bfore the age the others got it