Some cancer screening (such as for prostate) is generally done through blood test. Colorectal cancer screening has the "benefit" of the doctor being able to get

Some cancer screening (such as for prostate) is generally done through blood test. Colorectal cancer screening has the "benefit" of the doctor being able to get a front-row-center view. And some are detected by mri or even straight-up x-ray. There all quite different, as is the expertise needed for diagnosis.