Neither that good. Neither of these examinations is particularly good at detecting prostate cancer. Both should be employed in a person at risk for prostate cancer.
Not really. Digital rectal exam (dre) is a part of the yearly exam for men and used in conjunction with psa for screening of prostate cancer. The prostate exam will only detect abnormalities that result in "nodules" or other surface variations of the prostate that can be felt on exam. In us, the majority of prostate cancer is not palpable (not detected with rectal exam) and only discovered with psa test.
PSA. Once a year. Or if there is a change or complaints during urination.