@Rigel The usefulness of a procedure or test is a factor of many things, including 1. Cost 2. Accuracy (sensitivity - the ability to tell that a patient truly has a problem, measured by low false negatives, and specificity - the ability to tell that a patient truly does not have the problem, measured by low false positives) 3. Ease of test on the patient 4. Actual liklihood of the problem existing 5. Severity of actually having the problem.
Since the cost of physical exam is $0 (beyond the cost of the appointment) the exam should be done unless it would never yield information) The DRE does often help with diagnosis, but does have problems with both sensitivity and specificity. PSA is low cost, but suffers from sensitivity and specificity problems. Ultrasound is more expensive, invasive, and suffers from problems with both sensitivity and specificity. Cystoscopy is increasingly expensive and invasive, and doesn't do well at detecting Prostate cancer, but is great with Prostatic hypertrophy and causes of blood in the urine.
In your case as you've described it, if I was still practicing, I would have done the PE & DRE and noted the increased Prostate size without lumps. I then would have discussed the risks and benefits of PSA, but probably discouraged it. I would not have ordered Ultrasound or Cystoscopy. Now that you've had a PSA, it makes sense to follow it yearly, as serial testing increases the accuracy quite a bit. In the absence of rapid growth, increasing PSA's or other problems, the liklihood of dying of rather than with Prostate cancers is quite low.
Sensitivity refers to the test's ability to correctly identify individuals with the disease, while specificity refers to its ability to correctly identify individuals without the disease.