The prostate gland is a walnut-sized gland located beneath the perineum, the stretch of tissue between the scrotum and anus in men. It surrounds the urethra, the tube that carries urine from the bladder through the penis, at its exit from the bladder. The prostates’ function is to add fluid volume and certain nutrients to semen, and many men can feel it contract during orgasm and ejaculation. Non-cancerous enlargement of the gland is quite common and can cause problems in urination since it can press upon the urethra. A previous article of mine discussed this condition, called benign prostatic hypertrophy (BPH).
No one knows why this small gland accounts for more cancer than much larger organs. There is certainly evidence of genetic susceptibility since men whose fathers or brothers have had the disease are at higher risk. It may also be that the BRCA genes, which have been shown to increase the risk of breast cancer and ovarian cancer in women, may play a similar role in prostate cancer.
After lung cancer, prostate cancer is the most common and deadly cancer to affect men. One out of six men will be diagnosed, and it is the ultimate cause of death in about one man in thirty-four. According to the American Cancer Society, we are now seeing about 232,000 new cases of prostate cancer every year, with about 30,350 annual deaths. Traditionally cancer affecting men over the age of 65, more cases have been seen in recent years in younger men, especially among African-Americans, who suffer from a higher incidence than other groups. Asian men have a lower incidence than men of European descent.
The causes of this declining age when prostate cancer is first diagnosed are not clear. Certainly, the now widespread practice of testing with the PSA test (prostate-specific antigen), has made earlier, and therefore younger diagnosis more frequent. Whether this has resulted in more cures, or a lower death rate remains quite controversial, and I shall discuss this further below. Advances in the treatment of other potentially fatal diseases, such as coronary artery (heart) disease, are also thought to allow more men to live long enough to come down with prostate cancer.
When caught early, before it has spread away from the gland or metastasized, the cancer is often curable. Surgery, external radiation or the implantation of radioactive seeds, HIFU (high intensity focused ultrasound) and cryotherapy (freezing) are all being used, alone or in combination. However, if cancer has spread through the cover of the gland to involve surrounding tissues, or to the lymph nodes or further, then the treatment options are much more limited. This cancer is not very sensitive to the forms of chemotherapy which we presently use. Since the cancer is often dependent on the male sex hormone, testosterone, for its growth, removing all the testosterone from a man’s body, either by surgically removing the testes, or by giving injections of a pituitary hormone which essentially shuts down the production of testosterone will often provide a temporary slowing of the growth of cancer, and will sometimes dramatically relieve the bone pain which is so typical of this cancer. Unfortunately, as with most types of hormonal therapy or chemotherapy, the cancer cells tend to become resistant and therefore unresponsive to the therapy, and cancer then grows without restraint.
When considering the usefulness of the PSA test, I want to point out some aspects of this cancer that make the evaluation of any early screening test problematic. Although we commonly think of prostate cancer as very deadly, in fact, the vast majority of men will develop it at some point in their lives, and will not die of it, or even be diagnosed. Autopsies of men dying at age 80 of other causes have shown that approximately 80% have prostate cancer, never diagnosed when they were alive, which would probably have never become clinically apparent even if they had lived longer. Studies of younger men have shown lower, but still high rates of hidden prostate cancer. The problem with the PSA test is that it may be detecting many of these hidden cases which would never have become clinically apparent, and would never have killed the men harboring them.
If removing these small and perhaps non-harmful tumors were easy, then we could go ahead and take them all out without worrying about the consequences. Unfortunately, all of the current treatments do have serious complications, including impotence, incontinence, and in the case of the radiation therapies, damage to the rectum. Obviously, removing a cancer which would never have affected a man, and thereby making him impotent or incontinent is not something we wish to do. So the important question is, by treating all the early cancers detected by the PSA test, are we really curing people who otherwise would have died of the cancer? Even experts are divided on this question, and the studies necessary to determine the answer are still being done. Since waiting to see if subjects die of a disease takes many years, these studies will not be providing answers very soon.
Determining which forms of treatment provide the highest likelihood of cure can also be difficult. Many experts consider a man cured only if his PSA level falls to less than 0.2 ng/ml, that is, essentially to zero, and does not rise for 10 years. Some newer types of therapy have simply not been around long enough to be evaluated by this standard.
So you might ask, well Doc, youre a man, what are you doing about getting screened for prostate cancer? I have had a PSA test once, done without my doctor asking if I wanted it, and it was normal. But now that I have reached the age of 70, I am determined not to have the test done any more. That may sound crazy, since the older a man gets, the more likely he is to have this cancer. But it is also true that the older a man gets, the more likely he is to die of something else: that is to die with prostate cancer, but not from it. So if I had a positive test, I would be on the slippery slope of having prostate biopsies to determine if cancer is present, since not all positive PSA tests are caused by cancer. Then if the biopsy were positive, I would have to decide about treatment, and run the risk of the complications I mentioned above. Since the vast majority of cancers in men over 70 do not kill them, and indeed do not even make them sick, I would prefer to opt for no testing, and no treatment. Growing older is hard enough without having to worry about impotence or incontinence.
For a man at high risk, testing with the PSA test starting around age 45 may make sense. But for most men, I think waiting, either for better tests or for better treatments, is sensible. In my practice, if a man requests a PSA test, I try to present the arguments pro and con the test and will order it if he still wishes, but I don’t do the test automatically.