PSA Screening Results in 30 Percent Over-Diagnosis
24 Apr 2003
For women, a telephone call reporting that mammography has detected an abnormality, and a second picture is needed, triggers instant fear of breast cancer. For men, an elevated PSA (Prostate-Specific Antigen) test has the same devastating effect. They dread the thought that they’ve developed cancer of the prostate gland with all its grim implications. But how accurate is the PSA test? And if a malignancy is present, what is the best treatment?
A report in the Journal of the National Cancer Institute is hardly reassuring about the accuracy of the PSA test. Researchers studied men ages 60 to 84 between 1988 and 1998. They estimated the PSA test over-diagnosed prostate cancer 29 percent of the time in white men and an amazing 44 percent in black males.
For years doctors and government agencies have questioned the merits of the PSA test. Some provinces claim that using the PSA test is too inaccurate to be useful as a screening procedure. But two high profile politicians, Allan Rock and Preston Manning say the early detection of prostate cancer by the test saved their lives. So whom do you believe?
Dr. Jim Paupst, Rock’s doctor, stresses "it’s the jump" which is vital to early diagnosis. He tracks the value of PSA annually and if a patient shows a 30 percent increase over the preceding year this starts a search for the presence of early malignancy.
Dr. Grant Farrow, a former professor of urology at the University of Toronto, says PSA tests are invaluable when there’s a family history of prostate cancer. But he also warns physicians to be aware of over-treating this malignancy.
Epidemiologists, on the other hand, say there is no proof that PSA screening saves lives. That one in three men in their 40’s have microscopic traces of cancer in their prostate gland, but only 4 percent will die from the disease!
Several years ago one of the world authorities on prostate cancer issued the same caution. He reminded us that "growing older is invariably fatal, cancer of the prostate only sometimes".
We know that at 70 years of age 50 percent of males show microscopic evidence of malignancy of the prostate. But it’s such a slow growing cancer that these men usually die of something else many years later.
So what should men do if a biopsy comes back positive for prostate cancer? It’s been said that wars are too important to be left to generals. One could say with equal passion that treatment decisions about prostate cancer are too important to be left entirely to doctors. Currently, there is such a diversity of opinion about the best treatment that it’s imperative for patients to become well informed of the various options.
I believe one of the most sensible approaches is that used by The Massachusetts General Hospital in Boston. Men are given appointments to see a urological surgeon, a radiation specialist and sometimes a cancer expert. And all the pros and cons of these treatments are provided at that time.
For men in their 50’s surgery is often recommended particularly if the tumour appears to be aggressive and localized to the prostate gland. In other cases using medication to decrease the amount of testosterone followed by radiation is another possibility.
Some physicians believe, and I share this opinion, that for men in their70’s and 80’s "watchful waiting" is the best option. The belief that it’s better to live with the devil you know than the devil you don’t know. It’s one thing to be impotent after surgery or radiation. It’s another, if you have to spend the rest of your life in diapers.
Hopefully there will be a more accurate test for prostate malignancy in the future. But in the meantime the PSA test, a rectal examination and ultrasound are the only ways to detect this malignancy.
Unfortunately, some men will have many restless nights if the PSA test is reported abnormal. On the other hand, we know that three out of four men with an elevated PSA do not have cancer. The final diagnosis may be enlargement, infection or inflammation of the prostate gland. But this doesn’t remove the panic when the doctor calls.
