tate gland when diagnosed. Many of these are small tumors which will remain in the prostate gland for the entire life of the patient.
Prostate cancers are classed as low−risk or high−risk based on three factors: the size of the tumor, whether it is confined to the prostate gland and its microscopic appearance (the lowest risk tumors are not that different in appearance from normal prostate tissue; these are called well−differentiated tumors). The lowest risk tumors are small, well−differentiated tumors which are confined to the prostate gland.
The problem in selecting a treatment comes from the fact that a small number of these low−risk tumors will spread to other parts of the body fairly quickly and doctors are unable to tell which ones will do this. Whether the odds of this happening are one in fifty or one in a million, nobody wants to be the one. And treatment is usually selected as if the patient will be that one.
The PSA Screening Test
In 1987, a screening test for prostate stimulatory antigen (PSA) was introduced. A high PSA reading is not a diagnosis of prostate cancer; it is merely an indication that a person may have prostate cancer. Diagnosis of prostate cancer requires further testing, usually a biopsy. Since the advent of PSA screening, more cases of prostate cancer are being detected and these cancers are being found at an earlier stage; many would never have been found at all if the PSA test had not been given. And detection of prostate tumors that will never cause any symptoms is virtually useless information.
In the first study, published in the October 7 issue of the Journal of the National Cancer Institute, H. Gilbert Welch and Peter C. Albertsen found that since the introduction of PSA screening, 1.3 million men were diagnosed with and over one million treated for prostate cancers that would have gone undetected without PSA screening. The fact that these cancers would never have been diagnosed indicates that most of them caused no symptoms in their patients. This suggests that these cancers did not require treatment. The diagnosis of a disease in patients where that disease will never cause symptoms is called over−diagnosis.
The death rate due to prostate cancer has also fallen since the introduction of PSA screening. How much of this is due to the screening? The authors estimate that if the entire decrease in the death rate was due to PSA screening—which is highly unlikely—over 20 men were diagnosed with prostate cancer for every life saved. Since around 80% of those diagnosed sought treatment, roughly 15 of every 20 men whose prostate cancer was found because they were screened for PSA sought treatment needlessly.
The Risks for Men Over 65
The second study, published in the September 16 issue of the Journal of the American Medical Association, focused on elderly men. Grace L. Lu−Yao headed the study, which looked at the survival rate of men who elected not to treat their prostate cancer with radiation or surgery for at least six months in the post−PSA era and compared this to the rate in the pre−PSA era. The men in this study were all over 65 at the time of diagnosis; their average age was 78. The study found that men who elected this conservative treatment are doing much better now than they did in the past.
Liu−Yao suggests that this should cause physicians and their patients to reconsider conservative treatment, particularly in light of earlier studies suggesting little if any benefit from more aggressive treatment. Liu−Yao stresses that the information in her study applies only to those over 65 at the time of diagnosis; the results should not be applied to younger men.
In the third study, published in the August 31 issue of the Journal of Clinical Oncology, a team that included Martin G. Sanda sought to examine the consequences of choosing deferred treatment after a diagnosis of prostate cancer. The men in this study were an average age of 60 at the time of their cancer diagnosis. Using data on 51,529 men from the Health Professionals Follow−up Study (HPFS), the team found no statistical differe