Men who have had vasectomies are at greater risk of developing prostate cancer, according to two US studies of more than 73,000 men (The Lancet, 20 February 1993).
The researchers found that the likelihood of prostate cancer increased with the length of time since the operation. They speculate that the cancer may be triggered by the reduction in the secretion of prostatic fluid that follows vasectomy, or that the immune system may be compromised by the operation and, therefore, less able to ward off cancer.
One in 11 men in the US develops prostate cancer an incidence rate 50 times higher than in developing countries, according to a statement from the World Health Organization Human Reproduction Programme. Both the American Cancer Society and the American Urological Association recommend annual prostate cancer screening for men over 50, even though there is no evidence that screening improves individual prognosis.
According to Fritz Schroder, chairman of the department of urology at Erasmus Hospital, Rotterdam (The Lancet, 13 February 1993), screening simply leads to over treatment of cancers which pose no threat to life. Autopsy studies show that in the European Community, 32.9 per cent of men have prostate cancer, yet only 1.2 per cent will die from it.
"Thus if all cancers discovered at necropsy were identified clinically and treated, then 26 out of 27 patients would be treated unnecessarily because these tumours do not represent a threat to their lives," writes Schroder. Furthermore, the inaccuracy of the available screening methods (digital rectal examination, prostate specific antigen and transrectal ultrasonography) is so low that their use will "result in many unnecessarily worried men and unwarranted prostate biopsies," he warns.
Schroder adds that, as yet, there is no evidence that treating prostate cancer makes any difference anyway.
Another urologist, Robert Shearer, consultant at London's Royal Marsden Hospital, is about to seek approval from the Medical Research Council for a 15 year study to determine which treatment, if any, improves survival. "Many patients are impotent [after surgery for prostate cancer], and that's a high price to pay if you are not going to improve survival," Shearer says.