Nevertheless, the current recommendation is that although vasectomies should still be performed, patients should be given informed consent about a possible link with prostate cancer.

At the moment, screening for prostate cancer is just a simple matter of a blood test and a rectal check to see whether it's likely that a cancer is developing. But the Prostatic Specific Antigen (PSA) blood test has attracted much criticism (JAMA 1992; 267: 2236-8). It's feared such tests can't accurately establish whether patients thought to be free from prostate cancer actually have it (JAMA, December 9, 1992) because so much has still to be learned about the way that prostate cancer behaves.

There is also a fear that nationwide screening to include PSA tests could lead to over-treatment of large numbers of men with drugs, surgery, or radiotherapy unnecessarily, when monitoring the patient and improving the diet would be a far more effective course of action to take. It would also cost a fortune, running at many times the cost of today's treatment (Urol Clin North Am, 1990; 17: 719-735).

Screening programmes carried out in America show that an annual examination alone may be insufficiently frequent and/or sensitive to prevent deaths from prostate cancer and therefore contradicts the conventional wisdom that early detection and treatment of cancer saves lives (JAMA 1993; 269: 61-64). It doesn't.

One can draw parallels here with the thinking on breast cancer, where 20 years ago it was assumed that visits to breast screening clinics where breast cancer could be spotted earlier would therefore lead to its effective treatment. It hasn't (JAMA, September 15, 1993). However, the rationale behind prostate cancer screening is not based on a series of controlled trials which show it actually works, but on a subjective sense that it ought to help. No treatment at any stage of the disease has been shown to improve survival in an adequate clinical trial (BMJ, March 27, 1993).

Research conducted earlier in the year by the Harvard Medical School and the Harvard School of Public Health concludes that we shouldn't write off PSA screening entirely since further tests into its costs and clinical effectiveness could well improve the way we spot prostate cancer in its early stages of development (JAMA, January 25, 1995, February 15, 1995 and September 14, 1994).

The National Cancer Institute has also launched a major examination of such tests the prostate, lung, colon rectum, and ovary cancer screening trial. This will evaluate the screening tests for these four diseases and plans to report before the end of the century (Ann of Int Med 1993; 119: 914-923).

However, there are reasons to be concerned about whether a clear answer will be forthcoming, even if the study is completed. Mostly for practical reasons, the study includes men aged between 60 and 74. So, regardless of the examination's outcome, the impact of screening on men younger than 60 will not be known (JAMA , June 1, 1994).

This is really bad news when other trials suggest that screening for prostate cancer should be confined to high-risk, young men who ought to have the greatest chance to benefit from early detection (The Lancet, 1994; 344: 1594-98 and BMJ, 1995; 310: 1139-40).

Transrectal ultrasound (TRUS) and magnetic resonance imaging are also being used to spot and monitor potential cancers. However, the technology has been shown to be inaccurate where prostate cancer is concerned, not indicating clearly whether or not the cancer is malignant (JAMA, August 17, 1994).