In 1998, one US hospital reported their experience with the herbal formula in a handful of patients who had refused conventional treatment. In every case, there was objective evidence of benefit in the form of significant declines in both testosterone and PSA levels (N Engl J Med, 1998; 339: 785-91).

This was followed by a survey of more than 100 prostate patients, 77 per cent of whom said they had found PC-Spes to be beneficial. They also showed huge declines in PSA levels, taken as a sign of cancer regression. No clinically significant adverse effects were seen (Mol Urol, 1999; 3: 333-6).

Also, a team at the Oncology Division of New York Medical College published the results of a study of rats injected with 'aggressive' human prostate cancer cells. Conventional treatments are generally not successful in such animals, but PC-Spes produced an overall 50 per cent reduction in cancer and, in a third of the rats, the cancer completely disappeared. No side-effects were seen. It’s wise to remember, of course, that animal studies may not apply to humans (Int J Oncol, 1999; 14: 713-9).

Another hospital trial followed in 2000, involving 14 seriously ill men for whom chemical and actual castration had failed. Doctors found that 3 g/day of PC-Spes significantly improved their quality of life and reduced the pain of the disease. Again, there were no side-effects (BJU Int, 2000; 85: 481-5).

Later that year, doctors at the University of California Medical Center in San Francisco gave PC-Spes to 70 progressive prostate cancer patients, some of whom were not responding to conventional treatment. Again, the results were positive. Most of them showed reduced PSA and testosterone levels, and a few even achieved a regression of the cancer. In this study, some side-effects were recorded - mostly breast tenderness and diarrhoea, plus a few cases of allergic reactions and deep-vein thrombosis - which were all considered to be 'acceptable' (Clin Oncol, 2000; 18: 3595-603).

Another hospital study - from Boston’s Dana-Farber Cancer Institute, linked to Harvard - found similar results to the earlier studies. They concluded that 'PC-Spes is a well-tolerated and active treatment for prostate cancer' (Urology, 2001; 57: 122-6).

To date, there have been over a hundred published studies on PC-Spes, almost all confirming its benefits. Nevertheless, last February, PC-Spes was suddenly withdrawn from sale.

The official state laboratory of the California Health Department had tested a sample of PC-Spes and claimed to have found 'undeclared prescription drug ingredients that could cause serious health effects if not taken under medical supervision'. The drugs were warfarin (an anticoagulant) and alprazolam (a benzodiazepine), which are available only on prescription and sold under the names Coumadin and Xanax, respectively. This investigation came on the heels of reports that traces of the synthetic oestrogen diethylstilboestrol (DES) had been detected in some batches of the herbal formula.

What seems most puzzling is why these compounds had evidently not been discovered before in any of the earlier PC-Spes studies. However, an official question mark had been raised about PC-Spes, and the US authorities lost no time in banning it.

The manufacturer of PC-Spes, a California company called BotanicLabs, strongly deny that their product was knowingly contaminated, saying that the chemical signatures of natural herbal compounds may mimic prescription drugs. Some observers also suspect dirty tricks. 'We don’t have complete control of the supply chain,' said BotanicLabs in May.