Prostate cancer misdiagnosed in some men

Overweight men are far more likely to get misleading results to prostate cancer tests that compromise their treatment, new research has revealed.

A study has found that prostate biopsies commonly used to diagnose the extent of the disease regularly underestimate the severity in men carrying extra weight.

The results, published by US scientists on Wednesday, suggest that many men receive inadequate or inappropriate treatment that is not aggressive enough to combat the true nature of their disease.

Cancer Council Australia chief executive, professor Ian Olver, said the findings were concerning, and urged clinicians to carry out more thorough testing on these patients.

The study compared biopsy results with actual disease in more than 1,100 US men who had had their prostate removed as part of their cancer treatment.

A biopsy - surgery to remove and test small slices of the organ - typically follows the standard PSA blood test used to indicate the presence of disease.

The research, led by Duke University, showed that obese men were 89 per cent more likely than slim men to have a more aggressive form of prostate cancer than was indicated by biopsy.

Men who registered as overweight but not obese had a 44 per cent increased risk.

Study leader Stephen Freedland said the results were worrying because under-diagnosed men potentially miss out on additional treatment, like hormone therapy, that could save lives.

It was already known that PSA test readings were less accurate in overweight men, he said.

"These findings further suggest that we could be missing even more high-grade disease among obese men," Dr Freeland wrote in the latest issue of the journal Urology.

The reason for the discrepancy was still unclear. But the researchers believe obese men's larger prostates could mean that the usual number of samples taken during a biopsy is insufficient to reveal the gland's actual status.

Prof Olver said it was important clinicians were aware of the problem and conducted more biopsies on these patients to get a more accurate result.

"It also underlines the fact that we need better ways to diagnose and predict the outcome for this disease," Prof Olver said.