New research suggests that prostate cancer patients with low risk or low PSA scores need not go for immediate treatment or surgery. The study says that surgery did not reduce the likelihood they would die from prostate cancer or other causes. But the findings indicate that surgery did reduce mortality in two groups of men – those with relatively high PSA levels (greater than 10 ng/mL) and potentially those with higher-risk, more aggressive tumours.
Gerald Andriole, the co-author of the study, says that data suggest that men with high PSA levels and those with more aggressive tumours likely benefit from early surgery, and these men should undergo treatment because their tumours are more likely to be lethal if left alone. During a study involving 731 men, surgery reduced prostate cancer deaths among men with PSA levels greater than 10 ng/mL, an indicator of larger, more aggressive tumours. Of these men, 5.6 per cent in the surgery group died, compared with 12.8 per cent of those in the observation group.
Fewer deaths from prostate cancer also occurred among men treated with surgery who had high-risk prostate cancer, classified as a PSA level above 20 ng/mL and a score of 8-10, a measure of tumour aggressiveness. In this subgroup, 9.1 per cent of men who had surgery died, compared with 17.5 per cent for observation. Throughout the study, deaths from prostate cancer occurred infrequently. Among men treated with surgery, 21 (5.8 per cent) died of prostate cancer or treatment, compared with 31 (8.4 per cent) in the observation group - a finding that is not statistically significant.
The study’s findings support the results of the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial, which to date has shown that most cancers detected by repeated PSA screening are low risk and that annual prostate cancer screening does not reduce mortality. Andriole is leading that study and is chairman of the PLCO’s prostate cancer committee.
“The findings of these two studies should be reassuring to men with low-risk prostate cancer,” says Andriole. “PSA screening commonly results in the discovery of cancers that are generally not a threat to life. This ‘over diagnosis’ of non-lethal cancers is concerning in and of itself and becomes especially problematic if men with such low-risk cancers are ‘over treated’ since they are unlikely to benefit from the treatment and may experience side effects like incontinence and impotence.”
The results of both the PLCO study and the current study, called Prostate cancer Intervention Versus Observation Trial (PIVOT), were among those considered by the US Preventative Services Task Force, which recently gave PSA screening a Grade D recommendation and generally discouraged its use.
Instead of treatment early on, Andriole says many men with low-risk prostate cancer detected by PSA screening initially can be managed with “active surveillance.” This involves periodic PSA tests and biopsies to monitor tumour growth.
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