Study reignites PSA screening debate

Debate over the value of PSA screening has been reignited, with a large study suggesting the practice has led to huge numbers of men being treated for prostate cancers that would never have progressed. The introduction of PSA screening in 1986 has resulted in more than 1.3 million additional men in the US being diagnosed with the disease, the study authors reported. "If all cancers detected early were destined to become clinically evident, the number of individuals diagnosed with cancer would be unaffected by screening," they wrote in the Journal of the National Cancer Institute. "However, in practice, early detection efforts have been associated with dramatic rises in incidence, raising the spectre of over-diagnosis," they said, referring to the detection of cancers that don't progress to cause symptoms or death. An accompanying editorial claimed prostate cancer screening had been adopted prematurely. Prostate cancer incidence in the US rose by 26% between 1986-2005, with the most marked increases occurring in younger age brackets, the study found. Diagnosis rates soared by a factor of seven in those younger than 50, more than tripled in men aged 50-59, and almost doubled in those aged 60-69, the authors reported. Under a best-case scenario, the entire decline in prostate cancer mortality since the introduction of PSA screening was attributable to the additional diagnoses, the authors said. But even then, for each man who experienced the presumed benefit of screening, an extra 18 men had to be treated for prostate cancer that would have been best left alone, they estimated. But Australian experts have countered that a degree of overdiagnosis is -- for now -- a necessary consequence of trying to limit the number of prostate cancer deaths. Professor Phillip Stricker, chairman of the department of urology at Sydney's St Vincent's Hospital, said PSA screening had been shown by previous research to have slashed 10-year prostate cancer mortality by more than 20%. Rates of over-treatment would fall in coming years, Professor Stricker predicted, as clinicians became more selective in their use of active surveillance, guided by markers that could indicate the severity of individual cancers. Professor Tony Costello, head of the urology department at Royal Melbourne Hospital, said: "There is something in the molecular pathology we haven't found yet that will tell us, this [cancer] is going to kill this guy while this one won't. In the meantime, if it were me, I'd opt for screening and treatment, and take the punt on keeping my potency and continence." Journal of the National Cancer Institute 2009; 101:1-5....