Prostate cancer metastases lowered by long-term PSA followup?

In a european study of 35,153 men aged 55-69 were followed for 18 years. The men were randomized to either have a program of exams with regular PSA testing or to be followed based on physical exams alone. Of the groups, 11.6% of the PSA-tested men were found with prostate cancer, compared to 5.1% of those without regular PSA testing. Those men having regular PSA screening were later at lower risk of having metastatic disease, with a relative risk reduction of 30%. It took seven years of observation for the difference to show itself, reflecting the very slow nature of prostate cancer development. The same data said the 357 men needed to be screened to prevent one metastasis, which is a big number. Number needed to treat (NNT) is an interesting way to look at this. NNT for statins in patients without heart disease is over 1000. Avandia which lowers blood sugar and Zetia given to lower cholesterol are also over 1000 for NNT to prevent an adverse event.