Annual prostate cancer screening tied to high overdetection rate

Half of the prostate cancers that are detected in older men with an annual screening program probably would never have become apparent during their lifetime, according to a new report. This high overdetection rate suggests that screening intervals should be longer than 1 year.

Dr. Gerrit Draisma, from the University Medical Center Rotterdam in the Netherlands, and colleagues created a simulation model based on data from a cancer screening study involving 42,376 men, to assess the effect of various screening intervals on overdetection rates and on lead times — the amount of time that screening advances diagnosis. The researchers’ findings are published in the June 18th issue of the Journal of the National Cancer Institute.Average lead times and overdetection rates depended on age at screening, the investigators note. For example, the mean lead time for a single screening test at age 55 was 12.3 years, while the lead time was only 6 years for screening at age 75. The corresponding overdetection rates were 27% and 56%.A 4-year screening interval from age 55 to 67 was tied to a 65% increase in the lifetime risk of a prostate cancer diagnosis and a 48% overdetection rate, the researchers state. If annual screening was applied from age 55 to 67 the lifetime risk of a prostate cancer diagnosis increased by 80% and the overdectection rate was 50%.Extending annual or 4-year screening until age 75 would result in two overdetected cases for every clinically relevant cancer, the authors point out.”These lead-time estimates, which are the first to be based on results of a large-scale, screening trial for prostate cancer in a population-based setting, support a screening interval of more than 1 year,” Dr. Draisma’s team states.”The net balance of favorable and unfavorable effects of screening remains to be established,” the authors conclude.(Source: J Natl Cancer Inst 2003;95:868-878: Reuters Health: June 17, 2003)