The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial assessed the effect of screening with prostate-specific antigen and a digital rectal examination on prostate cancer mortality. Another endpoint of interest was the burden of total metastatic disease.
All men in PLCO were assessed for metastatic prostate cancer at diagnosis; men with clinical stage I/II disease were assessed for metastatic progression. The rate of total metastatic disease was defined as metastases found either at diagnosis or through progression divided by person-years (PYs) of follow-up for all men in the trial. Metastatic progression rates were computed among men with clinical stage I/II prostate cancer. Survival among men with metastases at diagnosis was compared with survival among men with metastatic progression.
Among 38,340 men in the intervention arm and 38,343 men in the control arm in PLCO, there were 4974 and 4699 prostate cancer cases, respectively. The rates of total metastatic disease were 4.72 and 4.83 per 10,000 PYs in the intervention and control arms, respectively (rate ratio, 0.98; 95% CI, 0.81-1.18). The rates of metastatic progression among men with clinical stage I/II prostate cancer were 43.7 and 50.5 per 10,000 PYs in the intervention and control arms, respectively (P = .30). Prostate cancer-specific 5- and 10-year survival rates were significantly worse for men with metastatic progression (24% and 19%, respectively) than men with metastases at diagnosis (40% and 26%, respectively).
Rates of total metastatic disease and metastatic progression were similar across arms in PLCO. Survival was worse for men with metastatic progression in comparison with those with metastatic disease at diagnosis.