Robert Schoen

MD MPH

U. of Pittsburgh

Professor of Medicine and Epidemiology

PLCO (Learn more about this study)

PLCO-1346

Oct 4, 2023

Evolution of cancer stage and mortality in the PLCO trial

The interim 10 yr results from the NordICC colonoscopy study were recently reported in the NEJM (bretthauer, M. NEJM 2022). In the intention to screen analysis, the crossover in incidence from increased rate in the screening group compared to control occurred around year 6, later than that observed in PLCO and the other flexible sigmoidoscopy trials (years 3-5). Moreover, no appreciable effect on CRC mortality was observed through 10 years of follow up. The reasons for the lack of an observable effect on CRC mortality are unclear. In the flexible sigmoidoscopy trials, a consistent and predictable effect on mortality was observed. The divergence in the mortality curves begins rather early on. We propose to study the PLCO chronological evolution of cancer incidence, stage and mortality in granular detail. it is assumed that in the screening arm in the initial years of the trial, early-stage prevalent cancers are identified, and those early-stage lesions and less likely to lead to CRC mortality, contributing to the initial divergence of the CRC mortality curves. Subsequently, the effect of polypectomy on reducing incident CRC disease emerges, and absolute reductions in CRC incidence emerge.