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Contrasts in colorectal cancer incidence and mortality in screening trials of sigmoidoscopy versus colonoscopy (NordICC).

About this Publication
Title
Contrasts in colorectal cancer incidence and mortality in screening trials of sigmoidoscopy versus colonoscopy (NordICC).
Pubmed ID
40971678 (View this publication on the PubMed website)
Digital Object Identifier
Publication
J Natl Cancer Inst. 2025 Sep 14
Authors
Meester RGS, Miller EA, Pinsky PF, Schoen RE, Ladabaum U
Affiliations
  • Division of Gastroenterology & Hepatology, Stanford University School of Medicine, Stanford, CA, USA.
  • Division of Cancer Prevention, National Cancer Institute, Rockville, MD, USA.
  • Departments of Medicine and Epidemiology, University of Pittsburgh, Pittsburgh, PA, USA.
Abstract

BACKGROUND: Interim 10-year results from the Nordic-European Initiative on Colorectal Cancer (NordICC), a randomized controlled trial (RCT) of screening colonoscopy, demonstrated a statistically significant reduction in colorectal cancer (CRC) incidence but not mortality, contrary to results from four flexible sigmoidoscopy (FS)-RCTs.

METHODS: We constructed CRC incidence and mortality Kaplan-Meier curves through 10 years to standardize comparisons across RCTs, and examined CRC screen-detection and stage. Novel analyses of one FS-RCT (Prostate, Lung, Colorectal, and Ovarian cancer screening trial [PLCO]) assessed year-by-year mortality in screen-detected CRCs.

RESULTS: At 10 years, all five RCTs demonstrated statistically significant CRC incidence reductions with screening (ratios = 0.77 [95%CI 0.70-0.84] to 0.82 [0.69-0.97] vs controls; P ≤ .011). Two FS-RCTs and NordICC showed no significant CRC mortality reduction (ratios = 0.84 [0.64-1.10] to 0.90 [0.69-1.18]; P = .10-0.23). In three FS-RCTs and NordICC, relative reductions were greater in CRC incidence than CRC mortality, but only NordICC reported higher CRC mortality with screening vs controls for the first 7 years. In contrast, PLCO observed fewer CRC deaths with screening by year 2 (ratio = 0.59, P = .03), and screen-detected CRCs were less often advanced (OR = 0.26; P < .001) or fatal (ratio = 0.50; P < .001).

CONCLUSIONS: After 10 years, NordICC is similar to two FS-RCTs in observing statistically significant reductions in CRC incidence but not CRC mortality. However, only NordICC observed greater CRC mortality with screening vs controls for 7 years. Granular analyses of CRC cases and deaths in NordICC, paralleling our PLCO analyses, could provide insight into why CRC mortality results differ in NordICC vs FS-RCTs.

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