P-290 - Prognostic value of repeat testing in population screening for CRC - for optimizing efficacy

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Cancer Aetiology, Epidemiology, Prevention
Colon Cancer
Rectal Cancer
Presenter P. Elsakov
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors P. Elsakov1, R. Meskauskas2, L. Skrickiene1
  • 1Centre Policlinic Diagnostic Centre, Vilnius/LT
  • 2National Pathology Centre, Vilnius/LT

Abstract

Introduction

Population screening for those average risk for CRC by FOBT every two years can reduce mortality from this cancer, when participation rate reach 45-60% of population. The choice of FOBT kits for screening impacts on participation rates and efficacy of such programs. This makes it possible to search for a minimal cost, least demand on resources and inconvenience to the screener for optimal efficacy.

Methods

From May 2009 using the FIT with automated processing (OC-Sensor™ test) screening started for a target population of 36.062 subjects – 14.559 (40,4%) males and 21.503 (59,6%) females between the ages of 50-74 years. General practitioners distributed test kits to patients attending consultations for whatever reason. In the first round 5.214 patients (Group 1) were screened with 2 consecutive tests and 15.022 patients (Group 2) of similar age and CRC risk, were screened with a single test. Patients with negative test results in the second round of testing (two years later) in both groups were screened by a single test. Those with an FIT value ≥100-ng Hb/mL of buffer underwent colonoscopy. Comparative efficacy the participation rates with positive test rates results - of these two groups were calculated using a two-tailed statistical test.

Results

The participation (sample return) rate for initial screening for both groups (returning kits 1 or 2 samples) was 56,1% (20.236/36.062). Positive test results were found in 8.7% (455/5214) of Group 1 and in 7,3% (1095/15022) of Group 2 subjects. The participation rate of repeat testing of negative test patients 2 years later was 46.8% (2141/4579) in Group 1 and 52,2% (7273/13927) in Group 2. The over all participation rate for repeat testing in both Groups, after two years - was 26,1% (9414/36062). Positive test results were found in 4,2% (89/2141) and 5,7% (414/7273) of Group 1 & 2 subjects, respectively. Participation rate were significantly better in the second round for subjects who in the first round were tested with single faecal samples - 52,2% (p < 0.01) compared to those who provided 2 faecal samples - 46,8%. Positive test result rates significantly decreased from 8,7% to 4,2% (p < 0.01) in Group 1subjects who provided 2 faecal samples, and from 7,3% to 5,7% (p < 0.01) in Group 2 subjects who were screened with a single test.

Conclusion

The participation rates for repeat testing is 26,1% less than the necessary minimum of - 45%, that is needed to be of benefit to reduce expected mortality rates. Screening by single FIT (value ≥100-ng Hb /mL of buffer) is significantly more efficacious demanding less of the screener, and saves resources.