INDIANAPOLIS, IN — Colonoscopy is heavily promoted in the VA healthcare system, and a new study sought to document its effect on colorectal cancer (CRC) mortality rates.

The goals of the research published in Annals of Internal MedicineM. were both to determine whether colonoscopy is associated with decreased CRC mortality in veterans and to find out whether its effect differs by anatomical location of CRC.1

The case-control study was conducted by a team led by researchers from the Richard L. Roudebush VAMC and Indiana University School of Medicine, both in Indianapolis. VA-Medicare administrative data was used in the investigation.

Participants were veterans 52 or older who were diagnosed with CRC between 2002 and 2008 and died of the disease by the end of 2010. Those nearly 5,000 patients were each matched to four control patients without prior CRC on the basis of age, sex and facility.

For the study, exposure to colonoscopy was determined from 1997 to six months before CRC diagnosis in case patients and to a corresponding date in control patients. Patients who had undergone screening colonoscopy were included in a subgroup analysis.

Results indicated that “case” patients—those who had died of CRC—were significantly less likely to have undergone any colonoscopy (OR, 0.39 [95% CI, 0.35 to 0.43]). Researchers determined that colonoscopy was associated with reduced mortality for left-sided cancer (OR, 0.28 [CI, 0.24 to 0.32]) and right-sided cancer (OR, 0.54 [CI, 0.47 to 0.63]).

The study team noted that results were similar for patients who had undergone screening colonoscopy (overall OR, 0.30 [CI, 0.24 to 0.38]).

“In this study using national VA-Medicare data, colonoscopy was associated with significant reductions in CRC mortality among veterans and was associated with greater benefit for left-sided cancer than right-sided cancer,” the study authors concluded.

1Kahi CJ, Pohl H, Myers LJ, Mobarek D, Robertson DJ, Imperiale TF. Colonoscopy and Colorectal Cancer Mortality in the Veterans Affairs Health Care System: A Case-Control Study. Ann Intern Med. 2018 Apr 3;168(7):481-488. doi: 10.7326/M17-0723. Epub 2018 Mar 6. PubMed PMID: 29532085.