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Rates of postcolonoscopy colorectal cancer diagnoses at the 3 year mark are similar among veterans than the rates of cancer detected by a colonoscopy.¹

A team, led by Charles J. Kahi, MD, MSc, Department of Medicine, Richard L. Roudebush Veterans Affairs (VA) Medical Center, identified the prevalence of postcolonoscopy colorectal cancer and its all-cause mortality and colorectal cancer-specific mortality within the VA health care system.

Colonoscopies at the VA

While colonoscopies are commonly performed at Veterans Affairs health care facilities, the prevalence of postcolonoscopy colorectal cancer, where colorectal cancer is diagnosed following a colonoscopy in which no cancer was found, and its associated mortality is not currently known.

In the retrospective cohort study, the investigators gathered data from the VA-Medicare administration on 29,877 veterans aged 50-85 years with newly diagnosed colorectal cancer between 2003-2013. Each patient had a colonoscopy less than 6 months prior to a colorectal cancer diagnosis with no other colonoscopies in the previous 36 months or had a colonoscopy that did not detect colorectal cancer between 6-36 months prior to a diagnosis.

There was also a third group that included patients with colorectal cancer, but no colonoscopy within the previous 36 months.

The median age of the patient population was 67 years and 98% (n = 29,353) of patients were male. In addition, 6% (n = 1785) were classified as having postcolonoscopy colorectal cancer at year 3 and 73% (n = 21,811) had detected colorectal cancer.

Comparing Results

To compare postcolonoscopy colorectal cancer at the 3 year mark and detected colorectal cancer 5 year all-cause mortality and colorectal cancer specific mortality following a colorectal cancer diagnosis.

The 5 year all-cause mortality rate was 46% in the postcolonoscopy colorectal cancer 3 year group, compared to 42% in the detected colorectal cancer group. In addition, the 5 year colorectal cancer specific mortality was 26% in the postcolonoscopy colorectal cancer 3 year group, similar to the 25% in the detected colorectal cancer group.

After conducting a multivariable Cox proportional hazards regression analysis, the investigators found no significant difference in all-cause mortality and colorectal cancer specific mortality between the postcolonoscopy colorectal cancer 3 year group (adjusted hazard ratio [aHR], 1.04; 95% confidence interval [CI], 0.98-1.11; P = .18) and patients with detected colorectal cancer (aHR, 1.04; 95% CI, 0.95-1.13; P = .42).

Patients with no prior coloscopy had significantly higher all-cause mortality (aHR, 1.76; 95% CI, 1.70-1.82; P < .001) and colorectal cancer specific mortality (aHR, 2.22; 95% CI, 2.12-2.32; P < .001) compared to patients with detected colorectal cancer.

Finally, compared to patients with detected colorectal cancer, patients with postcolonoscopy colorectal cancer at year 3 had significantly lower odds of having undergone colonoscopy performed by a gastroenterologist (odds ratio [OR], 0.48, 95% CI, 0.43-0.53; P <.001).

“This study found that PCCRC-3y constituted 6% of CRCs in the VA system, which is similar to other settings,” the authors wrote. “Compared with patients with CRC detected by colonoscopy, those with PCCRC-3y have comparable ACM and CSM.”

References:

Kahi CJ, Myers LJ, Monahan PO, Barker BC, Stump TE, Imperiale TF. Mortality After Postcolonoscopy Colorectal Cancer in the Veterans Affairs Health Care System. JAMA Netw Open. 2023;6(4):e236693. doi:10.1001/jamanetworkopen.2023.6693