Comparing patients who died from colorectal cancer (CRC) with a larger control group, researchers writing in the Journal of Clinical Oncology found that those who had undergone optical colonoscopy were far less likely to have died.
Although a mortality benefit from colonoscopy is strongly implied in the literature, it has not been firmly established. The study from the University of Toronto and other centers in the U.S. and Canada found that CRC patients who had died were less likely to have undergone colonoscopy than the controls -- with a stronger association for distal cancers compared to proximal cancers, where colonoscopy may be less effective in saving lives.
In addition, patients whose colonoscopy had been performed by a gastroenterologist were better off in terms of survival than those who received a colonoscopy from a nongastroenterologist (Journal of Clinical Oncology, June 11, 2012).
The case-controlled study examined Surveillance, Epidemiology, and End Results (SEER) Medicare data for patients 70 to 89 years of age from 1998 to 2002 who died of colorectal cancer by 2007. Three matched controls without cancer were used for each case, explained Dr. Nancy Baxter from the University of Toronto.
Conditional logistic regression analysis was used to compare colonoscopy exposure in cases and controls, stratified by the site of CRC, and physician specialty was also determined and associated with outcomes.
The 9,458 cases (3,963 proximal, 4,685 distal, and 810 unknown site) were compared with 27,641 controls. A total of 11.3% of cases and 23.7% of controls underwent colonoscopy more than six months before diagnosis.
Compared with the controls, the cases were less likely to have undergone colonoscopy (odds ratio [OR], 0.40; 95% confidence interval [CI]: 0.37-0.43); the association between undergoing colonoscopy and survival was stronger for distal (OR, 0.24; 95% CI: 0.21-0.27) CRC cases than proximal (OR, 0.58; 95% CI: 0.53-0.64) cases, the group reported.
"Colonoscopy is associated with a reduced risk of death from CRC, with the association considerably and consistently stronger for distal versus proximal CRC," Baxter and colleagues wrote. "The overall association was strongest if colonoscopy was performed by a gastroenterologist."
