Canadian patients whose previous negative colonoscopies were performed by gastroenterologists are less likely to have subsequent colorectal cancer than are patients whose screens were done by other specialists, including general surgeons, Dr. Linda Rabeneck and her colleagues reported.
Despite previous studies finding a significantly decreased risk of colorectal cancer (CRC) even 10 years following a negative colonoscopy, “a small but clinically meaningful number of incident CRCs occur,” wrote Dr. Rabeneck of the University of Toronto (Clin. Gastroenterol. Hepatol. 2010 March [doi:10.1016/j.cgh.2009.10.022]).
These cancers could include missed lesions because of poor bowel preparation, suboptimal colonoscopy technique, incomplete polypectomy, or even truly new cancers, the authors write. However, “The issue of whether endoscopist characteristics, including colonoscopy volume and specialty, are important in this context has not been previously addressed in a large-scale … population-based study that reflects usual clinical practice.”
Dr. Rabeneck and her colleagues studied 110,402 Ontario residents aged 50-80 years who had a negative complete colonoscopy between Jan. 1, 1992, and Dec. 31, 1997. Participants had no history of colorectal cancer, no past diagnosis of inflammatory bowel disease, and no colonic resection within 5 years of the index colonoscopy.
Patients were followed up for colorectal cancer diagnosis from the date of the index negative colonoscopy through Dec. 31, 2006. During the study's 15-year follow-up period, colorectal cancer “was diagnosed in 1,596 persons, of whom 1,426 had the index colonoscopy in a hospital [86%], and 170 had the procedure in a private office/clinic,” wrote the authors.
Among patients who had colonoscopies performed in a hospital, 38% of endoscopists were general surgeons and 17% were gastroenterologists, with the remainder classified as “other”: primarily internists, family physicians, and “general physicians.” Regarding these hospital-based patients, the authors wrote: “For those who had their procedures performed by a general surgeon, the risk of incident CRC was increased by almost 40% (hazard ratio 1.389), compared with those who had their procedures performed by a gastroenterologist.”
Patients whose hospital-based colonoscopies were performed by physicians classified in the “other” category (primarily internists) also were at higher risk for a subsequent colorectal cancer diagnosis (HR 1.275).
In the office-based setting, however, “in which only 14% of procedures were performed, and where only 8.1% of procedures were performed by a gastroenterologist … endoscopist specialty was not significantly associated with incident CRC.” Nor was there any association between the volume of colonoscopies previously performed by the endoscopist and incident CRC in either setting, after adjustment for patient age, sex, and comorbidity.
The authors attempted to explain the disparate findings between the office and hospital settings by pointing out that patients seen in the private office/clinics were younger, more likely to be men, and had less comorbidity. Therefore, “It is likely that the procedures in the private office/clinics were technically easier to perform,” they said.
“Most general surgery trainees have 2 months of dedicated endoscopy training in their programs. Gastroenterology trainees have dedicated endoscopy training for a minimum of 16 months during their programs,” they added. “Having extensive formal training matters more when the procedures are more challenging to perform.”
The authors reported no conflicts of interest related to this study.