The reduction in colorectal cancer mortality after colonoscopy varies by site of the cancer.
OBJECTIVE
There are limited data on mortality from colorectal cancer (CRC) among patients who have received colonoscopy examinations. We sought to determine CRC mortality among persons undergoing colonoscopies compared with the general population.


METHODS
We identified all individuals who had a colonoscopy as their first lower gastrointestinal endoscopy from April 1, 1987, to September 30, 2007 (24,342 men and 30,461 women), based on information from Manitoba's provincial physicians' billing claims database. Patients were followed until March 31, 2008, death, or migration out of the province (310,718 person-years). Individuals less than 50 years of age or more than 80 years of age at the index colonoscopy or those with prior sigmoidoscopy, inflammatory bowel disease, resective colorectal surgery, or CRC were excluded. CRC mortality after the index colonoscopy was compared with that of the general population by standardized mortality ratios (SMRs). Stratified analyses were performed to determine CRC mortality for different age groups at index colonoscopy and sex, duration of follow-up, medical specialty of the endoscopist, and site of CRC.


RESULTS
There was a 29% reduction in overall CRC mortality (SMR, 0.71; 95% confidence interval [CI], 0.61-0.82], a 47% reduction in mortality from distal CRC (SMR, 0.53; 95% CI, 0.42-0.67), and no reduction in mortality from proximal CRC (SMR, 0.94; 95% CI, 0.77-1.17). The reduction in mortality from distal CRC remained significant for follow-up beyond 10 years (SMR, 0.53; 95% CI, 0.31-0.84).


CONCLUSIONS
In Manitoba, colonoscopies significantly reduce mortality from CRC, but the benefit is not uniform for colorectal tumors that arise in different areas of the colon.
Singh
Harminder
H
Internal Medicine and University of Manitoba IBD Clinical and Research Centre, Winnipeg, Manitoba, Canada. singh@cc.umanitoba.ca
Nugent
Zoann
Z
Demers
Alain A
AA
Kliewer
Erich V
EV
Mahmud
Salaheddin M
SM
Bernstein
Charles N
CN
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000517:prevention & control; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors