(HealthDay News) — The risk for colorectal cancer death drops with an increasing number of prediagnostic colonoscopies, largely due to fewer advanced cancers at time of diagnosis, according to a study recently published in BMC Cancer.
Ming Li, Ph.D., from the University of South Australia in Adelaide, and colleagues used linked Medical Benefits Schedule claims and hospital-inpatient and cancer-registry data to assess colonoscopy histories of colorectal cancer patients diagnosed from 2003 to 2013 in South Australia.
The researchers found that having a prediagnostic colonoscopy was associated with an unadjusted reduction in risk for colorectal cancer death of 17 percent (subhazard ratio, 0.83). The risk for colorectal cancer death was reduced by 17 percent for one prediagnostic colonoscopy examination, 27 percent for two prediagnostic colonoscopy examinations, and 45 percent for at least three prediagnostic colonoscopy examinations, when adjusting for time period and sociodemographic characteristics. There was also a 17 percent lower risk for colorectal cancer death among patients with more than one year from first colonoscopy to diagnosis versus patients with less than one year. However, reductions in cancer death risk were substantially reduced or eliminated when also adjusting for less advanced stage of disease.
“The reduced risk of colorectal cancer death with multiple colonoscopy examinations, and longer time from first colonoscopy examination, is indicative of a benefit from screening or surveillance of high-risk patients, since it would largely exclude colonoscopies undertaken close to cancer diagnosis in response to symptoms,” the authors write.