Colonoscopy Could Prevent 40% of Colorectal Cancers

A large, long-term study from Harvard School of Public Health suggests that 40% of all colorectal cancers might be prevented if we all underwent regular colonoscopy screenings.

Background: In the USA, nearly 137,000 people were found to have colon cancer in 2009, and nearly 52,000 died that year from the diserase. Colorectal cancer is the second-leading cause of cancer-related death in the USA.

The Study: Researchers analyzed data from 88,902 participants in two long-term studies (the Nurses’ Health Study and the Health Professionals Follow-up Study). Based on questionnaires that participants filled out every two years between 1988 and 2008, the researchers obtained information on colonoscopy and sigmoidoscopy procedures. They documented 1,815 cases of colorectal cancer, and 474 deaths from the disease.

Findings: Both colonoscopy and sigmoidoscopy (the latter screens for cancer in the distal, lower part of the colorectal) lowered the risk of either getting colorectal cancer or dying from it. Only colonoscopy decreased the risk for cancers in the upper (proximal) colon, but not to the degree that it did for lower colorectal cancers.

  1. If all participants had undergone colonoscopy, 40% of colorectal cancers (including 61% distal, and 22% proximal) would have been prevented.
  2. Sigmoidoscopy alone is likely insufficient for reducing the risk of upper colon cancer.
  3. People who get an all-clear report from their colonoscopy have a significantly lower chance of colorectal cancer for up to 15 years after the procedure (although the data support repeat screening at shorter intervals among individuals with a personal history of an adenoma (a benign tumor of the colon, but one that can become cancer over time; also, more frequent if you have higher risk features such as a family history of the disease).
  4. Colorectal cancers found within 5 years of colonoscopy had different molecular characteristics, compared with cancers found more than 5 years after a colonoscopy, and may be more difficult to detect or completely remove.

My Take: This new research supports our current guidelines that call for a colonoscopy every 10 years for those at average risk for colon or rectal cancer. The reduction in risk of getting (or dying from) colon cancer is large. I’m Dr. Michael Hunter, and yes I am due this year for my own colonoscopy. Are you?

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

Reference: Reiko Nishihara, Kana Wu, Paul Lochhead, Teppei Morikawa, Xiaoyun Liao, Zhi Rong Qian, Kentaro Inamura, Sun A. Kim, Aya Kuchiba, Mai Yamauchi, Yu Imamura, Walter C. Willett, Bernard A. Rosner, Charles S. Fuchs, Edward Giovannucci, Shuji Ogino, Andrew T. Chan. Long-Term Colorectal-Cancer Incidence and Mortality after Lower Endoscopy. New England Journal of Medicine, 2013; 369 (12): 1095 DOI:10.1056/NEJMoa1301969

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Harvard AB Yale MD UPenn Radiation Oncology Radiation Oncologist, Seattle area

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