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New Research Further Quantifies Benefits of Preventative Colonoscopy Screening

Key findings

  • In a retrospective cohort of 1,809 patients who had colorectal cancer detected through colonoscopy, patients who had symptoms had significantly reduced survival compared with high-risk patients or asymptomatic average-risk patients
  • The poorer prognosis of patients who had symptomatic colonoscopy persisted after adjustment for stage, tumor site and (neo)adjuvant treatment
  • Patients should be made aware that having a colonoscopy before colon cancer symptoms develop has a tremendous effect on survival

The American Cancer Society recommends that for average-risk adults, screening for colorectal cancer (CRC) should start at age 45 instead of 50. When CRC is identified at an early stage, five-year survival rates are 90% or better.

Because of evidence from large observational studies, colonoscopy is the preferred screening method for CRC in the U.S. However, few studies have examined to what extent colonoscopy benefits higher-risk patients, and long-term data are scarce.

Massachusetts General Hospital researchers Lieve G. J. Leijssen, MD, Anne M. Dinaux, MD, Hiroko Kunitake, MD, of the Massachusetts General Hospital Division of General and Gastrointestinal Surgery, Liliana G. Bordeianou, MD, MPH, chief of the Colorectal Surgery Program at Mass General and David L. Berger, MD, colorectal and gastrointestinal surgeon, have conducted the first study of colonoscopy that distinguishes between screening and surveillance patients and between colon and rectal cancer. They report in Surgical Endoscopy that asymptomatic screening has a tremendous survival benefit.

The Study Cohort

The researchers reviewed 1,809 patients who had CRC diagnosed through colonoscopy and had surgery between January 1, 2004, and December 31, 2015. They divided the cohort into three groups according to the indication for colonoscopy:

  1. Diagnostic (n=1386): Patients who had no prior colonoscopy and reported one or more symptoms associated with CRC or needed evaluation of an abnormality seen on imaging
  2. Screening (n=235): Asymptomatic, average-risk patients who had no prior colonoscopy
  3. Surveillance (n=188): Patients who had a personal history of adenomas or inflammatory bowel disease or a family history of CRC

The researchers included follow-up results until the patient's death or the end of the study on April 30, 2018, whichever came first. The median follow-up period was 45 months.

Multivariate Analyses

After adjustment for age, gender and American Society of Anesthesiologists score, the diagnostic group had a significantly worse prognosis (P < .001 for all comparisons):

Five-year overall survival

  • 64% worse than in the screening group
  • 42% worse than in the surveillance group

Five-year disease-free survival

  • 57% worse than in the screening group
  • 68% worse than in the surveillance group

The poorer overall survival in the diagnostic group persisted even after further adjustment for stage, tumor site and (neo)adjuvant treatment. Survival was 54% worse than in the screening group (P < .001) and 27% worse than in the surveillance group (P = .04).

The Importance of Offering Screening

About one-third of eligible adults in the U.S. have never been screened for CRC. Lack of health insurance is not the only explanation; in one study, more than 75% of unscreened adults were insured.

The problem is worse among younger eligible patients. Federal government data show that 55% of adults ages 50 to 54 have never been screened, versus 28% of those ages 65 to 75.

Now that the American Cancer Society guidelines have changed, the researchers urge an extra effort to boost the adherence of adults 45 to 50 years old. They call on clinicians to reach out to all patients and make them aware of the survival benefit of being screened for CRC before symptoms develop.

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