Screening Colonoscopy Associated with Increased Survival Duration and Rates for Patients with Colon Cancer
Patients with colon cancer identified on screening colonoscopy appear to have lower-stage disease on presentation and better outcomes independent of their staging, according to a report published online today in JAMA Surgery.
Since their introduction in 2000, National Institutes of Health (NIH)–recommended screening colonoscopy guidelines seemingly have consistently decreased overall rates of colorectal cancer in the United States. From 2002 to 2005, the U.S. Surveillance, Epidemiology, and End Results (SEER) database reported 4.0% annual decreases in the incidence of colon cancer, and from 2005 to 2009 the annual decrease was 2.4%.
Ramzi Amri, MSc, and colleagues of Massachusetts General Hospital and Harvard Medical School, Boston, examined the association of screening colonoscopy with outcomes of colon cancer surgery by reviewing differences in staging, disease-free interval, risk of recurrence, and survival and aimed to identify whether diagnosis through screening was associated with long-term outcomes independent of staging.
Retrospective Review
The investigators conducted a retrospective review of a prospectively maintained, institutional review board–approved colon cancer database at Massachusetts General Hospital. A total of 1,071 patients were included in the study, with 20.3% of patients diagnosed through screening colonoscopy and 79.7% diagnosed through nonscreening methods.
In a review of baseline characteristics, patients in the nonscreening group were older (mean difference, 4.6 years, P < .001), had a higher rate of metastatic disease on presentation (relative risk [RR] = 3.37, P < .001), and had a lower body mass index (mean difference, 1.2; P =.001), while patients in the screening group were more likely to be male (P = .049).
Nonscreening Population at Higher Risk
Patients not diagnosed through screening were at higher risk for having more invasive tumors according to TNM staging (≥ T3: RR = 1.96, P < .001), nodal disease (RR = 1.92, P < .001), and stage M1 pathology (RR = 6.08, P < .001). In follow-up, these patients had higher death rates (RR = 3.02, P < .001) and recurrence rates (RR = 2.19, P = .004), as well as shorter survival (P < .001) and disease-free intervals (P < .001).
After controlling for staging and baseline characteristics, the authors found that death rate (P = .02) and survival duration (P = .01) were better stage-for-stage with diagnosis through screening. Death and metastasis rates also remained lower among patients with tumors without nodal or metastatic spread (all P < .001).
According to the authors, these results further emphasize the “tremendous effect” that early diagnosis has on prognosis. “Compliance to screening colonoscopy guidelines can play an important role in prolonging longevity, improving quality of life, and reducing health-care costs through early detection of colon cancer,” they concluded.
The study was conducted with support from Harvard Catalyst/The Harvard Clinical and Translational Science Center, the National Center for Research Resources and National Center for Advancing Translational Sciences, Harvard University and its affiliated health-care centers, the Dutch Cancer Society, the Dutch Digestive Society, the Amsterdam University Funds, and the Fulbright Foundation. The authors reported no potential conflicts of interest.
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