Impact of Screening Colonoscopy on Outcomes in Colon Cancer Surgery

Abstract

Importance: Screening colonoscopy seemingly decreases colorectal cancer rates in the United States. In addition to removing benign lesions and preventing progression to malignancy, screening colonoscopy theoretically identifies asymptomatic patients with early-stage disease, potentially leading to higher survival rates. Objectives: To assess the effect of screening colonoscopy on outcomes of colon cancer surgery by reviewing differences in staging, disease-free interval, risk of recurrence, and survival and to identify whether diagnosis through screening improves long-term outcomes in- dependent of staging. Design: Retrospective review of prospectively maintained, institutional review board-approved database. Setting: Tertiary care center with high patient volume. Patients: All patients who underwent colon cancer surgery at Massachusetts General Hospital from January 1, 2004, through December 31, 2011. Intervention: Colon cancer surgery. Main Outcomes and Measures: Postoperative staging, death, and recurrence, measured as incidence and time to event. Results: A total of 1071 patients were included, with 217 diagnosed through screening. Patients not diagnosed through screening were at risk for a more invasive tumor (≥T3: relative risk [RR]=1.96; P<0.001), nodal disease (RR=1.92; P<0.001), and metastatic disease on presentation (RR=3.37; P<0.001). In follow-up, these patients had higher death rates (RR=3.02; P<0.001) and recurrence rates (RR=2.19; P=0.004) as well as shorter survival (P<0.001) and disease-free intervals (P<0.001). Cox and logistic regression controlling for staging and base- line characteristics revealed that death rate (P=0.02) and survival duration (P=0.01) were better stage for stage with diagnosis through screening. Death and metastasis rates also remained significantly lower in tumors without nodal or metastatic spread (all P<0.001). Conclusions and Relevance: Patients with colon cancer identified on screening colonoscopy not only have lower-stage disease on presentation but also have better outcomes independent of their staging. 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.