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IMPACT ON SURVIVAL OF SCREENING AND DIAGNOSTIC COLONOSCOPIES IN COLON AND RECTAL CANCER.
Lieve G. Leijssen*1,2, Anne M. Dinaux1,2, Hiroko Kunitake1,2, Liliana G. Bordeianou1,2, David L. Berger1,2
1General and Gastrointestinal Surgery, Massachusetts General Hospital, Somerville, MA; 2Harvard Medical School, Boston, MA
Background
Identifying colorectal cancer at an early stage improves long-term outcomes. In the United States, screening programs have been established on an opportunistic basis and the average risk population (50-75 years) are encouraged to undergo screening beginning at age 50. We aimed to assess the difference in prognosis between screening (SC) and diagnostic colonoscopies (DC) which identified a colorectal cancer. In addition, we analyzed the differences between colon and rectal cancer.
Methods
We performed a retrospective analysis of a prospectively maintained database, including all patients who underwent surgery for primary colon (CC) or rectal cancer (RC) at a tertiary center between 2004-2014. The diagnostic group included only symptomatic patients whom required a colonoscopy. Patients with a history of adenomas, colorectal cancer, IBD, or a positive family history were excluded from both cohorts.
Results
We included 1516 patients, of whom 364 (24.0%) underwent a SC and 1152 (76.0%) DC. Screening was correlated with colon cancer, male gender, lower ASA-score, and lower T-staging (T0-T2, P<0.001). 1053 (69.5%) patients had colon cancer and 463 (30.5%) had rectal cancer. CC patients who underwent a DC demonstrated more advanced disease (T3-T4, and N+, P<0.001) and poor histological features including EMVI, LVI, MSI, and perineural invasion (P<0.01) than SC-CC patients. Within the RC cohort, the only significant differences between SC and DC were more T2 and T3 tumors as well as more perineural invasion in the DC group. Stage III and IV disease diagnosed through DC was equally distributed between CC (45.3%) and RC (39.8%). In follow-up, symptomatic CC patients were at risk of worse overall survival (RR 1.60, P<0.001) and colon cancer specific survival (RR 1.86, P<0.001). There was no difference in long-term outcomes in rectal cancer. Kaplan Meier curves demonstrated significantly worse overall survival for DC-CC patients (mean 118.8 vs. 89.8 months, P<0.001). When analyzing stage-by-stage, DC-CC patients with stage I (mean 141.1 vs. 101.9, P0.001) and stage IV (mean 57.6 vs. 37.8, P0.010) disease had significant worse overall survival. Outcomes for the rectal cohort (mean 105.9 vs. 96.6 months, P0.128), as well stage-by-stage, were similar between SC-RC and DC-RC patients.
Conclusion
This study demonstrated the enormous impact of asymptomatic screening in colon cancer. Patients with colon cancer diagnosed through screening had significantly better prognosis compared to colon cancer patients who presented with symptoms. Conversely, the impact on survival rates was not seen in rectal cancer patients.
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