ASSOCIATION BETWEEN SURGICAL VOLUME AND MORTALITY FROM COLON CANCER IN COLOMBIA: A NATIONAL COHORT.

Background: Colon cancer is the third most common malignancy in Colombia, only exceeded by prostate and breast cancers. It is the second most common cancer among females and the third most common among males. The epidemiology of this disease has changed in Colombia, and its peak incidence has now surpassed that of gastric cancer.

Aims: We aimed to determine the association between hospital surgical volume and mortality in patients with colon cancer undergoing surgical resection in Colombia.

Methods: This was a national retrospective cohort study based on administrative data and included adult patients undergoing surgical resection for colon cancer who were enrolled in Colombia's contributory health system between 2012 and 2017. We defined exposure as the hospital's surgical volume where the colon cancer surgery was performed. We classified the patients as exposed to a high surgical volume (above the 90th percentile of the provider distribution) and a low surgical volume (under the 90th percentile). The main outcomes were 30-day and 1-year mortality. Multivariate Poisson regressions were used to identify the association between exposure and mortality rates.

Results: The study included 4,647 patients, of which 4,188 underwent surgery at hospitals with a colectomy volume lower than 33 per year and 459 underwent surgery at institutions with volumes equal to or higher than 33 per year. In the multivariate analysis, after adjusting for observable variables, a lower risk of 30-day mortality was found in patients who underwent surgery at high surgical volume institutions (relative risk - RR 0.57, 95% confidence interval - 95%CI 0.033-0.97). No differences were found in the one-year mortality.

Conclusion: The high surgical volume of a hospital is associated with a 30-day mortality in colon cancer, as described in other studies, but the 1-year mortality did not show this association. Prospective studies are required to establish a causal relationship.