N. Kim1, S. W. De Geus2, A. D. Geary2, S. Ng2, J. F. Hall1, J. F. Tseng2, U. Phatak1 1Boston Medical Center,Department Of Colorectal Surgery,Boston, MA, USA 2Boston Medical Center,Department Of General Surgery,Boston, MA, USA
Introduction: Robotic surgery for colorectal disease is rapidly gaining popularity. However, the impact of hospital volume on the outcomes of robotic surgery (RS) versus laparoscopic surgery (LS) remains unclear. This study investigates from the National Cancer Database whether hospital volume is a factor in determining the short- and long-term outcomes of RS versus LS for rectal cancer.
Methods: Patients with stage I-III rectal cancer who underwent RS or LS between 2011 and 2014 were identified from the National Cancer Database. Institutions were defined as being either low-volume hospitals (LVH: 15 operations/year) or high-volume hospitals (HVH> 15 operations/year). Propensity-scores for the probability of undergoing RS were created within each volume group. Patients were matched based on propensity-score. Within each group, conversion rates, positive margin rates, readmission rates, 30-day and 90-day mortality, length of stay, number of lymph nodes dissected and overall survival were compared between patients who had RS vs LS. Survival analysis was performed using the Kaplan-Meier method.
Results: 8,235 patients underwent minimal invasive surgery for rectal cancer. Overall, 28.8% (n=2,374) of resections were performed robotically. Rectal cancer surgery at a HVH was associated with lower positive resection margins (5.0% vs. 6.3%; p=0.0080), lower rates of conversion to open (11.2% vs. 15.7%; p<0.0001), and 90-day (1.7% vs. 2.7%; p=0.0009) mortality. After matching, conversion rates were significantly lower after RS compared to LS (LVH: 10.1% vs. 18.8%; p<0.0001; HVH: 6.3 vs. 13.4; p<0.0001). There following factors were not significant for patients that received either RS or LS; positive margins rates (LVH: 5.5% vs. 6.9%; p=0.2014; HVH: 5.1% vs. 4.8%; p=0.7211), number of lymph nodes resected (LVH: 14 vs. 15 nodes; p=0.4129; HVH: 16 vs. 16 nodes; p=0.5739), median length of stay (LVH: 5 vs. 5 months; p=0.1324; HVH: 5 vs. 5 months; p=0.1324), readmission (LVH: 9.3% vs. 7.3%; p=0.0936; HVH: 8.9% vs. 8.9%; p=0.9460), 90-day mortality (LVH: 2.3% vs. 2.7%; p=0.5742; HVH: 1.2% vs. 1.9%; p=0.1567) and overall 3 year survival (LVH: 86.9% vs. 86.7%; log-rank p=9148; HVH: 88.6% vs. 88.6%; log-rank p=0.5114).
Conclusion: Although outcomes after major operations are influenced by various factors beyond hospital volume alone, the results of this study suggest that patients with rectal cancer are at higher risk of having positive resection margins, higher rates of conversion to open and 90-day mortality if they are treated at LVH as opposed to at HVH. However, for both high- and low-volume hospitals, robotic resections of rectal cancer were associated with surgical and oncologic outcomes that were similar to those for laparoscopic operations. Although residual selection bias regarding RS vs LS must be acknowledged, our data suggest that robotic colorectal resections when feasible is a reasonable approach across hospital volume strata.