Trends in utilization, conversion rates, and outcomes for minimally invasive approaches to non-metastatic rectal cancer: a national cancer database analysis.

Background: This study examined utilization and conversion rates for robotic and laparoscopic approaches to non-metastatic rectal cancer. Secondary aims were to examine short- and long-term outcomes of patients who underwent conversion to laparotomy from each approach.

Methods: The National Cancer Database (NCDB) was reviewed for all cases of non-metastatic adenocarcinoma of the rectum or rectosigmoid junction who underwent surgical resection from 2010 to 2016. Utilization rates of robotic, laparoscopic, and open approaches were examined. Patients were split into cohorts by approach. Subgroup analyses were performed by primary tumor site and surgical procedure. Multivariable analysis was performed by multivariable logistic regression for binary outcomes and multivariable general linear models for continuous outcomes. Survival analysis was performed by Kaplan-Meier and multivariable cox-proportional hazards regression.

Results: From 2010 to 2016, there was a statistically significant increase in utilization of the robotic and laparoscopic approaches over the study period and a statistically significant decrease in utilization of the open approach. The conversion rates for robotic and laparoscopic cohorts were 7.0% and 15.7%, p < 0.0001. Subgroup analysis revealed statistically lower conversion rates between robotic and laparoscopic approaches for rectosigmoid and rectal tumors and for LAR and APR. Converted cohorts had statistically significant higher odds of short term mortality than the non-converted cohorts (p  < 0.05).Laparoscopic conversion had statistically higher odds of positive margins (p  < 0.0001) and 30-day unplanned readmission (p  < 0.0001) than the laparoscopic non-conversion. Increased adjusted mortality hazard was seen for converted laparoscopy relative to non-converted laparoscopy (p  = 0.0019).

Conclusion: From 2010 to 2016, there was a significant increase in utilization of minimally invasive approaches to surgical management of non-metastatic rectal cancer. A robotic approach demonstrated decreased conversion rates than a laparoscopic approach at the rectosigmoid junction and rectum and for LAR and APR. Improved outcomes were seen in the minimally invasive cohorts compared to those that converted to laparotomy.