A NSQIP Review of Major Morbidity and Mortality of Synchronous Liver Resection for Colorectal Metastasis Stratified by Extent of Liver Resection and Type of Colorectal Resection.

INTRODUCTION: Safety of synchronous hepatectomy and colorectal resection (CRR) for metastatic colorectal cancer remains controversial. We hypothesized that both the extent of hepatectomy and CRR influences postoperative outcomes.
METHODS: Prospective 2005-2013 ACS-NSQIP data were retrospectively reviewed for mortality and major morbidity (MM) after (1) isolated hepatectomy, (2) isolated CRR, and (3) synchronous resection for colorectal cancer. Hepatectomy and CRR risk categories were created based on mortality and MM of respective isolated resections. The synchronous cohort was then stratified based on risk categories. Cumulative asynchronous mortality and MM were estimated compared to that observed in the synchronous cohort via unadjusted relative risk and risk difference.
RESULTS: There were 43,408 patients identified. Among isolated hepatectomy patients (N = 6,661), trisectionectomy and right hepatectomy experienced the greatest mortality and were defined as "major" hepatectomy. Among isolated CRR patients (N = 35,825), diverted left colectomy, abdominoperineal resection, total abdominal colectomy, and total abdominal proctocolectomy experienced the greatest MM and were defined as "high risk" CRR. Synchronous patients (N = 922) were stratified by hepatectomy and CRR risk categories; mortality and MM varied from 0.9 to 5.0 % and 25.5 to 55.0 %, respectively. Mortality and MM were greatest for patients undergoing "high risk" CRR and "major" hepatectomy and lowest for synchronous CRR and "minor" hepatectomy. As both CRR and hepatectomy risk categories increased, there was a significant trend in increasing mortality and MM in synchronous patients. Additionally, comparison of the synchronous resections versus the estimated cumulative asynchronous outcomes showed that (1) mortality was significantly less after synchronous minor hepatectomy and either low or high risk CRR, and (2) neither mortality nor major morbidity differed significantly after major hepatectomy with either high or low risk CRR.
CONCLUSION: Major morbidity after synchronous hepatic and colorectal resections vary incrementally and are related to both the risk of hepatectomy and CRR. Stratification of outcomes by the hepatectomy and CRR components may reflect a more accurate description of risks. Comparison of synchronous and combined outcomes of individual operations supports a potential benefit for synchronous resections with minor hepatectomy.