Trends and outcomes of simultaneous versus staged resection of synchronous colorectal cancer and colorectal liver metastases.

Background: The objective of this study was to assess trends in the use as well as the outcomes of patients undergoing simultaneous versus staged resection for synchronous colorectal liver metastases.
Methods: Patients undergoing resection for colorectal liver metastases between 2008 and 2018 were identified using a multi-institutional database. Trends in use and outcomes of simultaneous resection of colorectal liver metastases were examined over time and compared with that of staged resection after propensity score matching.
Results: Among 1,116 patients undergoing resection for colorectal liver metastases, 690 (61.8%) patients had synchronous disease. Among them, 314 (45.5%) patients underwent simultaneous resection, while 376 (54.5%) had staged resection. The proportion of patients undergoing simultaneous resection for synchronous colorectal liver metastases increased over time (2008: 37.2% vs 2018: 47.4%; p _{tre nd}  = 0.02). After propensity score matching (n = 201 per group), patients undergoing simultaneous resection for synchronous colorectal liver metastases had a higher incidence of overall (44.8% vs 34.3%; P = .03) and severe complications (Clavien-Dindo ≥III) (16.9% vs 7.0%; P = .002) yet comparable 90-day mortality (3.5% vs 1.0%; P = .09) compared with patients undergoing staged resection. The incidence of severe morbidity decreased over time (2008: 50% vs 2018: 11.1%; p _{tren d}  = 0.02). Survival was comparable among patients undergoing simultaneous versus staged resection of colorectal liver metastases (3-year overall survival: 66.1% vs 62.3%; P = .67). Following simultaneous resection, severe morbidity and mortality increased incrementally based on the extent of liver resection and complexity of colectomy.
Conclusion: While simultaneous resection was associated with increased morbidity, the incidence of severe morbidity decreased over time. Long-term survival was comparable after simultaneous resection versus staged resection of colorectal liver metastases.
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