Remnant Liver Ischemia as a Prognostic Factor for Cancer-Specific Survival After Resection of Colorectal Liver Metastases.
IMPORTANCE
Ischemia-reperfusion injury during hepatic resection has been shown to accelerate progression of liver cancer. However, the prognostic relevance of remnant liver ischemia (RLI) after resection of colorectal liver metastases (CLMs) is unknown to date.


OBJECTIVES
To assess the prognostic influence of RLI after resection of CLMs and to identify correlates of greater extent of RLI.


DESIGN, SETTING, AND PARTICIPANTS
This study was a retrospective analysis at The University of Texas MD Anderson Cancer Center based on prospectively collected data. The study identified 202 patients who underwent curative resection of CLMs between January 1, 2008, and December 31, 2014, and had enhanced computed tomographic images obtained within 30 days after surgery.


MAIN OUTCOMES AND MEASURES
Remnant liver ischemia was defined as reduced or absent contrast enhancement during the portal phase. Postoperative RLI was classified as grade 0 (none), 1 (marginal), 2 (partial), 3 (segmental), or 4 (necrotic) as previously defined. Experienced members of the surgical team retrospectively performed imaging assessments. Team members were masked to the postoperative outcomes. Survival after resection was stratified by RLI grade. Predictors of RLI grade 2 or higher and survival were identified.


RESULTS
Among 202 patients (median [range] age, 56 [27-87] years; 84 female), the RLI grades were as follows: grade 0 (105 patients), grade 1 (47 patients), grade 2 (45 patients), grade 3 (5 patients), and grade 4 (0 patients). Recurrence-free survival (RFS) and cancer-specific survival (CSS) rates after hepatic resection were worse in patients with RLI grade 2 or higher vs grade 1 or lower (RFS at 3 years, 6.4% [3 of 50] vs 39.2% [60 of 152]; P < .001 and CSS at 5 years, 20.7% [10 of 50] vs 63.7% [97 of 152]; P < .001). A largest metastasis at least 3 cm (OR, 2.74; 95% CI, 1.35-5.70; P = .005), multiple CLMs (OR, 2.51; 95% CI, 1.25-5.24; P = .009), and nonanatomic resection (odds ratio [OR], 3.29; 95% CI, 1.52-7.63; P = .002) were associated with RLI grade 2 or higher. A largest metastasis at least 3 cm (hazard ratio [HR], 1.70; 95% CI, 1.01-2.88; P = .045), mutant RAS (HR, 2.15; 95% CI, 1.27-3.64; P = .005), and RLI grade 2 or higher (HR, 2.90; 95% CI, 1.69-4.84; P < .001) were associated with worse CSS.


CONCLUSIONS AND RELEVANCE
In this study, remnant liver ischemia grade 2 or higher was associated with worse CSS after resection of CLMs. High-quality anatomic surgery to minimize RLI after resection is essential.