Parenchymal-sparing hepatectomy for colorectal liver metastases reduces postoperative morbidity while maintaining equivalent oncologic outcomes compared to non-parenchymal-sparing resection

Background: Modern chemotherapy and repeat hepatectomy allow to tailor the surgical strategies for the treatment of colorectal liver metastases (CRLM). This study addresses the hypothesis that parenchymal-sparing hepatectomy reduces postoperative complications while ensuring similar oncologic outcomes compared to the standardized non-parenchymal-sparing procedures. Methods: Clinicopathological data of patients who underwent liver resection for CRLM between 2012 and 2019 at a hepatobiliary center in Switzerland were assessed. Patients were stratified according to the tumor burden score [TBS2 = (maximum tumor diameter in cm)(2) + (number of lesions)(2))] and were dichotomized in a lower and a higher tumor burden cohort according to the median TBS. Postoperative outcomes, overall survival (OS) and recurrence-free survival (RFS) of patients following parenchymal-sparing resection (PSR) for CRLM were compared with those of patients undergoing non-PSR. Results: During the study period, 153 patients underwent liver resection for CRLM with curative intent. PSR was performed in 79 patients with TBS <4.5, and in 42 patients with TBS >= 4.5. Perioperative chemotherapy was administered in equal rates in both groups (PSR vs. non-PSR) both in TBS >= 4.5 and TBS <4.5. In patients with lower tumor burden (TBS <4.5), PSR was associated with lower overall complication rate (15.2% vs. 46.2%, p = 0.009), a trend for lower major complication rate (8.9% vs. 23.1%, p = 0.123), and shorter length of hospital stay (5 vs. 9 days, p = 0.006) in comparison to non-PSR. For TBS >= 4.5, PSR resulted in equivalent 5-year OS (48% vs. 39%, p = 0.479) and equivalent 5-year RFS rates (44% vs. 29%, p = 0.184) compared to non-PSR. For TBS >4.5, PSR resulted in lower postoperative complication rate (33.3% vs. 63.2%, p = 0.031), a trend for lower major complication rate (23.8% vs. 42.2%, p = 0.150), lower length of hospital stay (6 vs. 9 days, p = 0.005), equivalent 5-year OS (29% vs. 22%, p = 0.314), and equivalent 5-year RFS rates (29% vs. 18%, p = 0.156) compared to non-PSR. Among all patients treated with PSR, patients undergoing minimal-invasive hepatectomy had equivalent 5-year OS (42% vs. 37%, p = 0.261) and equivalent 5-year RFS (34% vs. 34%, p = 0.613) rates compared to patients undergoing open hepatectomy. Conclusions: PSR for CRLM is associated with lower postoperative morbidity, shorter length of hospital stay, and equivalent oncologic outcomes compared to non-PSR, independently of tumor burden. Our findings suggest that minimal-invasive PSR should be considered as the preferred method for the treatment of curatively resectable CRLM, if allowed by tumor size and location.