Parenchyma-Sparing Hepatectomy or Major Hepatectomy for Colorectal Liver Metastases?

In 2012, we previously reported that nonanatomic hepatectomy with narrow margins is the optimal treatment strategy for colorectal liver metastases (CLM). 1 Since then, the concept of parenchymasparing hepatectomy (PSH) has become popular,2, 3 and studies have demonstrated that compared with major hepatectomy (MH), PSH has more favorable short-term outcomes and also allows for the treatment of remnant liver recurrence if sufficient liver volume is conserved. However, the use of PSH for CLM remains controversial because the surgical margins are close to the tumors, and the residual parenchyma has a high risk of future liver metastases. Therefore, in the present study, we used threedimensional (3D) image processing technology to measure operative results, remnant liver regeneration, and short-term and long-term outcomes based on propensity score matching (PSM) by procedure (PSH vs MH). Between April 4, 2001, and December 21, 2015, 272 consecutive patients who underwent initial hepatectomy for CLM at Osaka Medical College Hospital were retrospectively analyzed using PSM analysis. All patients were fully informed of the study design according to the Ethics Committee on Clinical Investigation of Osaka Medical College Hospital (No. 2001 and 2059) and provided written informed consent. Four hepatobiliary surgeons with expertise in performing abdominal CT (YI, FH, and KU) traced the contours of the total liver. The manufacturer’s software (Synapse Vincent, Fujifilm, Tokyo, Japan) automatically calculated the number of pixels within the traced contours in each section and provided a cross-sectional area of the liver on a section-bysection basis. The circumscribed areas were then automatically multiplied by the CT section thickness, yielding an approximate volume for total liver, and total liver volume (TLV) were summed. On preoperative CT scans, we measured TLV and the remnant segmental volumes. The liver remnant volume was postoperatively measured with MDCT on postoperative day seven and postoperative months 1, 2, 5, 12, and 24. From these data, we calculated the following ratios: 1) the remnant liver volume (RLV), calculated as (TLV + tumor volume) – resected liver volume and (b) the regeneration rate, calculated as (RLV at day seven and months 1, 2, 5, 12, and 24/TLV) · 100. Patients were enrolled between April 2001 to December 2015 and divided into two groups: PSH (n4 215) and MH (n4 57). To avoid selection bias, we performed a 1:1 correspondence comparison using PSM and selected 60 patients who received either PSH or MH into the final study. The results of the assessment of RLV regeneration are shown in Table 1. After PSM, RLV was significantly larger immediately after operative treatment in the PSH group (P# 0.001), as well as at one week and months 1, 2, 5, and 12 postoperatively (P 4 0.034, 0.043, 0.027, 0.005, and 0.049, respectively). In both groups, RLV enlarged rapidly until seven days postoperatively but reduced over the subsequent one to two postoperative months. Two months postoperatively, we noted a progressive regeneration of the RLV, which eventually approximated its original capacity after 24 months. Analysis of changes in total bilirubin (T-Bil), albumin (Alb), prothrombin time (PT), and platelet (Plt) levels at 1, 2, 4, 7, and 14 days and 1, 2, 5, and 12 months postoperatively revealed that T-Bil levels on postoperative days one and two were significantly higher in the MH group, but this difference was not sustained throughout the follow-up period. In fact, Address correspondence and reprint requests to Yoshihiro Inoue, M.D, Department of General and Gastroenterological Surgery, Osaka Medical College Hospital, 2-7 Daigaku-machi, Takatsuki City, Osaka 569-8686, Japan. E-mail: sur129@osaka-med. ac.jp.