Radiation lobectomy: Time-dependent analysis of future liver remnant volume in unresectable liver cancer as a bridge to resection

Background & Aims

Portal vein embolization (PVE) is a standard technique for patients not amenable to liver resection due to small future liver remnant ratio (FLR). Radiation lobectomy (RL) with ⁹⁰Y-loaded microspheres (Y90) is hypothesized to induce comparable volumetric changes in liver lobes, while potentially controlling the liver tumor and limiting tumor progression in the untreated lobe. We aimed at testing this concept by performing a comprehensive time-dependent analysis of liver volumes following radioembolization.

Methods

83 patients with right unilobar disease with hepatocellular carcinoma (HCC; N = 67), cholangiocarcinoma (CC; N = 8) or colorectal cancer (CRC; N = 8) were treated by Y90 RL. The total liver volume, lobar (parenchymal) and tumor volumes, FLR and percentage of FLR hypertrophy from baseline (%FLR hypertrophy) were assessed on pre- and post-Y90 CT/MRI scans in a dynamic fashion.

Results

Right lobe atrophy (p = 0.003), left lobe hypertrophy (p <0.001), and FLR hypertrophy (p <0.001) were observed 1 month after Y90 and this was consistent at all follow-up time points. Median %FLR hypertrophy reached 45% (5–186) after 9 months (p <0.001). The median maximal %FLR hypertrophy was 26% (−14→86). Portal vein thrombosis was correlated to %FLR hypertrophy (p = 0.02). Median Child-Pugh score worsening (6→7) was seen at 1 to 3 months (p = 0.03) and 3 to 6 months (p = 0.05) after treatment. Five patients underwent successful right lobectomy (HCC N = 3, CRC N = 1, CC N = 1) and 6 HCCs were transplanted.

Conclusions

Radiation lobectomy by Y90 is a safe and effective technique to hypertrophy the FLR. Volumetric changes are comparable (albeit slightly slower) to PVE while the right lobe tumor is treated synchronously. This novel technique is of particular interest in the bridge-to-resection setting.

Introduction

Portal vein embolization (PVE) is a standard technique for patients with primary or secondary liver malignancies not amenable to liver resection due to small future liver remnant expressed as a percentage ratio of the whole liver volume (FLR). The aim of the procedure is to induce contralateral hypertrophy by redirecting the portal blood flow, thereby leading to an increased ratio of FLR. The range of cut-off ratios of the remnant liver varies from 20% (normal) to 40% (cirrhotic) [1], [2], [3]. However, some authors highlight the limitations of PVE, citing a concern for progression of untreated disease and an increased rate of contralateral metastases while time elapses during the hypertrophy process; this is potentially related to pro-angiogenic factors [4], [5], [6], [7], [8].

Promisingly, radiation lobectomy (RL), defined as the transarterial lobar infusion of ⁹⁰Y-loaded microspheres (Y90), is suspected to induce similar or superior volumetric changes in liver lobes, but potentially offer the concomitant advantage of controlling the liver tumor and limiting tumor progression in the tumor-naïve (and untreated) left lobe by limiting the rate of portal blood flow diversion [9]. This “atrophy-hypertrophy complex” suggests lobar Y90 radioembolization as an alternate procedure to PVE as bridge to liver resection.

The goal of this study was to confirm the changes of embolized and unembolized liver volumes and FLR after lobar radioembolization. Additional goals included assessing long-term sequelae of RL (change in Child-Pugh score), assessing clinical factors predictive of %FLR hypertrophy, control of tumor in the treated lobe, and development of new tumor in the untreated radiation-naïve left lobe.