Relationship between absorbed dose and changes in liver volume after chemoradiotherapy for esophageal cancer.

Abstract

The liver is the largest organ in the abdomen and is often irradiated in radiotherapy for non-hepatic malignancies. As most of the studies on changes in liver volume are on hepatocellular carcinoma based on liver dysfunction, there are few studies on healthy liver. In this study, we investigated the relationship between absorbed dose and changes in liver volume after chemoradiotherapy for esophageal cancer in patients without apparent pre-treatment liver dysfunction. Liver volume was compared between pre-treatment, acute (< 4months) and late post-treatment (≥ 4 and < 13months) phases in 12 patients using abdominal plain CT images. Volume changes were evaluated separately for the right and left lobes. We investigated the relationship between the volume change and VxGy (percentage of volume received x Gy or more dose). In addition, volume change for each absorbed dose was investigated using deformable image registration. The volume of the left lobe showed a significant decrease between pre-treatment and acute post-treatment phases (p < 0.001), while the volume of right lobe and between acute and late post-treatment phase of left lobe did not. The mean value of the volume reduction rate of the left lobe was 51.1% and equivalent to the mean value of V30Gy. As a result of the volume change for each absorbed dose, the volume reduction rate increased as the absorbed dose increased, and a significant volume loss was observed at doses above 11Gy. Volume of the liver significantly decreased only in the acute phase after chemoradiotherapy for esophageal cancer. The tolerable dose for a healthy liver is generally considered to be 30Gy, but attention should be paid to lower doses to avoid radiation-induced liver injury.