Changes of standardized uptake value in 18F-FDG positron emission tomography after recurrence of hepatocellular carcinoma in patients with sirolimus in living donor liver transplantation

Sirolimus is known to have both an immunosuppressive effect and also an anticancer effect. The standardized uptake value(SUV) of 18F-FDG positron emission tomography(18F-FDG PET) reflects tumor cell viability in not only hepatocellular carcinoma(HCC)but also in other cancers. We hypothesized that sirolimus could reduce the SUV compared to the calcineurine inhibitor(CNI)group after HCC recurrence in living donor liver transplantation(LDLT). We retrospectively reviewed 532 patients who underwent LDLT for HCC. Among them 92 patients(17.3%) experienced recurrence and 47 patients underwent 18F-FDG PET before LDLT and after recurrence. We measured the maximum value of SUV in the tumor(SUV-Tmax)before transplantation and compared to the recurrence site of that after recurrence. The repeated-measure-ANOVA was used to compare the patient group who used only CNI and those who used CNI and sirolimus together(S-CNI). A total of 25 patients were included in the CNIgroup and 22 patients were included in the S-CNIgroup. There was no difference in the age and sex, recurrence site, and time to recurrence(11±9 vs. 10±8, p=0.56) However the S-CNI group had more aggressive tumor features such as following; microscopic vascular invasion, beyond Milan, and SUV-Tmax before LDLT(6.13 ± 3.38 vs. 4.02 ± 2.52, p=0.019). In the repeated ANOVA analysis, the SUV-Tmax was significantly more decreased in the S-CNI group than the CNI group(F=6.022, p=0.018). In patients with early recurrence less than 1year, SUV-Tmax was more decreased in the S-CNI group than the CNI group(F=6.113, p=0.02). Sirolimus has an impact on reducing the SUV-Tmax after HCC recurrence based on comparison of the maximum value of the original tumor before LDLT.