The use of bridging locoregional therapy (LRT) before liver transplantation in patients with hepatocellular carcinoma (HCC) has significantly increased in the United States within the past 15 years, a recent analysis suggests. Data show that liver transplant candidates with HCC who have elevated tumor burden and patients with more compensated liver disease have received a greater number of treatments while awaiting transplant.
According to the researchers, led by Allison Kwong, MD, of Stanford (Calif.) University, liver transplant remains a curative option for individuals with unresectable HCC who meet prespecified size criteria. In the United States, a mandated waiting period of 6 months prior “to gaining exception points has been implemented” in an effort “to allow for consideration of tumor biology and reduce the disparities in waitlist dropout between HCC and non-HCC patients,” the researchers wrote.
Several forms of LRT are now available for HCC, including chemoembolization, external beam radiation, radioembolization, and radiofrequency or microwave ablation. In the liver transplant setting, these LRT options enable management of intrahepatic disease in patients who are waiting for liver transplant, Dr. Kwong and colleagues explained.
The researchers, who published their study findings online August 3 in, sought to examine the national temporal trends and waitlist outcomes of LRT in 31,609 patients eligible for liver transplant with greater than or equal to 1 approved HCC exception application in the United States.
Patient data were obtained from the Organ Procurement and Transplantation Network database and comprised primary adult LT candidates who were listed from the years 2003 to 2018. The investigators assessed explant histology and performed multivariable competing risk analysis to examine the relationship between the type of first LRT and time to waitlist dropout.
The waitlist dropout variable was defined by list removal due to death or excessive illness. The researchers noted that list removal likely represents disease progression “beyond transplantable criteria and beyond which patients were unlikely to benefit from or be eligible for further LRT.”
In the study population, the median age was 59 years, and approximately 77% of patients were male. More than half (53.1%) of the cohort had hepatitis C as the predominant liver disease etiology. Patients had a median follow-up period of 214 days on the waitlist.
Most patients (79%) received deceased or living-donor transplants, and 18.6% of patients were removed from the waitlist. Between the 2003 and 2006 period, the median waitlist time was 123 days, but this median waitlist duration increased to 257 days for patients listed between 2015 and 2018.
A total of 34,610 LRTs were performed among 24,145 liver transplant candidates during the study period. From 2003 to 2018, the proportion of patients with greater than or equal to 1 LRT recorded in the database rose from 42.3% to 92.4%, respectively. Most patients (67.8%) who received liver-directed therapy had a single LRT, while 23.8% of patients had 2 LRTs, 6.2% had 3 LRTs, and 2.2% had greater than or equal to 4 LRTs.
The most frequent type of LRT performed was chemoembolization, followed by thermal ablation. Radioembolization increased from less than 5% in 2013 to 19% in 2018. Moreover, in 2018, chemoembolization accounted for 50% of LRTs, while thermal ablation accounted for 22% of LRTs.
The incidence rates of LRT per 100 waitlist days was above average in patients who had an initial tumor burden beyond the Milan criteria (0.188), an alpha-fetoprotein level of 21-40 (0.171) or 41-500 ng/mL (0.179), Child-Pugh class A (0.160), patients in short (0.151) and medium (0.154) wait-time regions, as well as patients who were listed following implementation of cap-and-delay in October 2015 (0.192).
In the multivariable competing-risk analysis for waitlist dropout, adjusting for initial tumor burden and AFP, Child-Pugh class, wait region, and listing era, no locoregional therapy was associated with an increased risk of waitlist dropout versus chemoembolization as the first LRT in a multivariable competing-risk analysis (subhazard ratio [sHR], 1.37; 95% CI, 1.28-1.47). The inverse probability of treatment weighting–adjusted analysis found an association between radioembolization, when compared with chemoembolization, and a reduced risk of waitlist dropout (sHR, 0.85; 95% CI, 0.81-0.89). Thermal ablation was also associated with a reduced risk of waitlist dropout, compared with chemoembolization (sHR, 0.95; 95% CI, 0.91-0.99). “Radioembolization and thermal ablation may be superior to chemoembolization and prove to be more cost-effective options, depending on the clinical context,” the researchers wrote.
The researchers noted that they were unable to distinguish patients who were removed from the waitlist between those with disease progression versus liver failure.
The researchers reported no conflicts of interest with the pharmaceutical industry. The study received no industry funding.