The lethal and enduring inequity of deceased donor liver allocation policy for hepatocellular carcinoma in the United States

Proposal of a novel MELD exception point system for hepatocellular carcinoma based on tumor characteristics and dynamics

BACKGROUND & AIMS

Patients listed with exception points for hepatocellular carcinoma (HCC) have been more likely to be transplanted than those listed for chronic liver failure (LF) based on the model for end-stage liver disease (MELD) score. The aim of this study was to determine outcomes in the 5-year experience of a scoring system designed to reflect heterogeneity of tumor load of patients listed for HCC.

METHODS

A novel MELD exception point system based on size and number of HCC was implemented in July 2009. This system allows stratification of patients based on risk of dropping out from the waiting list according to Milan criteria. LF patients were listed according to biological MELD sodium score; HCC patients were reassigned points every three months upon repeat imaging.

RESULTS

Among 624 patients listed for liver transplant (LT), 505 were eligible. 94 (18.6%) were assigned MELD HCC points. Only 24.7% required changes in allocated points over time. Transplantation rates (HCC 83% vs. LF 73%, p=0.04) and waiting time in days (HCC 258 vs. LF 325; p=0.07) were similar. The method of competing risk analysis revealed that HCC patients were more likely to be transplanted than LF during the 5-year period preceding implementation, whereas transplant rates became equivalent for HCC and non-HCC in 2009-2014. One- and two-year survivals were similar between the two groups.

CONCLUSIONS

Our study demonstrates that a novel MELD point system for HCC, taking into account dynamics in tumor size and number, allows for equitable liver allocation without compromising graft and patient survival.

LAY SUMMARY

It has historically been difficult to achieve equitable liver allocation for liver cancer and chronic liver failure with the allocation systems currently in place in many countries worldwide. We designed a new system to help improve access to organs for liver failure patients in Québec, Canada. Our 5-year experience demonstrates that this unique system renders access to transplant similar for both liver cancer and liver failure indications.

Comparison of Liver Transplant-Related Survival Benefit in Patients With Versus Without Hepatocellular Carcinoma in the United States

BACKGROUND & AIMS

Patients with T2 hepatocellular carcinoma (HCC) can obtain an exception that allows them to undergo liver transplantation with much lower actual Model for End-Stage Liver Disease (MELD) scores than patients without HCC. We compared patients who received liver transplants, with and without HCC, with regard to transplantation-related survival benefit.

METHODS

We modeled the post-transplantation survival of adult, first-time liver transplant recipients with HCC (n = 9135) or without (n = 25,890) from 2002 through 2013 using Cox proportional hazards regression. We modeled waitlist survival of patients listed for transplantation with HCC (n = 15,605) or without (n = 85,229) using competing risks analysis and combined outcomes of death or liver failure (defined as MELD score ≥30). We used these survival models to calculate monthly transition probabilities and 5-year life expectancies. Survival benefit was calculated as the difference between post-transplantation and waitlist life expectancy.

RESULTS

The 5-year survival benefit increased with actual MELD score for patients with and without HCC, ranging from just a few months in patients with low MELD scores (ie, 6-8) to 4 years in patients with the highest MELD scores (ie, 36-40). The survival benefit of patients with HCC was similar to that of patients without HCC who had the same actual MELD score, irrespective of tumor burden or serum level of α-fetoprotein. However, because patients with HCC received liver transplants when they had a lower mean MELD score (13.3 ± 6.2) than patients without HCC (21.8 ± 8.0), a much lower mean 5-year survival benefit was achieved by providing liver transplants to patients with HCC (0.12 years/patient) than patients without HCC (1.47 years/patient).

CONCLUSIONS

The HCC MELD exception policy has unintentionally resulted in a large reduction in transplantation-related survival benefit.

Excess mortality on the liver transplant waiting list: unintended policy consequences and Model for End-Stage Liver Disease (MELD) inflation

The Model for End-Stage Liver Disease (MELD) allocation system for liver transplantation provides "exceptions" for diseases such as hepatocellular carcinoma (HCC). It was the aim of this study to assess equipoise between exception candidates and nonexception candidates on the waiting list and to assess if the exception system contributes to steadily increasing regional MELD at transplant. In all, 78,595 adult liver transplant candidates between January 2005 and December 2012 were analyzed. Yearly trends in waiting list characteristics and transplantation rates were analyzed for statistical association with MELD exceptions. Regional variations in these associations and the effect of exceptions on regional MELD scores at transplant were also analyzed. 27.29% of the waiting list was occupied by candidates with exceptions. Candidates with exceptions fared much better on the waiting list compared to those without exceptions in mean days waiting (HCC 237 versus non-HCC 426), transplantation rates (HCC 79.05% versus non-HCC 40.60%), and waiting list death rates (HCC 4.49% versus non-HCC 24.63%). Strong regional variation in exception use occurred but exceptions were highly correlated with waiting list death rates, transplantation rates, and MELD score at removal in all regions. In a multivariate model predicting MELD score at transplant within regions, the percentage of HCC MELD exceptions was the strongest independent predictor of regional MELD score at transplant.

CONCLUSION

Liver transplant candidates with MELD exceptions have superior outcomes compared to nonexception candidates and the current MELD exception system is largely responsible for steadily increasing MELD scores at transplant independent of geography.

Evolving trends in liver transplantation: listing and liver donor allocation

The success of liver transplantation in the past three decades as a life-saving procedure for patients with end-stage liver disease has led to the ever-increasing disparity between the demands for liver transplantation and the supply of donor liver organs. Donor allocation and distribution remains a challenge and a moral issue as to how these organs can be equitably distributed. This article reviews the evolution of the liver allocation policy and discusses in detail the challenges clinicians face today in this area of medicine.

Waiting time and explant pathology in transplant recipients with hepatocellular carcinoma: a novel study using national data

Risk factors for hepatocellular carcinoma (HCC) recurrence after liver transplantation have been well described. It has been surmised that longer time on the waitlist may select for tumors with a lower-risk of recurrence posttransplant, as patients with unfavorable tumor characteristics would be delisted due to tumor progression. Utilizing national explant pathology records from transplant recipients waitlisted with T2 HCC exception points, this study explored the correlation between waiting time and the development of pathologic HCC features associated with increased risk of tumor recurrence. Of 1976 explant pathology reports submitted nationally between April 8, 2012 and June 30, 2013, 1453 (73.5%) were from recipients with automatic T2 HCC exception points. There was no association between pretransplant waiting time and the proportion of HCC explants with either: (i) a poorly differentiated tumor; (ii) macrovascular invasion; (iii) HCC beyond Milan or University of California San Francisco criteria; (iv) HCC beyond the "up-to-seven" criteria; or (v) extra-hepatic or lymph node involvement. Though there was a statistically significant increase in microvascular invasion in recipients with pretransplant waiting 6-12 months, this association was not seen when adjusted for United Network for Organ Sharing region. These findings suggest that waiting time alone may not select for tumors with more favorable characteristics.