The Intention-to-treat Effect of Bridge Therapies in the Setting of Milan-in Patients

Liver transplantation (LT) is the best curative treatment of hepatocellular cancer (HCC) developed in an underlying liver disease. LT is considered as an oncologic successful procedure when a long-term post-transplant tumour-free survival is obtained. Conversely, a failure is equal to pre-transplant drop-out, post-transplant tumour recurrence or death. Due to the allograft scarcity, a HCC patient waiting for a LT is most often treated using neo-adjuvant loco-regional therapies (LRT) in order to minimise the risk of drop-out. When the tumour burden meets the Milan Criteria (MC) at moment of diagnosis, such an approach is called "bridging towards LT".

Two recent international guidelines underlined the importance of the bridging strategy, due to its potential to reduce the risk of pre-LT drop-out and post-LT recurrence. This is especially valid in the case in which a partial/complete tumour response is achieved before LT. Unfortunately, the quality of the evidence obtained from the currently available literature is low due to the lack of randomized controlled trials (RCT). Actually, it is inconceivable to realize RCT in this setting because of logistical and, even more, ethical reasons. Consequently, the majority of reported studies just compare post-LT outcome of treated and untreated patients, failing thereby to analyse the clinical course from an intention-to-treat (ITT) point of view.

Even when looking at studies including the waiting list period, one should keep in mind that substantial differences may exist among initially bridged vs untreated HCC patients regarding tumour burden. In order to overcome these limits, a retrospective analysis of a large European population of MC-IN HCC patients listed for LT was done. After "balancing" this cohort with an inverse probability of treatment weighting (IPTW), we investigated the risk factors for tumour-specific LT failure, especially focusing at the role of LRT.