The goal of this national mutlticenter observational study is to learn and describe trends over time in the use of techniques for inducing hepatic hypertrophy in Italy. Patients will be treated according to the current clinical practice of the participating centers and will be observed from the moment of recruitment and throughout their stay. Information on vital status will be collected, as far as possible, for up to 5 years after surgery in order to record any events that occur in a timely manner. There are also plans to retrospectively collect data on patients who underwent hypertrophic techniques in the previous 10 years, in order to establish a historical cohort for each center that can be used for comparison with the prospective cohort.