Survival analysis of patients afflicted with hepatocellular carcinoma undergoing different efficacy treatments

Survival analysis belongs to the longitudinal or follow-up epidemiological studies, in which a predefined population is observed over time to record whether or not the event of interest (e.g. death, birth, onset of disease, recovery, obtaining an academic degree) occurs during the given period. The survival time is the time that elapses from the beginning of the observation up to the event. In this analysis only one event is considered, thus preferring the first to happen in the case of combined events. Initially spread in medical studies, survival analysis has also been applied in different fields ranging from social studies, particularly for duration analysis, to Engineering. The survival time can be defined as the time between the beginning of the study and the event, such as death, the incidence of a cardiovascular event, the time of onset of a pathology, the divorce. In this paper a retrospective analysis it has been performed to evaluate the effects of a experimental therapy administered in a case control-study on patients suffering from hepatocellular carcinoma (from now on, HCC). The 359 patients were enrolled by the medical staff of A.O.U. Policlinico Bari Hospital from 1995 to the first quarter of 2017. HCC is the most frequent neoplasm of the liver. Every year around 70,000 people die of HCC in the world, making it the third cause of death due to carcinoma. Moreover, in some countries, death from HCC is only second to lung cancer. The main risk factors of this disease are hepatitis C virus infection (HCV), hepatitis B virus infection (HBV), even though the latter has been reduced thanks to the vaccination campaigns undertaken for those born since 1978 onwards, abuse of alcohol, which causes liver cancer in 33% of the cases in Northern Italy, aflatoxins taken by food (specially in Eastern Asia and Sub-Saharan Africa), obesity with diabetic complications, tobacco, recently recognized among risk factors. HCC mainly affects males and it is among the first 5 causes of death by cancer only in males (7%) in Italy, according to the Italian National Institute of Statistics (ISTAT). The 5-year survival of patients with liver cancer in Italy is 16.1%, higher than the European average (11.7%). As to the therapy, the treatment strategy for HCC is related to the diffusion degree of the disease and the status of liver function. The Barcelona Clinic Liver Cancer Classification (BCLC) correlated the disease stage with the treatment procedures. In the initial stage, patients with sufficient functioning liver parenchyma may undergo surgical resection and less often at liver transplantation. In the intermediate stages, local ablative treatments with radiofrequency (RF) and chemoembolization through an arterial catheter (TACE) are indicated. In advanced stages of disease, patients with good hepatic function (classified Child A-B) may be treated with Sorafenib, a multichinasic inhibitor. The statistical analysis has been run with two purposes: 1) ascertaining some important literature issues about the inefficacy of the traditional therapy based on Sorafenib, by means of the comparison of the survival curves of treated and not treated patients; 2) investigating whether an innovative therapy developed by the Bari research medical staff and based on the combination of two treatments is more effective in improving patients survival. The results show that a significant increasing in the average survival time has been obtained for patients undergone the combined treatment, depending on patient age and cancer stage