Spontaneous Regression of Hepatocellular Carcinoma: Three Case Reports and a Categorized Review of the Literature

Excerpt

Hepatocellular carcinoma (HCC) is the most frequent form of primary liver cancer and the fifth most prevalent cancer worldwide [1]. Spontaneous tumor regression was first defined by Cole and Everson [2] as complete or partial clearance of malignant cells in the absence of any specific treatment, particularly antineoplastic chemotherapy. However, it may also occur during or after therapy, a situation in which therapy could be endorsed with an undeserved antitumor effect. Spontaneous tumor regression was at first thought to be an extremely infrequent phenomenon, with an estimated incidence of 1 in 60,000–100,000 cases [3]. Its mechanism is largely unknown, however, it has important implications in clinical research and clinical practice. The number of cases of spontaneous regression reported in the literature is higher in HCC than in other neoplasms [4], possibly reflecting a higher incidence. However, due to its exceedingly low frequency it would probably not affect the results of any study on HCC therapy. Following our observation of two cases of spontaneous regression and one case of sustained, complete regression in the course of a chemotherapeutic regimen with marginal efficacy in the treatment of this tumor, we have searched the cases published in the English literature and reviewed the possible mechanisms involved in such remarkable events. …