Unquestionably, progress has been made in the early detection and early treatment of primary liver cancers (PLCs), although most remain unresectable, mainly because the cancer is advanced and coexists with liver cirrhosis, particularly in Oriental patients. Thanks to the progress of regional cancer therapy, a multidisciplinary approach, and changing concepts about surgical oncology, it has been proved that some unresectable but not far advanced PLCs are potentially convertible to being resectable, particularly those cancers confined to the right lobe of a cirrhotic liver. A retrospective analysis of 571 unresectable PLCs revealed the following: (1) There was an increase in 5-year survivals in the series, from 0% during the 1960s (n = 61), to 4.8% during the 1970s (n = 163), to 21.2% during the 1980s (n = 347). It might be a result of the increase in double- or triple-modality treatments in these series (from 9.8%, to 19.6%, to 70.3%, respectively) and in the sequential resection rate after cytoreduction (from 0%, to 2.5%, to 14.7%). (2) The combination of hepatic artery ligation, hepatic artery cannulation and infusion, and intrahepatic arterial radioimmunotherapy has resulted in better shrinkage of the tumor, a higher sequential resection rate, and a higher 5-year survival (28.2%). (3) Of the 55 patients who had initially unresectable PLCs and yielded "cytoreduction and sequential resection," the 5-year survival was 58.5%. It is concluded that cytoreduction and sequential resection might be an important approach to improving the prognosis of patients with unresectable PLCs.