Radiation Therapy in Treating Patients With Liver Cancer That Cannot Be Removed by Surgery

DISEASE CHARACTERISTICS: * Histologically, cytologically, or radiologically confirmed hepatocellular carcinoma * Clinical stage T2-4, N0-1, M0 (stage II, IIIA, IIIB, IIIC) OR unresectable T1, N0-1, M0 (stage I) disease * M1 disease allowed in phase I if at least 90% of the tumor load (volume) is in the liver * Measurable disease (at least one liver lesion that can be measured in at least one dimension as ≥ 10 mm in multislice CT scan/MRI) * Volumetry of liver tumor and residual liver tissue: residual liver volume (= total liver volume - gross tumor volume) has to be ≥ 800 mL and ≥ 40% of total liver volume * No operable disease (with curative intent or planned liver transplantation) * No presence of clinical ascites PATIENT CHARACTERISTICS: * WHO performance status 0-2 * Cirrhosis Child-Pugh class A or B (Child-Pugh score of ≤ 9) * Hemoglobin ≥ 100 g/L * ANC ≥ 1,200/mm³ * Platelet count ≥ 50,000/mm³ * ALT and AST ≤ 7 times upper limit of normal (ULN) * AP ≤ 10 times ULN * Bilirubin ≤ 50 μmol/L * INR ≤ 2 * Creatinine clearance ≥ 50 mL/min * Functional left kidney (scintigraphy mandatory for phase I, phase II only if indicated) * Lipase ≤ 2 times ULN (phase I only) * Able to tolerate proton-pump inhibitors or H2 antagonists during radiation therapy * Not pregnant * Negative pregnancy test * Fertile patients must use effective contraception during and for 4 months after completion of study therapy * No prior malignancy allowed, except for the following: * Adequately treated cervical carcinoma in situ * Adequately treated localized nonmelanoma skin cancer * Any other malignancy from which patient has been disease-free for 5 years * No presence of medically uncontrolled encephalopathy * No myocardial infarction within the past 6 months * No esophageal varices ≥ grade 3, with red signs, or bleeding within the past 3 months * No symptoms of colitis, enteritis, esophagitis, fistula, gastritis, ileus, necrosis, perforation, stricture, or ulcer * No severe anorexia, constipation, dehydration, diarrhea, or vomiting * No serious underlying medical condition that, in the opinion in the investigator, would preclude study participation (e.g., active autoimmune disease or uncontrolled diabetes) * Portal vein thrombosis allowed * No psychiatric disorder precluding understanding of information on study related topics or giving informed consent * No nutritional intake \< 1500 calories per day (corrected) * No weight loss ≥ 15 % within the past 3 months PRIOR CONCURRENT THERAPY: * At least 8 weeks since prior transarterial chemoembolization (TACE), radiofrequency ablation, or radiotherapy (RT) unless progressive disease was documented after this therapy * At least 21 days since prior and no other concurrent treatment with experimental drugs * At least 21 days since prior and no other concurrent treatment on another clinical trial * At least 21 days since prior and no other concurrent anticancer therapy * No prior RT to the abdomen or caudal chest * Prior RT to pelvis allowed * Prior RT to chest must be above D5 vertebra * Portal vein embolization ligation or pre-RT TACE allowed * No concurrent treatment with steroids or non-steroidal anti-inflammatory drugs during RT (proton-pump inhibitor allowed)