DISEASE CHARACTERISTICS: Histologically confirmed primary colorectal adenocarcinoma with synchronous and metachronous metastases to liver 1 to 5 liver metastases demonstrated by rapid sequence CT scan or Feridex-enhanced MRI within 2 weeks of registration CT portography not required No single metastasis greater than 6 cm Maximum liver involvement must not be more than 40% by volume No extrahepatic metastases