Metachronous liver metastasis of colorectal cancer: timing of occurrence and efficacy of adjuvant portal chemotherapy.

We estimated the time of occurrence of metachronous liver metastasis in colorectal cancer patients from tumor diameter and doubling time. Micro-metastasis was present prior to operation in most patients and a few metastatic cases could have been initiated by the surgical procedure. Portal chemotherapy is more effective against liver metastasis than intravenous infusion because a higher drug concentration in the liver can be obtained. This efficacy of portal chemotherapy on survival was also observed in a rat model. Thus perioperative adjuvant treatment should be undertaken for metastasis which already existed before the operation and adjuvant chemotherapy via portal vein is the treatment of choice. The no touch isolation technique is also needed to avoid spreading of tumor cells during surgery.