Experimental and clinical observations on hepatic cryosurgery for colorectal metastases.

Cryosurgery, using liquid nitrogen at -196 degrees C, was explored for treating colorectal liver metastases in an experimental study of rat colon cancer and in a clinical investigation of patients with unresectable liver tumors. The viability of rat colon cancer isografts showed that while two or three freeze-thaw cycles were 100% effective in controlling established isografts and preventing isograft take, one freeze-thaw cycle was suboptimal. In these animals cryosurgery was as effective as surgical resection in controlling established experimental liver metastases. Cryosurgery by operative liver exposure and intraoperative ultrasound monitoring were used to treat liver metastases from colorectal cancer in 24 patients. At a median follow-up of 2 years (range, 5 months to 5 years), seven patients (29%) are disease free, eight (33.5%) are alive with recurrent tumors, and nine (37.5%) have died. The patterns of failure were: remaining liver and extrahepatic sites, ten patients (59%); remaining liver only, six patients (35%); and extrahepatic only, one patient (6%). These data demonstrate that cryosurgery is a useful modality for treating unresectable primary and metastatic liver cancers. Addition of systemic adjuvant therapy may improve the tertiary failure following the control of liver metastases.