Hepatic cryosurgery for liver metastases. Long-term follow-up.
The aim of this prospective study was to evaluate the applicability of cryogenic and conventional surgery in treating liver metastases (LM) with respect to intraoperative tumor reduction and survival rate.
                As have been shown in animal experiments as well as in clinical investigations, cryosurgery has been used for the treatment of many benign and malignant conditions. For the first time, this report summarizes a 10-year follow-up clinical experience with cryosurgery for treatment of LM from 1983 to 1992.
                One hundred twenty-three patients with LM (87 males and 36 females, a ratio 2.4:1.0; age, 41.3 +/- 12.1 years) were stratified and entered into a long-term prospective, randomized clinical trial for cryogenic surgery in group 1 (n = 63) and conventional surgical techniques in group 2 (control subjects, n = 60). Principally, a self-constructed cryogenic clamp was used for hepatic cryoresection with preliminary freezing of the margin resection by a cryosurgical system "Cryoelectronic-2" or "Cryoelectronic-4". Hepatic cryoextirpation (cryoablation) and hepatic cryodestruction were performed by means of probes of different roughly disk design from phi 5 mm to 55 mm by volume of frozen zone of 40 cm3 to 180 cm3 for approximately 7 to 32 minutes.
                In most cases in group 1 and group 2, LM were based on colorectal cancers (65% vs. 68%). The hepatic cryosurgical procedures in group 1 included cryoextirpation (29 patients, 46%), cryoresection (20 patients, 32%), and cryodestruction (14 patients, 22%) solely. Clinical and laboratory parameters showed that the curative effects were significantly higher in group 1 than in group 2. The 3-year survival rate was in group 1 and group 2 (60% vs. 51%, respectively). The 5-year survival rate was 44% in group 1 and 36% in group 2. Twelve patients (19%) versus 5 patients (8%) in group 1 and group 2, respectively, survived 10 years. The disease-free survival was in group 1 and group 2 (30% vs. 18%, respectively). During a follow-up period, recurrence in the liver was observed in 54 patients (85%) in group 1 and in 57 patients (95%) in control subjects. After a 10-year follow-up period in group 1 and group 2, 9 patients (14%) versus 3 patients (5%) remained disease free, 3 patients (4%) versus 2 patients (3%) were surviving with disease, and 51 patients (81%) versus 55 patients (92%) died.
                The data of this 10-year prospective, randomized clinical trial suggest that hepatic cryosurgery is effective in the treatment of resectable and nonresectable LM. The results show intraoperative tumor reduction (> or = 90% < or = 97%) and extended higher survival in these patients. The study indicated a 5-year and 10-year survival rate of 44% and 19% after cryosurgery, respectively.
On the basis of one randomised clinical trial with high risk of bias, there is insufficient evidence to conclude if in patients with liver metastases from various primary sites cryotherapy brings any significant benefit in terms of survival or recurrence compared with conventional surgery. In addition, there is no evidence for the effectiveness of cryotherapy when compared with no intervention. At present, cryotherapy cannot be recommended outside randomised clinical trials.