Objective To evaluate the use of percutaneous cryosurgery in the treatment of renal tumours.
Materials and methods A cryoprobe using liquid nitrogen was designed. The tolerance of renal cancer cells to cooling was tested. Freezing tests on two extirpated kidneys involved with hypervascular tumour were performed in water at 40d̀C. A clinical trial of percutaneous cryosurgery was carried out in two patients with advanced renal carcinoma.
Results The cooling function of the new probe was similar to that of a conventional probe. The tolerance test on renal cancer cells showed that the cooling temperature should be below — 20d̀C to render them necrotic. Freezing tests on two nephrectomized kidneys with hypervascular renal cancer suggested that embolization of the renal artery might be advisable before treatment. The clinical trial in two patients with advanced renal carcinoma showed that the whole kidney, including the tumour, became necrotic and shrunken post-operatively. The patients' Karnofsky performance scale showed a marked improvement 3 months after the operation, but their general condition gradually deteriorated. Patient 1 died 10 months and patient 2 died 5 months after the procedure.
Conclusion Percutaneous cryosurgery was performed successfully in two patients with hypervascular renal tumours. Cryo-immunological activity was assumed to have contributed to the temporary improvement in their condition. These results suggest that percutaneous cryosurgery might be useful as minimally invasive treatment in a limited number of patients with advanced renal carcinoma.