[Swiss study of chemotherapy of alveolar echinococcosis--review of a 20-year clinical research project].

Alveolar echinococcosis (A. E.), caused by Echinococcus multilocularis, behaves biologically like a malignant tumour of the liver which is best treated by radical surgery. However, radical surgery can be performed only in about 20-30% of A. E. cases. The efficacy of chemotherapy with benzimidazole derivatives for inoperable cases is debated. The results of a prospective Swiss chemotherapy trial, which started in 1976, are reviewed. In the last 20 years a total of 110 patients has been included in our protocol and 74 of these patients had inoperable or palliatively operated A. E. (average observation time 12.8 years). The efficacy of long-term chemotherapy was documented by increase of 10-year survival compared to historical (untreated) A. E. cases (80 vs 6%) and by reduction or stabilisation of the liver lesions in 83% of cases during long-term chemotherapy. Several relevant problems remain to be clarified, e.g. optimal duration of chemotherapy, the controversy as to whether chemotherapy is parasitostatic or parasitocidal, the establishment of reliable routine methods for short-term assessment of therapeutic efficacy, and comparative studies between mebendazole and albendazole. Furthermore, additional studies are necessary in collaboration with basic science, for example on the impact of the increasing fox population, with invasion of large agglomerations, on infection risk in the Swiss population, and the importance of individual immune competence for susceptibility or resistance to A. E.