ESPITE great advances in medicine, the re-D sults of treatment of malignant tumors remains unsatisfactory. Development of chemotherapy of inoperable malignant tumors is still in a beginning state. T h e high mortality rate resulting from secondary growth-recurrence and metastases-in patients having had radical operations is most likely due to the fact that micrometastases are present in different organs at the time of operation: furthermore cancer cells or strands of cells from the primary tumor are being disseminated into the blood stream spontaneously, particularly, however, during surgery.
Surgery and radiotherapy are only locally effective; therefore the idea arose to combine surgical treatment with chemotherapy as a general therapeutic measure, in order to destroy circulating cancer cells and micrometastases remaining in the body after operation.
Based on their experiments with tumor implants in rats, Druckrey24, 25 and Druckrey and associates,26 and Lo55 recommended combined surgical and chemotherapeutic treatment. Unaware of this work, we started a series of experiments in 1955 in order to find out if the mortality rate due to secondary growth following radical operation could be decreased by means of postoperative chemotherapy. Results of these experiments have been published elsewhere.13, 14, 42-46 At first a series of experiments was performed on 4,000 rats and 1,250 mice imitating the invasion of tumor cells into the blood stream and its consequences in human patients. We injected 1 to 2 million cells of reticulum cell-like sarcoma Yoshida, carcinosarcoma 256 Walker, or ascites tumor Ehrlich into the tail vein, obtaining tumor growth in 80 to l O O ~& T h e animals died in 10 to 20
From the Austrian Cancer Research Institute, Vienna, Austria.
We wish to express our thanks for the co-operation and kindness of the physicians and the hospitals in and around Vienna participating in the study.