The combined effects of shock waves and cisplatin therapy on rat prostate tumors

The effects of focused high energy shock waves (SW) generated by the Dornier experimental XL-1 lithotripter alone or in combination with cisplatin (CDDP) on the AT-2 prostate tumor were examined. They were assessed by measuring 1) clonogenic cell survival 24 hours after treatment, 2) tumor growth delay, and 3) the number of lung metastases. The survival of clonogenic cells was reduced 38% by exposure to 2000 SW and tumor growth was delayed by 1.5 days. The limb bearing the tumor was excised in all animals when the tumor reached seven cm.3 The subsequent occurrence of lung metastases in three out of 13 unshocked animals and two out of 14 shocked animals indicated that SW did not promote the dissemination of tumor cells. At doses of one to four mg. CDDP/kg. body weight, SW exposure increased the effectiveness of the chemotherapy measured by a clonogenic assay. The fractional survival was 0.62 after 2000 SW alone, 0.23 with four mg. cisplatin/kg. alone and 0.10 after the combination treatment. At higher doses of CDDP, there was no added effect of SW over that of CDDP therapy alone. Tumor growth to one cm.3 was delayed by seven days after treatment with four mg. CDDP/kg., in comparison to untreated controls. SW exposure combined with CDDP treatment delayed the time taken for the tumor to reach one cm.3 by 13 days in comparison with untreated controls. However, the combination treatment increased animal mortality from 9% with CDDP alone to 29%. These results indicate that SW could be used focally to enhance the cell killing effects of CDDP.