Enhancement by misonidazole of metastatic tumor nodule formation in the lungs of mice

Radiation enhancement of metastasis: a review

Virtually every modality employed in the treatment of cancer has demonstrated an adverse effect upon metastasis under some conditions. This review surveys the experimental and clinical literature pertaining to the untoward effects of ionizing radiation upon metastatic processes. Two processes are described: (1) enhancement of metastases following local tumor irradiation; (2) localization of metastasis in previously irradiated normal tissues. In the first process the experimental evidence indicates a local effect of irradiation upon the tumor-stroma interface. It predominates under conditions of non-curative radiation doses. There is no proof that this process occurs in clinical practice, but a review of data provides suggestive evidence for its existence following non-curative therapy. The second process is documented both experimentally and clinically. It requires the presence of viable, circulating tumor cells and appears mediated through vascular damage. The few clinical reports suggest that this effect is rare in practice. The clinical significance of both processes appears small under conditions of effective tumor therapy, but it is speculated that inadequate tumor irradiation, or irradiation of normal tissues with uncontrolled tumor elsewhere, may be deleterious.

Influence of misonidazole, SR-2508, RSU-1069 and WR-2721 on spontaneous metastases in C57BL mice

The effect of treatments with the hypoxic cell radiosensitizers misonidazole (MISO), SR-2508, RSU-1069, and with the radioprotector WR-2721 on spontaneously disseminated Lewis lung carcinoma (LLC) and B16 melanoma (B16M) was investigated. Tumors were implanted into the tails of C57BL mice and were surgically removed after reaching volumes of approximately 40 mm3. This technique results in the induction of metastatic disease in lungs and at other anatomical sites and allows the independent treatment of disseminated tumor cells. The radiosensitizers and the radioprotector were administered 24 hr after surgery and animals were killed 14 and 30 days after removal of LLC and B16M, respectively. The time to death from spontaneous metastases was also measured. Both single treatments with large doses of MISO (1.0 g/kg) and fractionated therapy with smaller doses (0.5 g/kg on 5 consecutive days) promoted the formation of metastases to the lungs, lymph nodes and other organs. The survival times of MISO treated animals did not differ from control animals but manifestation of metastatic disease in the lungs and other organs occurred at earlier times. Administration of equitoxic doses of SR-2508 (3.0 g/kg) and RSU-1069 (0.1 g/kg) also promoted metastases formation. Mice treated with these radiosensitizers developed more metastases in the lungs and at other sites. Treatment with a single dose of WR-2721 (0.4 g/kg) promoted lung metastases but exerted a suppressive effect on lymph node tumors. When the radioprotector was given in fractionated schedules in three different doses (0.05 g/kg, 0.1 g/kg and 0.2 g/kg for 10 consecutive days) a slight enhancement of lung metastases and suppression of extrapulmonary metastases was observed.

Effect of the radiosensitizer misonidazole and the radioprotector diethyldithiocarbamate on spontaneous metastasis formation of murine tumors

The effect of treatment with the hypoxic cell radiosensitizer misonidazole (MISO) and the radioprotector diethyldithiocarbamate (DDC) on the formation of spontaneous lung metastases of four different spontaneously metastasizing murine tumors was investigated. The tumors were mammary carcinoma MCA-K, hepatocarcinoma HCA-1, and sarcomas SA-4020 and SA-NH. Multiple daily treatments with MISO significantly enhanced the incidence of metastases only in MCA-K. Because only MCA-K, but not the three remaining tumors, is immunogenic, the treatment with MISO may be associated with the promotion of metastasis primarily in the immunogenic tumors. Treatment of mice with DDC had no influence on metastatic spread. However, when given prior to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), DDC reduced BCNU-induced enhancement of HCA-1 metastases.

Effect of a perfluorochemical emulsion on the development of artificial lung metastases in mice

Intravenous infusions of perfluorochemical emulsions, combined with administration of inspired oxygen or carbogen have been found to improve tumor oxygenation and increase the response of solid tumors in animals to radiotherapy. Fluosol-DA 20 per cent, the only perfluorochemical emulsion currently approved for testing in humans in the United States, has recently entered clinical trials as an adjunct to radiotherapy in the treatment of head and neck carcinoma. The studies reported here were undertaken as part of our laboratory evaluation of the safety and clinical potential of this oxygen-transport fluid as an adjunct to cancer therapy; they asked whether single or multiple treatments with Fluosol and an oxygen-enriched atmosphere produced immunologic perturbations, pulmonary damage, or other effects which altered the development of artificial lung metastases in experimental animals. Neither single nor multiple treatments with clinically relevant regimens of Fluosol and carbogen (95 per cent O2/5 per cent CO2) had any effect on the development of lung nodules from intravenously injected EMT6 tumor cells.

Enhancement of artificial lung metastases by misonidazole

The effect of treatment with the hypoxic cell radiosensitizer misonidazole on the formation of artificial lung metastases was examined. Both single treatments with large doses of misonidazole and fractionated treatments with smaller doses of misonidazole were found to increase the number of lung tumors developing after intravenous injection of EMT6 mouse mammary carcinoma cells. The immunologic and physiologic effects of the nitroimidazole were postulated to be responsible for the enhancement of lung tumor formation.