This study was designed to test the hypothesis that vasodilator drugs can enhance selective heating of solid tumors by producing a favorable redistribution of blood flow between tumor and normal tissues. Subcutaneous transmissible venereal tumor implants were heated by inductive diathermy using Helmholtz coils in 8 dogs. The temperature rise in tumor and adjacent muscle was measured before and after giving hydralazine (0.5 mg/kg i.v.). Blood flow to the tumors and underlying muscle was measured with radioactive tracer microspheres. Before hydralazine treatment mean muscle blood flow was about one-third tumor blood flow (0.11  0.02 vs. 0.28  0.09 ml/min/g), and tumor and normal muscle temperatures were not significantly different (40.0  0.6 vs. 39.7  0.l oC). After hydralazine tumor blood flow decreased and muscle blood flow increased in every dog, and selective heating of the tumors became possible. Muscle blood flow averaged 0.67  0.13 ml/min/g, 17 times greater than tumor blood flow, which decreased to 0.04 0.02 ml/min/g. Core tumor temperature was 48.0  0.9 vs. 38.5  0.5 oC for underlying muscle. Blood pressure was maintained at 80  5.7 mmHg. These results demonstrate that adjuvant treatment with vasodilators is a promising technique to increase the temperature difference between tumors and surrounding normal tissues during local heat therapy.


This is the author accepted manuscript of Voorhees W.D., Babbs C.F., Hydralazine-enhanced heating of transmissible venereal tumor implants in dogs, European Journal of Cancer & Clinical Oncology 18, 1027-1034, 1982. Copyright Elsevier, it is made available here CC-BY-NC-ND, and the version of record is available at https://doi.org/10.1016/0277-5379(82)90252-8.


blood flow, heat, hyperthermia, regression, therapeutic ratio, treatment, tumor

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