RADIONUCLIDE THERAPY OF SKIN CANCERS AND BOWENS-DISEASE USING A SPECIALLY DESIGNED SKIN PATCH

Skin cancer is the most common malignancy in humans. Therapeutic modal ities for skin cancer are local destruction, radiotherapy and surgery. External radiation therapy leads to good results, however, generally 5-6 wk of treatment is needed to deliver optimal radiation dose to tum ors. In this study, a beta-emitting radionuclide, Ho-166, impregnated in a specially designed patch, was used on superficial skin cancers an d Bowen's disease for local irradiation. Methods: Ten mice with chemic ally induced skin tumors were studied. Five-millimeter size patches co ntaining 22.2-72.15 MBq (0.6-1.95 mCi) Ho-166 were applied to the tumo r surface for 1-2 hr. In a human trial, patients with squamous-cell ca rcinoma (n = 3), basal cell carcinoma (n = 1) and Bowen's disease (n = 1) were treated with patches containing 273.8-999 MBq (7.4-27 mCi) of Ho-166 for 30 min to 1 hr, Pathologic examination was performed 4-7 w k after treatment in an animal model. Skin biopsy was performed 8 wk p ost-treatment in four patients. Results: Tumor destruction was seen 1 wk posttreatment, however, radiation dermatitis or ulceration develope d at the site of radionuclide application. Those reactions healed grad ually with fibrosis or epithelialization, which was confirmed patholog ically. No significant adverse reaction to radiation except subcutaneo us fibrosis was found. Conclusion: Superficial skin tumors could be su ccessfully treated by topical application of beta-emitting radionuclid es.