Topical immunotherapy of basal cell carcinomas with dinitrochlorobenzene.

One hundred thirteen tumors in 5 dinitrochlorobenzene (DNCB)-sensitized patients with multiple basal cell carcinomas were treated with topical DNCB. Thirty-six of the 113, or 32%, showed complete clinical regression, for periods of 5 to 18 months. An additional 29% (33 or 113) showed partial regression. DNCB induced only 15 to 25% complete regression in 4 of the 5 patients, whereas 21 of 30, or 70% of basal cell carcinomas treated with DNCB underwent complete regression in the 5th patient. In addition to variation of patient response, there was variation of response of tumors on the same patient. Photographic data presented separately are of a 6th patient with uncountable confluent basal cell carcinomas who responded well to DNCB, but in whom accurate quantification on an individual tumor basis was not possible. Controls in this study included 63 untreated tumors that were adjacent to and distant from treated tumors. These control tumors showed no evidence of regression. Eleven tumors treated with inert vehicles did not respond. One subject with over 100 nodular basal cell carcinomas became tolerant to DNCB and failed to respond to high concentrations of the drug. Croton oil, a primary irritant that induces inflammation without evidence of cell-mediated immunity, did cause complete regression in 6 of 26 (23%) treated tumors. The mechanism of DNCB-induced regression of basal cell carcinoma remains unknown. The disappearance of locally invasive human cancer following the therapeutic imposition of a controlled allergic contact dermatitis provides a useful model for the study of immunotherapy of cancer in humans.