Skin reactivity to dinitrochlorobenzene in cancer patients.

Delayed skin hypersensitivity to DNCB was evaluated in 179 patients with cancer and in 71 control subjects. Cancer patients had a lower incidence of positive reactions than controls (50.2 vs. 84.5%, p less than 0.001). Incidence of impaired skin reactions in cancer patients varied according to the tumor type. Reactivity was most depressed in patients with lymphatic tumors (23.3% positive results) and least depressed in those with male genitourinary cancer (64.3% positive results). The number of positive results was significantly higher in cancer patients with localized tumor than in those with disseminated disease (60.2% vs. 44.1%, p less than 0.05). DNCB reactivity correlated well with the subsequent course of disease. Incidence of positive results in patients who had remained free of disease after 12 months of follow-up (64.3%) was significantly higher than in patients who had progressive disease (33.3%) or who died of disease (44.8%).