Differential sensitivity among 3 human subpopulations in response to 4-nitroquinoline-1-oxide and to bleomycin.

An assay employing the UV-mimetic mutagen 4-nitroquinoline-1-oxide (4NQO) to estimate a person's UV-sensitivity was developed. This sensitivity may be translated into an individual's susceptibility to acquire cutaneous malignancies. We used cytogenetic recordings on cultured lymphocytes from 103 normal individuals, 62 melanoma patients, and 71 patients with head and neck cancer. The frequency of chromosome damage (chromatid breaks) caused by exposure to 4NQO was used to measure sensitivity. Preliminary results showed that a significantly higher proportion of melanoma patients was 4NQO sensitive compared to the other two groups, whose 4NQO sensitivity was statistically not different. Although a number of theoretical and technical problems remain to be resolved and a great deal of additional information (especially clinical and epidemiological) is needed, it appears that 4NQO sensitivity may be effectively employed as a biological marker for identification of individuals at risk for melanoma (and possibly other cutaneous neoplasms as well).