Skin typing for assessment of skin cancer risk and acute response to UV-B and oral methoxsalen photochemotherapy.

Skin typing is a clinical classification system based on a patient's historical reporting of the acute skin response to sunlight. It is advocated as a means of determining an individual's relative risk of skin tumors and has been used to determine the initial therapeutic dose of UV radiation for UV-B phototherapy or oral methoxsalen photochemotherapy (PUVA) for psoriasis. Among PUVA-treated patients, the relative risk of cutaneous carcinoma was significantly higher among patients with skin types I and II compared with patients with skin type IV (3.2 and 2.3, respectively). Skin type was a better predictor of this risk than eye or hair color. The minimal erythemal dose ( MErD ) and minimal phototoxic dose (MPD) increased with increasing skin type number, but within a given skin type each varied as much as sixfold. Skin type was a good clinical predictor of skin cancer risk, but lacked specificity as a predictor of an individual's MErD or MPD.