PROGNOSTIC MODELS FOR SUBGROUPS OF MELANOMA PATIENTS FROM THE SCOTTISH-MELANOMA-GROUP DATABASE 1979-86, AND THEIR SUBSEQUENT VALIDATION

For the past 20 years thickness of the primary tumour has been accepte d as the most important guide to prognosis for patients with primary c utaneous malignant melanoma. The changing epidemiology of melanoma wit h an increasing number of patients with thin tumours has necessitated a reappraisal of this, with particular reference to interactions among tumour thickness, the patients' sex and the presence or absence of ul ceration of the primary tumour. All primary cutaneous malignant melano mas diagnosed in Scotland between 1979 and 1986 were used as the test group (1978 patients). The proportional hazards model was used on all potential risk factors in the database and their two-way interactions, and the resulting models based on stepwise procedures were subsequent ly validated on 289 melanoma patients first diagnosed in 1987 in the s ame geographic area. Four distinct subgroups of males and females with ulcerated or non-ulcerated lesions were identified. For females with ulcerated lesions, tumour thickness, mitotic count and anatomical site of primary all gave valuable prognostic information, whereas for fema les with non-ulcerated lesions only tumour thickness was of prognostic value. For males with ulcerated lesions, level of invasion was the on ly prognostic guide, while for males with non-ulcerated lesions both t umour thickness and level of invasion contributed significantly to pre diction of prognosis. Prognosis is markedly different across subgroups of the melanoma population, even to the extent that essential prognos tic factors are not the same in the distinct subgroups. Verification o f these prognostic guides derived from 1979-86 patients has been achie ved for all patients diagnosed with melanoma in 1987 from the same geo graphic area. These data will therefore be useful aids for clinicians managing patients.