Trends in prognostic factors of melanoma in South Australia, 1981-1992: implications for health promotion.

OBJECTIVE

To analyse trends in prognostic factors at diagnosis of melanoma to indicate targets for health promotion.

METHODS

Cases of melanoma notified to the South Australian Cancer Registry during 1981-1992 (1361 in situ and 4509 invasive) were analysed by tumour site, histological type, stage, thickness, period of diagnosis and sociodemographic characteristics of the patient.

RESULTS

The relative probability of being diagnosed with an in-situ, rather than a thin invasive, lesion increased progressively between 1984-1986 and 1990-1992. The relative probability of having an in-situ melanoma diagnosed was: lower among those aged 80 years or more; higher among patients residing in the upper socioeconomic areas of Adelaide; high for lesions on the face; and high for lentigo maligna as opposed to superficial spreading lesions. The relative probability of invasive lesions being diagnosed when more than 1.5 mm thick decreased progressively between the 1981-1983 and 1990-1992 diagnosis periods. The relative probability of thick lesions being diagnosed was higher among older patients and for nodular lesions compared with superficial spreading or lentigo maligna lesions. Facial lesions and those in males tended to be thicker.

CONCLUSIONS

There are favourable trends towards earlier detection of melanomas in South Australia, probably reflecting the effect of skin-cancer awareness campaigns. Further campaigns should emphasise early detection in people aged 60 years and over, males and residents of less affluent areas. Early detection of nodular melanomas and invasive lesions of the face also warrants special attention.