NODULAR HISTOGENETIC TYPE - THE MOST SIGNIFICANT FACTOR FOR THICK MELANOMA - IMPLICATIONS FOR PREVENTION

Tumour thickness is the most important prognostic factor in malignant melanoma. To reduce the melanoma-related mortality, factors related to the presentation of thick melanoma have to be identified. Three sampl es of melanoma patients (n = 694) were studied for this purpose. Histo genetic type was the only factor which differentiated between 'thin' ( less than or equal to 0.8 mm) and 'thick' (> 2.0 mm) lesions. During a 10-year period only 3% of the nodular lesions were 'thin' at diagnosi s. Differences in knowledge about melanoma or the location of the lesi on (either 'easy' or 'difficult' for the patient to observe) did not e xplain differences in tumour thickness. The most common tumour site ir respective of histogenetic type and gender was 'back of the trunk'. 'I ncrease in diameter' and 'bleeding' were the symptoms most frequently reported by patients with 'thick' melanoma. 'Thick' lesions were diagn osed in older age groups and in men to a greater extent. Considering t hese results, melanoma prevention should also be targeted to older age groups and attention should be paid to symptoms such as 'increase in diameter' even in the absence of other characteristic symptoms of mela noma. An increased proportion of nodular melanoma diagnosed as 'thin' lesions can be interpreted as a step forward in secondary prevention. (C) 1998 Lippincott Williams & Wilkins.