Thick melanoma: the challenge persists

Abstract

Background: Considerable resources have been channelled into primary and secondary prevention of cutaneous melanoma over the past 20 years. These efforts have been associated with a significant increase in the proportion of thin, good prognosis lesions and this is felt to be the principal reason for the current overall improvement in melanoma survival.

Objectives: Analysis of Scottish Melanoma Group (SMG) data was carried out to identify the proportion of thick melanomas presenting over time. SMG data were used to characterize the patients presenting with thick melanoma.

Methods: Using data from the SMG database 915 patients (392 male and 523 female) first diagnosed with invasive melanoma > or = 3.5 mm thick in the two decades between 1979 and 1998, inclusive, were identified. The patients were from regions designated South-east Scotland, Tayside, Grampian and Highland, which together form half of all Scottish cases.

Results: The analysis shows that, although the proportion of thick, poor prognosis melanomas has decreased over time, the number presenting per year has not significantly altered. In the first decade, 50.5% of registrations were thick lesions and these fell to 31.0% in the second decade. In the first decade there were 419 cases (173 male), median age 66 years (range 5-99). Fifty-five patients were under the age of 40 years. Two hundred and twelve melanomas were nodular, 116 superficial spreading (SSM), 34 acral and 26 lentigo maligna melanoma. Sixty-nine patients had either lymph node involvement or distant spread at presentation. Despite a 93.3% increase in the total number of melanoma registrations by the end of the second decade, there was relatively little change in the absolute numbers of thick lesions. The total number of thick lesions was 496 (220 male), an increase of 18.4%. Median age was greater, at 70 years (range 1-98), and 31 patients were under the age of 40 years. Nodular was still the commonest type but its proportion had dropped significantly compared with the first decade, with a corresponding increase in SSM and acral types.

Conclusions: Over a 20-year period there was little change in the absolute number of patients presenting with thick melanoma each year, though these form a diminishing proportion of the rising number of total melanomas. This thick melanoma group is characterized by an increasingly older age group and a changing type profile, nodular and SSM being the most common types. This work suggests that the resources currently directed at public and professional education on melanoma are having no effect on this group of patients and that alternative strategies may need to be considered.