Clinicopathological factors associated with death from thin (≤ 1·00 mm) melanoma

Abstract

Summary Background Thin cutaneous melanomas (≤ 1·00 mm) are increasing worldwide, causing around a quarter of all melanoma deaths in the U.S.A. and Australia. Identification of predictive factors for potentially fatal thin melanomas could allow better use of resources for follow‐up. Objectives To identify the clinicopathological factors associated with fatal thin melanomas. Methods This large, nested case–case study extracted data from the population‐based Queensland Cancer Registry, Australia. Our cohort consisted of Queensland residents aged 0–89 years who were diagnosed with a single, locally invasive thin melanoma (≤ 1·00 mm) between 1995 and 2014. Fatal cases (eligible patients who died from melanoma) were individually matched to three nonfatal cases (eligible patients who were not known to have died from melanoma) according to sex, age, year of diagnosis and follow‐up interval. Using conditional logistic regression, we calculated odds ratios (ORs) for melanoma‐specific death, adjusting for all collected clinicopathological variables. Results In the cohort, 27 660 eligible patients were diagnosed with a single, thin melanoma. The final case–case series included 424 fatal cases and 1189 nonfatal cases. Fatal cases were sixfold as likely to arise on the scalp as on the back [OR 6·39, 95% confidence interval (CI) 2·57–15·92] and six times as likely to be of thickness 0·80–1·00 mm as of < 0·30 mm (OR 6·00, 95% CI 3·55–10·17). Conclusions Scalp location is a strong prognostic factor of death from thin melanoma. Further, this study provides support that melanomas with a thickness of 0·80–1·00 mm are the more hazardous thin lesions. Patients with these tumour characteristics require specific attention during follow‐up. What's already known about this topic? Thin invasive melanomas (≤ 1·00 mm) contribute a substantial proportion of melanoma fatalities, owing to the high volume of disease. There is a need to find prognostic factors that will better identify fatal thin melanomas at the time of diagnosis. What does this study add? In this large population‐based study, fatal thin tumours were sixfold as likely to be located on the scalp as on the back. Thin melanomas of 0·80–1·00 mm thickness were six times as likely to be associated with death as tumours < 0·30 mm. Scalp location and increasing thickness are strong predictive factors of fatal thin melanomas, indicating that patients with these tumour characteristics require close follow‐up.

Comparing the characteristics and predicting the survival of patients with head and neck melanoma versus body melanoma: a population-based study

“…The 8th edition of the AJCC staging manual stated an increased risk of fatality in patients with a melanoma thickness of 0.8-1.0 mm [31]. Claeson et al reported that the risk of fatality in thin melanoma on the scalp was sixfold higher than that on the back [32]. As thin malignant melanomas accounted for a large number of melanomas in our study and scalp location is a risk factor, we explored the cutoff for thin HNM with X-tile, which revealed a thickness of 0.6 mm (Fig.…”

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“…Cancers of the skin are a major and growing disease burden among Caucasian populations. The primary driver of melanoma mortality is the thickness of the tumour at diagnosis; therefore, early detection of thin melanomas can optimize outcomes 1–3 . Diagnosing keratinocyte cancers at an early stage reduces the cost of surgical resection and rates of hospital admission 4 …”

Melanomas of the scalp: is hair coverage preventing early diagnosis?

“…They are usually thicker and have a higher risk for brain metastasis and poorer prognosis, when compared with other body sites or other head and neck melanomas 1–8 . Scalp location has also been recently proved to be a strong prognostic factor of death from thin (≤1.0 mm) melanoma 9 . The factors contributing to the worse prognosis and pathogenesis of scalp melanomas are not yet completely understood 1 …”