Clinicopathological characteristics of cutaneous malignant melanoma in patients at a tertiary hospital in Macaronesia. Survival as a function of locoregional prognostic factors per the American Joint Committee on Cancer

BACKGROUND

Despite suffering high ultraviolet radiation levels, few data on malignant melanoma (MM) in Macaronesia are available.

METHODS

Observational study of cutaneous MM cases diagnosed during a period of 12 years at a tertiary hospital in Canary Islands.

RESULTS

A total of 532 patients (female/male = 1.4) with an average age of 56 years were included; 5% developed more than one MM, and 7% reported family history of MM. Phototype II (43%), dark eyes (41%), and dark hair (41%) predominated. There was a lower frequency of light-colored hair and eyes in those born in the Canary Islands. The most frequent locations of MM were on the back for men (37%) and on the lower extremities for women (35%). Among the infiltrating tumors (83%), the (median) thickness was 1.07 mm (women, 0.90 mm; men, 1.21 mm). Anatomopathological ulceration (AU) and a mitotic rate ≥1 mitosis/mm² (HMR) were recorded in 27% of patients. Patients with regional disease constituted 12% of the population. The most common stage was IA (34%). Melanoma-specific survival (MSSV) decreased significantly with thickness, presence of AU, HMR, and sentinel lymph node disease. These four variables were independent prognostic factors. The five-year MSSV varied between 100% (stage IA) and 39% (stage IIIC).

CONCLUSIONS

The characteristics of the patients were similar to those published in datasets from continental Europe, although the pigmentary features were darker in those originating from Macaronesia. The prognostic parameters described in the 7th edition of the American Joint Committee on Cancer (AJCC) independently predict MSSV in our patients.

MC1R gene variants and sporadic malignant melanoma susceptibility in the Canary Islands population

Several MC1R variants are associated with increased risk of malignant melanoma (MM) in a variety of populations. We aim to examine the influence of the MC1R variants (RHC: D84E, R151C, R160W; NRHC: V60L, R163Q and the synonymous polymorphism T314T) on the MM risk in a population from the Canary Islands. Overall, 1,046 Caucasian individuals were included in the study. A thousand of them were genotyped for MC1R variants: 509 were sporadic MM patients and 491 were healthy control subjects from general population. The analysis was adjusted for age, sex, hair colour, eye colour, skin phototype and ancestry. We found that carriers of the R151C and R163Q variants were at an increased risk for melanoma OR 2.76 (1.59-4.78) and OR 5.62 (2.54-12.42), respectively. The risk of carrying RHC variants was 3.04 (1.90-4.86). Current study confirms the increased MM risk for R151C carriers. It also supports the association between R163Q variant and MM risk in the population on the Canary Islands, as opposed to reported on northern populations. These results highlight the importance of the sample population selection in this kind of studies.

Melanocortin-1 receptor, skin cancer and phenotypic characteristics (M-SKIP) project: study design and methods for pooling results of genetic epidemiological studies

Background

For complex diseases like cancer, pooled-analysis of individual data represents a powerful tool to investigate the joint contribution of genetic, phenotypic and environmental factors to the development of a disease. Pooled-analysis of epidemiological studies has many advantages over meta-analysis, and preliminary results may be obtained faster and with lower costs than with prospective consortia.

Design and methods

Based on our experience with the study design of the Melanocortin-1 receptor (MC1R) gene, SKin cancer and Phenotypic characteristics (M-SKIP) project, we describe the most important steps in planning and conducting a pooled-analysis of genetic epidemiological studies. We then present the statistical analysis plan that we are going to apply, giving particular attention to methods of analysis recently proposed to account for between-study heterogeneity and to explore the joint contribution of genetic, phenotypic and environmental factors in the development of a disease. Within the M-SKIP project, data on 10,959 skin cancer cases and 14,785 controls from 31 international investigators were checked for quality and recoded for standardization. We first proposed to fit the aggregated data with random-effects logistic regression models. However, for the M-SKIP project, a two-stage analysis will be preferred to overcome the problem regarding the availability of different study covariates. The joint contribution of MC1R variants and phenotypic characteristics to skin cancer development will be studied via logic regression modeling.

Discussion

Methodological guidelines to correctly design and conduct pooled-analyses are needed to facilitate application of such methods, thus providing a better summary of the actual findings on specific fields.