Host Characteristics and Risk of Incident Melanoma by Breslow Thickness

Nevus Count, Pigmentary Characteristics, and Melanoma-specific Mortality among Norwegian Women with Melanoma >1.0 mm Thick

Little is known about if and how nevi and pigmentation are associated with melanoma-specific mortality. However, increased melanoma awareness in people with lighter pigmentation and many nevi may result in earlier diagnosis of thinner less-lethal tumors. The aim of this study was to investigate associations between nevus count (asymmetrical > 5 mm and small symmetrical), pigmentary characteristics (hair colour, eye colour, skin colour, freckling, pigmentary score), and melanoma-specific mortality in subjects with melanomas > 1 mm. Data from the Norwegian Women and Cancer cohort, established in 1991, with complete follow-up of melanoma patients until 2018 through the Cancer Registry of Norway, were used to estimate hazard ratios with 95% confidence intervals for the associations between nevus count, pigmentary characteristics, and melanoma-specific mortality, stratified by tumor thickness using Cox regression. Estimated hazard ratios consistently indicated a higher risk of melanoma death for those with darker vs lighter pigmentary characteristics in patients with tumors > 1.0-2.0 mm and > 2.0 mm thick (e.g. pigmentary score hazard ratio 1.25, 95% confidence interval (0.74-2.13)). Among women with melanomas > 1.0 mm thick, lighter pigmentation and asymmetrical nevi may be associated with lower melanoma-specific mortality, suggesting that factors that increase the risk of melanoma may also be associated with decreased risk of death from melanoma.

Role of Occupation in Shaping Cancer Disparities

Simple Summary

The investigation of cancer disparities is of major importance. In this paper, we address this issue through the occupational point of view, trying to capture how work and its related factors impact on cancer inequalities. The data we provide may increase awareness relevant to cancer control, and stimulate further studies aimed at the identification of the occupational determinants of cancer disparities and the quantification of their role.

Abstract

Cancer occurrence is characterized globally by profound socioeconomic differences. Occupation is a fundamental component of socioeconomic status. In this review, we discuss the role of occupation as a determinant of cancer disparities. First, we address the issue of participation in cancer screening programs based on income, health insurance, occupational status and job title. Second, we review the role of occupation in contributing to disparities by acting as a mediator between cancer and (i) education and (ii) race/ethnicity. Lastly, we analyze data from a multicenter case−control study of lung cancer to calculate the mediating role of occupational exposure to diesel exhaust, silica and welding fumes in the association between education and lung cancer. By addressing the complex paths from occupation to cancer inequalities from multiple points of view, we provide evidence that occupational-related characteristics, such as income, health insurance, unemployment and hazardous exposures impinge on cancer control and outcomes. The increasing awareness of these aspects is fundamental and should lead to public health interventions to avoid inequalities rising from occupational factors.

Phenotypic Characteristics and Melanoma Thickness in Women

Patients' phenotypic characteristics might be associated with melanoma aggressiveness, but the evidence is scarce. This study examined the associations be-tween pigmentary characteristics, naevi and melanoma thickness. Data from the Norwegian Women and Cancer (NOWAC) study were analysed. By 2014, 1,243 women were diagnosed with a primary melanoma, and 1,140 had information on thickness. Using ordinal logistic regression models, the probability of being diagnosed with a specific thickness category was calculated by pigmentary score and naevi. Fair pigmentary score was associated with thinner trunk melanomas (probabilities of being diagnosed with a tumour ≤1.0 mm thickness were 74%, 66%, and 51% for fair, medium and dark pigmentary scores, respectively), but not the other sites. High number of naevi was associated with thicker nodular melanoma (NM) but not with super-ficial spreading melanoma. These findings suggest the need for greater overall vigilance and skin checks among women with fair pigmentary score. The association between naevi and NM suggest possible biological mechanisms.

Cohort Study of Nonmelanoma Skin Cancer and the Risk of Exfoliation Glaucoma

PRECIS

In a cohort study of 120,307 participants with 25+ years of follow-up, a history of nonmelanoma skin cancer (NMSC) was associated with a 40% higher exfoliation glaucoma (XFG) risk.

PURPOSE

The purpose of this study was to evaluate the relationship between NMSC (a marker of ultraviolet radiation exposure) and XFG.

METHODS

We performed a cohort study of US women (n=79,102; 1980-2014) and men (n=41,205; 1986-2014), aged 40+ years and at risk for glaucoma who reported eye examinations. From 1984 (women)/1988 (men), we asked about basal cell carcinoma or squamous cell carcinoma history separately; in prior years, we asked about any NMSC history in a single question. Squamous cell carcinoma was confirmed with histopathology reports while basal cell carcinoma and any early (<1984/<1988) NMSC history was self-reported. Incident XFG cases (362 women and 83 men) were confirmed with medical records. Using pooled data, we estimated multivariable-adjusted relative risks [MVRRs; 95% confidence intervals (CIs)] with Cox proportional hazards models that were stratified by age (in mo), 2-year time period at risk and average lifetime residential latitude.

RESULTS

In multivariable-adjusted analyses, we observed a 40% higher XFG risk with any NMSC history (MVRR=1.40; 95% CI=1.08-1.82); the association was observed even with 4 and 8-year lags in NMSC history. Also, the NMSC association was stronger in younger (below 65 y; MVRR=2.56; 95% CI=1.62-4.05) versus older participants (65 y and above; MVRR=1.25; 95% CI=0.94-1.66; P for interaction=0.01) and those living in the northern latitudes (≥42°N; MVRR=1.92; 95% CI=1.28-2.88) versus more southern latitudes (<42°N; MVRR=1.19; 95% CI=0.86-1.66; P for interaction=0.04).

CONCLUSION

NMSC was associated with higher XFG risk, particularly among younger participants and those living in the Northern US.

Differences in Risk Factors for Melanoma in Young and Middle-aged Higher-risk Patients

BACKGROUND/AIM

Differences in risk factors for melanoma between young adults (18-39 years) and middle-aged (40-60 years) are not well documented. In this study, we aimed to determine differences in risk factors and characteristics of melanoma between these groups.

PATIENTS AND METHODS

This retrospective study is a review on 330 patients, including 250 middle-aged and 80 young adults, during the period 2006-2016 in the Tampere university hospital, in Finland.

RESULTS

Forty-one per cent of middle-aged and 47% of young adults were defined as higher-risk patients. High nevus count was the most common host risk factor in both groups. Young were more likely to have a family history of melanoma. Middle-aged had more often excessive intermittent sun exposure and a history of sunburn. Host risk characteristics were less commonly associated with thicker melanomas.

CONCLUSION

A high number of patients have host risk factors for melanoma. Several differences exist in risk factors and characteristics of melanomas between young adults and middle-aged patients.

Germline variants are associated with increased primary melanoma tumor thickness at diagnosis

Germline genetic variants have been identified, which predispose individuals and families to develop melanoma.

Tumor thickness is the strongest predictor of outcome for clinically localized primary melanoma patients. We sought to determine whether there is a heritable genetic contribution to variation in tumor thickness. If confirmed, this will justify the search for specific genetic variants influencing tumor thickness.

To address this, we estimated the proportion of variation in tumor thickness attributable to genome-wide genetic variation (variant-based heritability) using unrelated patients with measured primary cutaneous melanoma thickness. As a secondary analysis, we conducted a genome-wide association study (GWAS) of tumor thickness.

The analyses utilized 10 604 individuals with primary cutaneous melanoma drawn from nine GWAS datasets from eight cohorts recruited from the general population, primary care and melanoma treatment centers. Following quality control and filtering to unrelated individuals with study phenotypes, 8125 patients were used in the primary analysis to test whether tumor thickness is heritable. An expanded set of 8505 individuals (47.6% female) were analyzed for the secondary GWAS meta-analysis. Analyses were adjusted for participant age, sex, cohort and ancestry.

We found that 26.6% (SE 11.9%, P = 0.0128) of variation in tumor thickness is attributable to genome-wide genetic variation. While requiring replication, a chromosome 11 locus was associated (P < 5 × 10⁻⁸) with tumor thickness. Our work indicates that sufficiently large datasets will enable the discovery of genetic variants associated with greater tumor thickness, and this will lead to the identification of host biological processes influencing melanoma growth and invasion.

Bioinformatic Analysis Identifies Potential Key Genes in the Pathogenesis of Melanoma

Melanoma is the deadliest skin tumor and is prone to distant metastases. The incidence of melanoma has increased rapidly in the past few decades, and current trends indicate that this growth is continuing. This study was aimed to explore the molecular mechanisms of melanoma pathogenesis and discover underlying pathways and genes associated with melanoma. We used high-throughput expression data to study differential expression profiles of related genes in melanoma. The differentially expressed genes (DEGs) of melanoma in GSE15605, GSE46517, GSE7553, and the Cancer Genome Atlas (TCGA) datasets were analyzed. Differentially expressed genes (DEGs) were identified by paired t-test. Then the DEGs were performed cluster and principal component analyses and protein–protein interaction (PPI) network construction. After that, we analyzed the differential genes through bioinformatics and got hub genes. Finally, the expression of hub genes was confirmed in the TCGA databases and collected patient tissue samples. Total 144 up-regulated DEGs and 16 down-regulated DEGs were identified. A total of 17 gene ontology analysis (GO) terms and 11 pathways were closely related to melanoma. Pathway of pathways in cancer was enriched in 8 DEGs, such as junction plakoglobin (JUP) and epidermal growth factor receptor (EGFR). In the PPI networks, 9 hub genes were obtained, such as loricrin (LOR), filaggrin (FLG), keratin 5 (KRT5), corneodesmosin (CDSN), desmoglein 1 (DSG1), desmoglein 3 (DSG3), keratin 1 (KRT1), involucrin (IVL), and EGFR. The pathway of pathways in cancer and its enriched DEGs may play important roles in the process of melanoma. The hub genes of DEGs may become promising melanoma candidate genes. Five key genes FLG, DSG1, DSG3, IVL, and EGFR were identified in the TCGA database and melanoma tissues. The results suggested that FLG, DSG1, DSG3, IVL, and EGFR might play important roles and potentially be valuable in the prognosis and treatment of melanoma. These hub genes might well have clinical significance as diagnostic markers.

Patterns of Omega-3 and Omega-6 Fatty Acid Dietary Intake and Melanoma Thickness at Diagnosis

BACKGROUND

Experimental evidence suggests that dietary intakes of omega-3 and omega-6 polyunsaturated fatty acids have divergent effects on melanoma growth, but epidemiologic evidence on their combined effect is lacking.

METHODS

In 634 Australian patients with primary melanoma, we assessed prediagnosis consumption of 39 food groups by food frequency questionnaires completed within 2 months of diagnosis. We derived, by reduced rank regression, dietary patterns that explained variability in selected omega-3 and omega-6 fatty acid intakes. Prevalence ratios (PR) and 95% confidence intervals (CI) for the association between tertiles of dietary patterns and melanoma thickness >2 mm versus ≤2 mm were estimated using Poisson regression.

RESULTS

Overall omega-3 fatty acid intakes were low. Two major fatty acid dietary patterns were identified: "meat, fish, and fat," positively correlated with intakes of all fatty acids; and "fish, low-meat, and low-fat," positively correlated with long-chain omega-3 fatty acid intake, and inversely with medium-chain omega-3 and omega-6 fatty acid intakes. Prevalence of thick melanomas was significantly higher in those in the highest compared with lowest tertile of the "meat, fish, and fat" pattern (PR, 1.40; 95% CI, 1.01-1.94), especially those with serious comorbidity (PR, 1.83; 95% CI, 1.15-2.92) or a family history (PR, 2.32; 95% CI, 1.00-5.35). The "fish, low-meat, and low-fat" pattern was not associated with melanoma thickness.

CONCLUSIONS

People with high meat, fish, and fat intakes, who thus consumed relatively high levels of omega-3 and high omega-6 fatty acid intakes, are more likely to be diagnosed with thick than thin melanomas.

IMPACT

High omega-3 and omega-6 fatty acid intakes may contribute to patients' presentation with thick melanomas.