Independent evaluation of melanoma polygenic risk scores in UK and Australian prospective cohorts

Global, regional, and national trends in the burden of melanoma and non-melanoma skin cancer: insights from the global burden of disease study 1990-2021

This study examines global, regional, and national trends in melanoma and non-melanoma skin cancer (NMSC) burden from 1990 to 2021, their socioeconomic associations, and projects future trends. Data was extracted from the Global Burden of Disease (GBD) 2021 database, focusing on malignant melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Joinpoint regression, age-period-cohort modeling, and decomposition analysis were used to assess temporal trends. The Socio-Demographic Index (SDI) was applied to examine the correlation between skin cancer burden and socioeconomic development, and ARIMA models forecasted future trends. The global burden of skin cancers has shown significant growth over the study period, with the age-standardized incidence rate (ASIR) rising globally (Estimated Annual Percentage Change, EAPC = 1.94%) from 1990 to 2021. This increase was particularly pronounced for BCC and SCC, while the melanoma DALYs rate declined (EAPC = -0.67%). In 2021, the most recent year covered, the global incidence of skin cancers was 6.64 million cases, with an ASIR of 77.66 per 100,000 and a disability-adjusted life years (DALYs) burden of 2.89 million cases. Significant geographic disparities were observed, with Australasia and North America reporting the highest ASIR, while middle-SDI regions exhibited rapid increases. Skin cancer incidence is rising globally, driven by demographic changes, increased UV exposure, and improved detection. The burden of melanoma has decreased, which may be related to advances in treatment. Targeted prevention, equitable access to care, and tailored regional strategies are crucial to mitigating the growing impact of skin cancers worldwide.

Polygenic Risk Scores Driving Clinical Change in Glaucoma

Glaucoma is a clinically heterogeneous disease and the world's leading cause of irreversible blindness. Therapeutic intervention can prevent blindness but relies on early diagnosis, and current clinical risk factors are limited in their ability to predict who will develop sight-threatening glaucoma. The high heritability of glaucoma makes it an ideal substrate for genetic risk prediction, with the bulk of risk being polygenic in nature. Here, we summarize the foundations of glaucoma genetic risk, the development of polygenic risk prediction instruments, and emerging opportunities for genetic risk stratification. Although challenges remain, genetic risk stratification will significantly improve glaucoma screening and management.

A Narrative Review: Opportunities and Challenges in Artificial Intelligence Skin Image Analyses Using Total Body Photography

Artificial intelligence (AI) algorithms for skin lesion classification have reported accuracy at par with and even outperformance of expert dermatologists in experimental settings. However, the majority of algorithms do not represent real-world clinical approach where skin phenotype and clinical background information are considered. We review the current state of AI for skin lesion classification and present opportunities and challenges when applied to total body photography (TBP). AI in TBP analysis presents opportunities for intrapatient assessment of skin phenotype and holistic risk assessment by incorporating patient-level metadata, although challenges exist for protecting patient privacy in algorithm development and improving explainable AI methods.

Assessing the genetic risk of nodular melanoma using a candidate gene approach

BACKGROUND

Nodular melanoma (NM) is a challenge to diagnose early due to its rapid growth and more atypical clinical presentation, making it the largest contributor to melanoma mortality.

OBJECTIVES

Our study aim was to perform a rare-variant allele (RVA) analysis of whole-exome sequencing of patients with NM and non-NM (minor allele frequency ≤ 1% non-Finnish European) for a set of 500 candidate genes potentially implicated in melanoma.

METHODS

This study recruited 131 participants with NM and 194 with non-NM from South-east Queensland and patients with NM from Victoria to perform a comparative analysis of possible genetic differences or similarities between the two melanoma cohorts.

RESULTS

Phenotypic analysis revealed that a majority of patients diagnosed with NM were older males with a higher frequency of fair skin and red hair than is seen in the general population. The distribution of common melanoma polygenic risk scores was similar in patients with NM and non-NM, with over 28% in the highest quantile of scores. There was also a similar frequency of carriage of familial/high-penetrant melanoma gene and loss-of-function variants. We identified 39 genes by filtering 500 candidate genes based on the greatest frequency in NM compared with non-NM cases. The genes with RVAs of greatest frequency in NM included PTCH1, ARID2 and GHR. Rare variants in the SMO gene, which interacts with PTCH1 as ligand and receptor, were also identified, providing evidence that the Hedgehog pathway may contribute to NM risk. There was a cumulative effect in carrying multiple rare variants in the NM-associated genes. A 14.8-fold increased ratio for NM compared with non-NM was seen when two RVAs of the 39 genes were carried by a patient.

CONCLUSIONS

This study highlights the importance of considering frequency of RVA to identify those at risk of NM in addition to known high penetrance genes.

Does genetic risk modify the effect of skin screening on melanoma detection rates?

BACKGROUND

Skin screening is associated with higher melanoma detection rates, a potential indicator of overdiagnosis, but it remains possible that this effect is due to confounding by genetic risk.

OBJECTIVES

To compare melanoma incidence among screened vs. unscreened participants within tertiles of genetic risk.

METHODS

We investigated melanoma incidence in the QSkin study, a prospective cohort study which for this analysis comprised 15 283 participants aged 40-69 years with genotype data and no prior history of melanoma. We calculated a polygenic score (PGS) for melanoma. We first calculated the age-standardized rate (ASR) of melanoma within PGS tertiles, and then measured the association between skin examination and melanoma detection by calculating the hazard ratio (HR) and 95% confidence interval (95% CI), overall and within PGS tertiles.

RESULTS

Melanoma incidence increased with PGS (ASR per 100 000 per year): tertile 1 = 442; tertile 2 = 519; tertile 3 = 871. We found that the HRs for all melanomas (i.e. in situ and invasive) associated with skin examination differed slightly across PGS tertiles [age- and sex-adjusted tertile 1 HR 1.88 (95% CI 1.26-2.81); tertile 2 HR 1.70 (95% CI 1.20-2.41); tertile 3 HR 1.96 (95% CI 1.43-2.70); fully adjusted tertile 1 HR 1.14 (95% CI 0.74-1.75); tertile 2 HR 1.21 (95% CI 0.82-1.78); tertile 3 HR 1.41 (95% CI 1.00-1.98)], but these differences were not statistically significant. HRs for in situ melanoma associated with skin examination were similar across PGS tertiles. For invasive melanomas, the point estimates appeared to be highest in PGS tertile 3 in both the minimally adjusted (age, sex) and fully adjusted models; however, these apparent differences were also not statistically significant.

CONCLUSIONS

Genetic risk predicts subsequent melanoma incidence, and is weakly associated with screening behaviour, but it does not explain the higher rate of melanoma detection between screened and unscreened people.

Acceptability and appropriateness of a risk-tailored organised melanoma screening program: Qualitative interviews with key informants

INTRODUCTION

In Australia, opportunistic screening (occurring as skin checks) for the early detection of melanoma is common, and overdiagnosis is a recognised concern. Risk-tailored cancer screening is an approach to cancer control that aims to provide personalised screening tailored to individual risk. This study aimed to explore the views of key informants in Australia on the acceptability and appropriateness of risk-tailored organised screening for melanoma, and to identify barriers, facilitators and strategies to inform potential future implementation. Acceptability and appropriateness are crucial, as successful implementation will require a change of practice for clinicians and consumers.

METHODS

This was a qualitative study using semi-structured interviews. Key informants were purposively selected to ensure expertise in melanoma early detection and screening, prioritising senior or executive perspectives. Consumers were expert representatives. Data were analysed deductively using the Tailored Implementation for Chronic Diseases (TICD) checklist.

RESULTS

Thirty-six participants were interviewed (10 policy makers; 9 consumers; 10 health professionals; 7 researchers). Key informants perceived risk-tailored screening for melanoma to be acceptable and appropriate in principle. Barriers to implementation included lack of trial data, reluctance for low-risk groups to not screen, variable skill level in general practice, differing views on who to conduct screening tests, confusing public health messaging, and competing health costs. Key facilitators included the perceived opportunity to improve health equity and the potential cost-effectiveness of a risk-tailored screening approach. A range of implementation strategies were identified including strengthening the evidence for cost-effectiveness, engaging stakeholders, developing pathways for people at low risk, evaluating different risk assessment criteria and screening delivery models and targeted public messaging.

CONCLUSION

Key informants were supportive in principle of risk-tailored melanoma screening, highlighting important next steps. Considerations around risk assessment, policy and modelling the costs of current verses future approaches will help inform possible future implementation of risk-tailored population screening for melanoma.

The role of polygenic risk scores in breast cancer risk perception and decision-making

Polygenic risk scores (PRS) have the potential to improve the accuracy of clinical risk assessments, yet questions about their clinical validity and readiness for clinical implementation persist. Understanding how individuals integrate and act on the information provided by PRS is critical for their effective integration into routine clinical care, yet few studies have examined how individuals respond to the receipt of polygenic risk information. We conducted an embedded Ethical, Legal, and Social Implications (ELSI) study to examine if and how unaffected participants in a US population breast cancer screening trial understood and utilized PRS, as part of a multifactorial risk score combining traditional risk factors with a genetic risk assessment, to make screening and risk-reduction decisions. Semi-structured qualitative interviews were conducted with 24 trial participants who were designated at elevated risk for breast cancer due to their combined risk score. Interviews were analyzed using a grounded theory approach. Participants understood PRS conceptually and accepted it as one of many risk factors to consider, yet the value and meaning they ascribed to this risk estimate varied. Most participants reported financial and insurance barriers to enhanced screening with MRI and were not interested in taking risk-reducing medications. These findings contribute to our understanding of how PRS may be best translated from research to clinical care. Furthermore, they illuminate ethical concerns about identifying risk and making recommendations based on polygenic risk in a population screening context where many may have trouble accessing appropriate care.

Polygenic scores in cancer

Since the publication of the first genome-wide association study for cancer in 2007, thousands of common alleles that are associated with the risk of cancer have been identified. The relative risk associated with individual variants is small and of limited clinical significance. However, the combined effect of multiple risk variants as captured by polygenic scores (PGSs) may be much greater and therefore provide risk discrimination that is clinically useful. We review the considerable research efforts over the past 15 years for developing statistical methods for PGSs and their application in large-scale genome-wide association studies to develop PGSs for various cancers. We review the predictive performance of these PGSs and the multiple challenges currently limiting the clinical application of PGSs. Despite this, PGSs are beginning to be incorporated into clinical multifactorial risk prediction models to stratify risk in both clinical trials and clinical implementation studies.

Melanoma risk prediction based on a polygenic risk score and clinical risk factors

Melanoma is one of the most commonly diagnosed cancers in the Western world: third in Australia, fifth in the USA and sixth in the European Union. Predicting an individual's personal risk of developing melanoma may aid them in undertaking effective risk reduction measures. The objective of this study was to use the UK Biobank to predict the 10-year risk of melanoma using a newly developed polygenic risk score (PRS) and an existing clinical risk model. We developed the PRS using a matched case-control training dataset ( N  = 16 434) in which age and sex were controlled by design. The combined risk score was developed using a cohort development dataset ( N  = 54 799) and its performance was tested using a cohort testing dataset ( N  = 54 798). Our PRS comprises 68 single-nucleotide polymorphisms and had an area under the receiver operating characteristic curve of 0.639 [95% confidence interval (CI) = 0.618-0.661]. In the cohort testing data, the hazard ratio per SD of the combined risk score was 1.332 (95% CI = 1.263-1.406). Harrell's C-index was 0.685 (95% CI = 0.654-0.715). Overall, the standardized incidence ratio was 1.193 (95% CI = 1.067-1.335). By combining a PRS and a clinical risk score, we have developed a risk prediction model that performs well in terms of discrimination and calibration. At an individual level, information on the 10-year risk of melanoma can motivate people to take risk-reduction action. At the population level, risk stratification can allow more effective population-level screening strategies to be implemented.

Polygenic risk scores for melanoma: a stepwise process towards clinical implementation

Linked Article: Steinberg et al. Br J Dermatol 2022; 186:823–834.