Phenocopies in melanoma-prone families with germ-line CDKN2A mutations

Protocol to evaluate a pilot program to upskill clinicians in providing genetic testing for familial melanoma

INTRODUCTION

Genetic testing for hereditary cancers can improve long-term health outcomes through identifying high-risk individuals and facilitating targeted prevention and screening/surveillance. The rising demand for genetic testing exceeds the clinical genetic workforce capacity. Therefore, non-genetic specialists need to be empowered to offer genetic testing. However, it is unknown whether patient outcomes differ depending on whether genetic testing is offered by a genetics specialist or a trained non-genetics clinician. This paper describes a protocol for upskilling non-genetics clinicians to provide genetic testing, randomise high-risk individuals to receive testing from a trained clinician or a genetic counsellor, and then determine whether patient outcomes differed depending on provider-type.

METHODS

An experiential training program to upskill dermatologically-trained clinicians to offer genetic testing for familial melanoma is being piloted on 10-15 clinicians, prior to wider implementation. Training involves a workshop, comprised of a didactic learning presentation, case studies, simulated sessions, and provision of supporting documentation. Clinicians later observe a genetic counsellor led consultation before being observed leading a consultation. Both sessions are followed by debriefing with a genetic counsellor. Thereafter, clinicians independently offer genetic testing in the clinical trial. Individuals with a strong personal and/or family history of melanoma are recruited to a parallel-group trial and allocated to receive pre- and post- genetic testing consultation from a genetic counsellor, or a dermatologically-trained clinician. A mixed method approach measures psychosocial and behavioural outcomes. Longitudinal online surveys are administered at five timepoints from baseline to one year post-test disclosure. Semi-structured interviews with both patients and clinicians are qualitatively analysed.

SIGNIFICANCE

This is the first program to upskill dermatologically-trained clinicians to provide genetic testing for familial melanoma. This protocol describes the first clinical trial to compare patient-reported outcomes of genetic testing based on provider type (genetic counsellors vs trained non-genetic clinicians).

Familial Melanoma and Susceptibility Genes: A Review of the Most Common Clinical and Dermoscopic Phenotypic Aspect, Associated Malignancies and Practical Tips for Management

A family history of melanoma greatly increases the risk of developing cutaneous melanoma, a highly aggressive skin cancer whose incidence has been steadily increasing worldwide. Familial melanomas account for about 10% of all malignant melanomas and display an inheritance pattern consistent with the presence of pathogenic germline mutations, among which those involving CDKN2A are the best characterized. In recent years, a growing number of genes, such as MC1R, MITF, CDK4, POT1, TERT, ACD, TERF2IP, and BAP1, have been implicated in familial melanoma. The fact that individuals harboring these germline mutations along with their close blood relatives have a higher risk of developing multiple primary melanomas as well as other internal organ malignancies, especially pancreatic cancer, makes cascade genetic testing and surveillance of these families of the utmost importance. Unfortunately, due to a polygenic inheritance mechanism involving multiple low-risk alleles, genetic modifiers, and environmental factors, it is still very difficult to predict the presence of these mutations. It is, however, known that germline mutation carriers can sometimes develop specific clinical traits, such as high atypical nevus counts and specific dermoscopic features, which could theoretically help clinicians predict the presence of these mutations in prone families. In this review, we provide a comprehensive overview of the high- and intermediate-penetrance genes primarily linked to familial melanoma, highlighting their most frequently associated non-cutaneous malignancies and clinical/dermoscopic phenotypes.

Parent and child perspectives on family interactions related to melanoma risk and prevention after CDKN2A/p16 testing of minor children

Predispositional genetic testing of children for adult-onset health risks is typically only used when prevention and screening measures have utility during childhood. Little is known about how children and their parents may use predispositional risk information, including whether it changes their interactions around risk-reducing prevention and screening behaviors. The current study examined perspectives on family interactions around skin cancer prevention and control practices through 1 year after test reporting and counseling among children who received melanoma predispositional genetic testing and their parents. Eighteen children (50% carriers, 56% male, mean age = 12.4 years) and 11 parents from 11 families participated in semi-structured interviews 1 month and 1 year after receiving the child's test result. Both parents (73%) and children (50%) reported making changes to family skin cancer prevention and control practices after receiving the test result. Parent- and child-reported discussions about melanoma prevention increased over time (36% parents and 61% children at 1 month, 73% parents and 67% at 1 year). One-quarter (27%) of parents and no children reported having conflicts about sun protection or screening 1 year after test reporting. A majority of parents (63%) reported treating their child differently at the 1-year follow-up, especially among carriers. Predispositional genetic testing for melanoma was associated with reported changes to plans for and discussions about sun protection, and high levels of parent-child collaboration to implement child sun protection. Future work could seek to identify child and parent factors and interactions that predict improved prevention and screening behaviors following pediatric predispositional genetic testing.

Variation in Cutaneous Patterns of Melanomagenesis According to Germline CDKN2A/CDK4 Status in Melanoma-Prone Families

CDKN2A and CDK4 are well-established melanoma susceptibility genes, but their effect on tumor location and distribution is unknown. We used a case-case study design to assess for differences in tumor location between mutation carriers (CDKN2A = 141 patients, 348 melanomas; CDK4 = 15 patients, 54 melanomas) and noncarriers (104 patients, 157 melanomas) in US melanoma-prone families. Associations between groups were assessed with chi-square tests. Odds ratios (ORs) for tumor location were adjusted for diagnosis age, gender, and superficial spreading subtype. Models included random effects to account for within individual and family correlations. Compared with having a truncal melanoma, CDK4 (vs. noncarriers: lower extremities OR = 14.5, 95% confidence interval [CI] = 5.02-42.0, P < 0.001; upper extremities OR = 6.88, 95% CI = 2.37-19.9, P < 0.001; head and neck OR = 18.6, 95% CI = 4.04-85.2, P < 0.001) and CDKN2A (vs. noncarriers: lower extremities OR = 3.01, 95% CI = 1.56-5.82, P < 0.05; upper extremities OR = 1.91, 95% CI = 1.03-3.52, P < 0.05; head and neck OR = 5.40, 95% CI = 2.10-13.9, P < 0.001) carriers had higher odds of developing melanoma at all other sites. Similar findings were observed for analyses stratified by gender, age, and first versus subsequent melanoma diagnoses. Further studies are needed to understand the biology underlying these genotype-associated patterns of tumor development, which could provide new insights into melanoma treatment and prevention.

Pediatric melanoma in melanoma-prone families

BACKGROUND

In the United States, only approximately 0.4% of all melanomas are diagnosed in patients aged <20 years. To the authors' knowledge, melanoma in pediatric members of melanoma-prone families has not been fully investigated to date. The objective of the current study was to evaluate pediatric patients with melanoma with extensive follow-up in melanoma-prone families with and without cyclin-dependent kinase inhibitor 2A (CDKN2A) mutations.

METHODS

For this non-population-based study, families were followed prospectively for up to 40 years. A total of 60 families with ≥ 3 patients with melanoma were included for analysis: 30 CDKN2A mutation-positive (CDKN2A+) and 30 CDKN2A mutation-negative (CDKN2A-) families. Age at the time of first melanoma and number of melanomas were obtained for each patient and summarized by family or sets (CDKN2A + vs CDKN2A-). For set comparisons and categorical variables (occurrence of melanoma in pediatric patients, number of melanomas, number of patients with single or multiple melanomas), the Pearson chi-square or Fisher exact test was used.

RESULTS

Regardless of CDKN2A status, melanoma-prone families were found to have 6-fold to 28-fold higher percentages of patients with pediatric melanoma compared with the general population of patients with melanoma in the United States. Within CDKN2A + families, pediatric patients with melanoma were significantly more likely to have multiple melanomas compared with their relatives who were diagnosed at age >20 years (71% vs 38%, respectively; P = .004). CDKN2A + families had significantly higher percentages of pediatric patients with melanoma compared with CDKN2A- families (11.1% vs 2.5%; P = .004).

CONCLUSIONS

These observations have implications for the prevention of melanoma as well as clinical care for its early detection. Children in melanoma-prone families should have careful sun protection from an early age and skin surveillance to reduce their risk of melanoma.