[Recommendations for genetic testing and management of individuals genetically at-risk of cutaneous melanoma]

Molecular landscape of Hereditary Melanoma

Melanoma is considered the most lethal skin cancer and its incidence has increased during the past decades. About 10 % of cases are classified as hereditary melanoma. Genetic predisposition usually manifests itself clinically as early onset and multiple cutaneous melanomas. Several genes have been identified as involved to melanoma susceptibility, some of them still with unknown clinical relevance. Beyond melanoma, the affected families are also more prone to develop other malignancies, such as pancreatic cancer. The identification of risk families and involved genes is of great importance, since different forms of oncological surveillance are recommended. However, well established guidelines to standardize both the selection of individuals and the genetic panel to be requested are still lacking. Given the importance of the genetic counseling and testing in the context of clinical suspicion of hereditary melanoma, this paper aims to review the literature regarding genetic panel indications worldwide.

Feedback of extended panel sequencing in 1530 patients referred for suspicion of hereditary predisposition to adult cancers

High‐throughput sequencing analysis represented both a medical diagnosis and technological revolution. Gene panel analysis is now routinely performed in the exploration of hereditary predisposition to cancer, which is becoming increasingly heterogeneous, both clinically and molecularly. We present 1530 patients with suspicion of hereditary predisposition to cancer, for which two types of analyses were performed: a) oriented according to the clinical presentation (n = 417), or b) extended to genes involved in hereditary predisposition to adult cancer (n = 1113). Extended panel analysis had a higher detection rate compared to oriented analysis in hereditary predisposition to breast / ovarian cancer (P < .001) and in digestive cancers (P < .094) (respectively 15% vs 5% and 19.3%, vs 12.5%). This higher detection is explained by the inclusion of moderate penetrance genes, as well as the identification of incident mutations and double mutations. Our study underscores the utility of proposing extended gene panel analysis to patients with suspicion of hereditary predisposition to adult cancer.

Insights into Genetic Susceptibility to Melanoma by Gene Panel Testing: Potential Pathogenic Variants in ACD, ATM, BAP1, and POT1

The contribution of recently established or candidate susceptibility genes to melanoma missing heritability has yet to be determined. Multigene panel testing could increase diagnostic yield and better define the role of candidate genes. We characterized 273 CDKN2A/ARF and CDK4-negative probands through a custom-designed targeted gene panel that included CDKN2A/ARF, CDK4, ACD, BAP1, MITF, POT1, TERF2IP, ATM, and PALB2. Co-segregation, loss of heterozygosity (LOH)/protein expression analysis, and splicing characterization were performed to improve variant classification. We identified 16 (5.9%) pathogenic and likely pathogenic variants in established high/medium penetrance cutaneous melanoma susceptibility genes (BAP1, POT1, ACD, MITF, and TERF2IP), including two novel variants in BAP1 and 4 in POT1. We also found four deleterious and five likely deleterious variants in ATM (3.3%). Thus, including potentially deleterious variants in ATM increased the diagnostic yield to about 9%. Inclusion of rare variants of uncertain significance would increase the overall detection yield to 14%. At least 10% of melanoma missing heritability may be explained through panel testing in our population. To our knowledge, this is the highest frequency of putative ATM deleterious variants reported in melanoma families, suggesting a possible role in melanoma susceptibility, which needs further investigation.

[Skin cancers in Madagascar: where do we stand?]

Introduction

Skin cancers are malignant keratinizing tumors of epidermal, melaninic or adnexal origin. These cancers are still little known. However they affect people living in Madagascar where the amount of sunshine remains very high with an impact that varies depending on the skin type. The purpose of our study was to determine the epidemio-clinical profile of skin cancers in Antananarivo.

Methods

We conducted a retrospective descriptive study of skin cancers in the Department of Oncology of the Joseph Ravoahangy Andrianavalona Hospital, Antananarivo over a period of seven years. It included patients with tumoral skin lesions confirmed by histological examination.

Results

We collected data from 47 cases of skin cancers (male predominance; sex ratio 1.13). The average age of patients was 49.3 years. Farmers were the most affected. The lesions mainly occurred in the head, neck (44%) and lower limbs (42%). Localized skin cancers were detected in 61.7% of cases. Squamous cell carcinoma was the most common skin cancer in Madagascar (37%), followed by the melanoma (21%) and the basal cell carcinoma (11%). Treatment was mainly based on surgery (74.19%).

Conclusion

Squamous cell carcinoma is the most common cancer in Madagascar, followed by melanoma and basal cell carcinoma. Skin cancers affect mainly the young population and require appropriate management.

[Malignant mesothelioma and constitutional BAP1 gene mutations]

Malignant mesothelioma is a rare tumour, usually the result of asbestos exposure. Several cases of familial aggregation have been reported and recently shown to be associated with constitutional mutations of the BAP1 gene. BAP1 is a deubiquitinating enzyme implicated in several different cellular mechanisms such as the repair or differentiation of DNA. About a half of malignant mesotheliomas present a somatic, bi-allelic inactivation of BAP1, demonstrated by nuclear extinction on histochemistry. Constitutional alterations of BAP1 are extremely rare. Present in the heterozygous state they are transmitted as an autosomal dominant. They are associated with a risk of developing other tumours such as uveal and cutaneous melanomas, benign melanocytic tumours (melanocytic BAP1-mutated atypical intradermal tumour or MBAITS) and clear cell renal carcinomas. The causal link between mesothelioma and germinal mutations of BAP1 has still not been clearly identified. At present there is, in France, no consensus on recommendations for the management of patients with these mutations. This article is a synthesis of the literature on the functions of the BAP1 gene, the tumour risks related to its alteration and the follow up of patients bearing a constitutional mutation.

Improvement of Genetic Testing for Cutaneous Melanoma in Countries With Low to Moderate Incidence: The Rule of 2 vs the Rule of 3

Importance

Genetic testing for melanoma-prone mutation in France, a country with low to moderate incidence of melanoma, is proposed in cases with 2 invasive cutaneous melanomas and/or related cancers in the same patient, or in first- or second-degree relatives (rule of 2). In preclinical studies, these rules led to disclosure of mutation(s) in more than 10% of these families, the threshold widely accepted to justify genetic testing for cancers.

Objective

To reconsider these criteria in a general population testing of patients.

Design, Setting, and Participants

This was a retrospective study, performed from 2004 to 2015 at Angers and Lyons University Hospitals, of a cohort of 1032 patients who underwent genetic testing.

Main Outcomes and Measures

Frequency of mutation in high (CDKN2A, CDK4, and BAP1) and intermediate (MITF) susceptibility genes; statistical effect of histologic subtype, age, dysplastic nevi syndrome, and associated cancers on mutation rate; and evaluation of cases with anamnestic uncertainty.

Results

The mutation rate was 67 of 1032 patients (6.5%). Their mean (SD) age was 54.5 (14.2) years [range, 18-89 years], and 543 (52.6%) were men. It increased to 38 of 408 patients (9.3%) when applying a rule of 3 (those with ≥3 primary melanomas or genetically related cancers) (P = .68) and to 27 of 150 patients (18.0%) with a rule of 4 (4 primary melanomas or related cancer) (P < .001). The impact of age at first melanoma was observed only in those younger than 40 years, with a rate of 32 of 263 (12.1%) (P = .12) for the rule of 2 and 22 of 121 (18.2%) (P = .001) for the rule of 3. Use of the rule of 2 in patients younger than 40 years reduced the number of missed CDKN2A-mutated-families when applying the rule of 3 from 14 of 43 to 7 of 43. Anamnestic uncertainty, found in 88 families (8.5%), if excluded, would have led us to withdraw of only 21 cases (23.8%), and only 1 mutation would have been missed.

Conclusions and Relevance

We propose using the rule of 3 to recommend genetic testing in France and countries with low to moderate incidence of melanoma, except in families and patients with a first melanoma occurrence before age 40 years in whom the rule of 2 could be maintained.

French updated recommendations in Stage I to III melanoma treatment and management

As knowledge continues to develop, regular updates are necessary concerning recommendations for practice. The recommendations for the management of melanoma stages I to III were drawn up in 2005. At the request of the Société Française de Dermatologie, they have now been updated using the methodology for recommendations proposed by the Haute Autorité de Santé in France. In practice, the principal recommendations are as follows: for staging, it is recommended that the 7th edition of AJCC be used. The maximum excision margins have been reduced to 2 cm. Regarding adjuvant therapy, the place of interferon has been reduced and no validated emerging medication has yet been identified. Radiotherapy may be considered for patients in Stage III at high risk of relapse. The sentinel lymph node technique remains an option. Initial examination includes routine ultrasound as of Stage II, with other examinations being optional in stages IIC and III. A shorter strict follow-up period (3 years) is recommended for patients, but with greater emphasis on imaging.

Multiple primary melanomas (MPMs) and criteria for genetic assessment: MultiMEL, a multicenter study of the Italian Melanoma Intergroup

BACKGROUND

Multiple primary melanoma (MPM), in concert with a positive family history, is a predictor of cyclin-dependent kinase (CDK) inhibitor 2A (CDKN2A) germline mutations. A rule regarding the presence of either 2 or 3 or more cancer events (melanoma and pancreatic cancer) in low or high melanoma incidence populations, respectively, has been established to select patients for genetic referral.

OBJECTIVE

We sought to determine the CDKN2A/CDK4/microphthalmia-associated transcription factor mutation rate among Italian patients with MPM to appropriately direct genetic counseling regardless of family history.

METHODS

In all, 587 patients with MPM and an equal number with single primary melanomas and control subjects were consecutively enrolled at the participating centers and tested for CDKN2A, CDK4, and microphthalmia-associated transcription factor.

RESULTS

CDKN2A germline mutations were found in 19% of patients with MPM versus 4.4% of patients with single primary melanoma. In familial MPM cases the mutation rate varied from 36.6% to 58.8%, whereas in sporadic MPM cases it varied from 8.2% to 17.6% in patients with 2 and 3 or more melanomas, respectively. The microphthalmia-associated transcription factor E318K mutation accounted for 3% of MPM cases altogether.

LIMITATIONS

The study was hospital based, not population based. Rare novel susceptibility genes were not tested.

CONCLUSION

Italian patients who developed 2 melanomas, even in situ, should be referred for genetic counseling even in the absence of family history.