Melanoma in Non-Caucasian Populations

Real-world post-deployment performance of a novel machine learning-based digital health technology for skin lesion assessment and suggestions for post-market surveillance

Introduction

Deep Ensemble for Recognition of Malignancy (DERM) is an artificial intelligence as a medical device (AIaMD) tool for skin lesion assessment.

Methods

We report prospective real-world performance from its deployment within skin cancer pathways at two National Health Service hospitals (UK) between July 2021 and October 2022.

Results

A total of 14,500 cases were seen, including patients 18-100 years old with Fitzpatrick skin types I-VI represented. Based on 8,571 lesions assessed by DERM with confirmed outcomes, versions A and B demonstrated very high sensitivity for detecting melanoma (95.0-100.0%) or malignancy (96.0-100.0%). Benign lesion specificity was 40.7-49.4% (DERM-vA) and 70.1-73.4% (DERM-vB). DERM identified 15.0-31.0% of cases as eligible for discharge.

Discussion

We show DERM performance in-line with sensitivity targets and pre-marketing authorisation research, and it reduced the caseload for hospital specialists in two pathways. Based on our experience we offer suggestions on key elements of post-market surveillance for AIaMDs.

Racial and Ethnic Health Disparities in Dermatology

Health disparities are differences in health or disease incidence, prevalence, severity, or disease burden that are experienced by disadvantaged populations. Their root causes are attributed in large part to socially determined factors, including educational level of attainment, socioeconomic status, and physical and social environments. There is an expanding body of evidence documenting differences in dermatologic health status among underserved populations. In this review, the authors highlight inequities in outcomes across 5 dermatologic conditions, including psoriasis, acne, cutaneous melanoma, hidradenitis suppurativa, and atopic dermatitis.

The Social Determinants of Health and Their Impact on Dermatologic Health, Part 1: The Social Determinants of Health and Their Dermatologic Implications

The social determinants of health (SDoH) have significant influences on health and lead to health disparities in a variety of complex and intersecting ways. They are the nonmedical factors that must be addressed to improve health outcomes and achieve greater health equity. They are shaped by the structural determinants of health and impact individual socioeconomic status as well as the health of entire communities. Part 1 of this 2-part review aims to shed light on how the SDoH impact health and their specific implications on dermatologic health disparities.

Chronic Polymicrobial Infectious Melanonychia Striata

CASE

A 62-year-old man presented with a 10-year history of isolated melanonychia striata of his dominant thumb. Surgical biopsy ruled out subungual melanoma but revealed foreign plant material causing chronic infectious melanonychia from multiple pathogens, including Pseudomonas aeruginosa, Escherichia coli, and Candida spp. After removal of the nail plate and thorough debridement, the melanonychial streak resolved completely at 12 months of follow-up.

CONCLUSION

Bacterial infection is a rarely reported cause of melanonychia, and in addition to surgical pathologic specimens, intraoperative fungal and bacterial cultures should always be obtained for accurate diagnosis of melanonychia striata.

Variations in genetics, biology, and phenotype of cutaneous disorders in skin of color - Part I: Genetic, biologic, and structural differences in skin of color

Skin of color (SOC) populations include those who identify as Black/African, Hispanic/Latinx, Asian/Pacific Islander, American Indian/Native Alaskan, Indigenous Australian, Middle Eastern, biracial/multiracial, or non-White; this list is far from exhaustive and may vary between and within cultures. Recent genetic and immunological studies have suggested that cutaneous inflammatory disorders (atopic dermatitis, psoriasis, and hidradenitis suppurativa) and malignancies (melanoma, basal cell carcinoma, and cutaneous T-cell lymphoma) may have variations in their immunophenotype among SOC. Additionally, there is growing recognition of the substantial role social determinants of health play in driving health inequalities in SOC communities. It is critically important to understand that social determinants of health often play a larger role than biologic or genetic factors attributed to "race" in health care outcomes. Herein, we describe the structural, genetic, and immunological variations and the potential implications of these variations in populations with SOC. This article underscores the importance of increasing the number of large, robust genetic studies of cutaneous disorders in SOC to create more targeted, effective therapies for this often underserved and understudied population. Part II of this CME will highlight the clinical differences in the phenotypic presentation of and the health disparities associated with the aforementioned cutaneous disorders in SOC.

Associations Between Race/Ethnicity, Language, and Enrollment on Cancer Research Studies

PURPOSE

The objective of this study was to determine whether differences in patients' race/ethnicity, preferred language, and other factors were associated with patient enrollment in oncology research studies.

PATIENTS AND METHODS

We conducted a retrospective cross-sectional analysis of all adults (>18 and ≤90) seen at a large, metropolitan cancer center from 2005 to 2015, examining if enrollment to a research study, varied by race/ethnicity, preferred language, comorbidities, gender, and age.

RESULTS

A total of 233 604 patients were available for initial analysis. Of these, 93 278 (39.9%) were enrolled in a research protocol (therapeutic and non-therapeutic studies). Patients who self-reported their race/ethnicity as Native, Other, Unknown, or Refuse to Answer were less likely to be enrolled on a study. Patients with one or more comorbidities, and those whose preferred language was English, were more likely to be enrolled on a research study. A logistic regression model showed that, although Non-Hispanic Black patients were more likely to have one or more comorbidities and had a higher proportion of their subset selecting English as their preferred language, they were less likely to be enrolled on a study, than our largest population, Non-Hispanic/White patients.

CONCLUSIONS

We identified differences in research study enrollment based on preferred language, and within race/ethnicity categories including Native-Populations, Other, Unknown or Refuse to Answer compared to Non-Hispanic/White patients. We also highlighted the lower odds of enrollment among Non-Hispanic/Black patients, in the setting of factors such as comorbidities and English language preference, which were otherwise found to be positive predictors of enrollment. Further investigation is needed to design targeted interventions to reduce disparities in oncology research study enrollment, with particular focus on language diversity.

Benefit and toxicity of programmed death-1 blockade vary by ethnicity in patients with advanced melanoma: an international multicentre observational study

BACKGROUND

Programmed cell death receptor-1 (PD-1) monotherapy is a standard treatment for advanced cutaneous melanoma, but its efficacy and toxicity are defined in white populations and remain poorly characterized in other ethnic groups, such as East Asian, Hispanic and African.

OBJECTIVES

To determine the efficacy and toxicity of PD-1 monotherapy in different ethnic groups.

METHODS

Clinical data for patients with unresectable or advanced melanoma treated with anti-PD-1 monotherapy between 2009 and 2019 were collected retrospectively from five independent institutions in the USA, Australia and China. Tumour response, survival and immune-related adverse events (irAEs) were compared by ethnicity (white vs. East Asian/Hispanic/African) across different melanoma subtypes: nonacral cutaneous (NAC)/unknown primary (UP) and acral/mucosal/uveal.

RESULTS

In total, 1135 patients were included. White patients had significantly higher objective response rate (ORR) [54%, 95% confidence interval (CI) 50-57% vs. 20%, 95% CI 13-28%; adjusted P < 0·001] and longer progression-free survival (14·2 months, 95% CI 10·7-20·3 vs. 5·4 months, 95% CI 4·5-7·0; adjusted P < 0·001) than East Asian, Hispanic and African patients in the NAC and UP subtypes. White ethnicity remained independently associated with a higher ORR (odds ratio 4·10, 95% CI 2·48-6·81; adjusted P < 0·001) and longer PFS (hazard ratio 0·58, 95% CI 0·46-0·74; adjusted P < 0·001) in multivariate analyses after adjustment for age, sex, primary anatomical location, metastasis stage, baseline lactate dehydrogenase level, mutational status and prior systemic treatment. White and East Asian/Hispanic/African patients shared similar ORR and progression-free survival in acral/mucosal/uveal melanomas. Similar melanoma-subtype-specific ethnic discrepancies were observed in complete response rate and overall survival. White patients had higher rates of gastrointestinal irAEs but lower rates of endocrine, liver and other rare types of irAEs. These differences in irAEs by ethnicity were not attributable to varying melanoma subtypes.

CONCLUSIONS

Ethnic discrepancy in clinical benefit is specific to melanoma subtype, and East Asian, Hispanic and African patients with NAC and UP melanomas have poorer clinical benefits than previously recognized. The ethnic discrepancy in toxicity observed across different melanoma subtypes warrants an ethnicity-based irAE surveillance strategy. More research is needed to elucidate the molecular and immunological determinants of these differences. What is already known about this topic? There is a great difference in response to immunotherapy between different subtypes of melanoma (cutaneous, mucosal, acral and uveal) in patients with advanced disease. What does this study add? Our data show for the first time that there are differences between different ethnic groups in terms of both response and toxicity to immunotherapy beyond the well-appreciated discrepancies due to melanoma subtype.

Prognostic Factors and Clinical Outcomes of Clinical Node-Negative Cutaneous Malignant Melanoma Patients: An Asian Single Institute Study

INTRODUCTION

Cutaneous malignant melanoma is notorious for its aggressive behavior and relatively poor outcome compared with other common skin malignancies. Acral lentiginous melanoma (ALM) accounts for at least 50% of melanoma in the Asian population and has a significantly lower survival rate. However, previous studies of the prognostic factors of melanoma-specific survival were all conducted from Western institutions. Here, we performed a retrospective analysis to investigate this issue.

METHODS

Fifty patients diagnosed as having clinical node-negative cutaneous malignant melanoma who underwent sentinel lymph node (SLN) biopsy at Taipei Veterans General Hospital between January 2007 and December 2018 were enrolled. Patient demographics, tumor characteristics, and lymph node characteristics were evaluated by chart review.

RESULTS

Eighty-two percent of the melanoma in the sample population was ALM. Twelve patients (24.0%) presented at least 1 metastatic sentinel node, and the average number of retrieved SLNs was 3. Of the patients with positive SLNs who proceeded to completion lymph node dissection, only 2 (16.7%) had metastatic nonsentinel nodes (NSNs). The average follow-up time for all patients was 45 months. Recurrence and melanoma-specific death occurred in 21 patients (42.0%) and 15 patients (30.0%), respectively. Melanoma-specific survival was significantly lower in patients with ulcerative lesions (P = 0.005) and more metastatic SLNs (P = 0.036). The overall morbidity rate of completion lymph node dissection was 66.7%.

CONCLUSIONS

The presence of ulcerations and number of metastatic SLNs were the most important prognostic factors in this ALM-dominant Asian cohort. Among patients with clinically negative nodes but positive SLNs, less than one-fourth of patients harbored metastatic NSNs. Completion lymph node dissection carries a relatively high risk of morbidity; therefore, further research regarding predictors of positive NSNs in the Asian population is necessary.

Clinical and molecular features of subungual melanomas are site-specific and distinct from acral melanomas

Subungual melanomas (SUM) arise beneath the nails of the hands and feet, and account for 0.7-3.5% of all malignant melanomas. Most studies include SUM in the category of acral melanoma, but understanding the specific features of SUM is critical for improving patient care. In this study, we performed a site-specific comparison of the clinical and molecular features between 54 cases of SUM and 78 cases of nonsubungual acral melanoma. Compared to patients with acral melanoma, patients with SUM were younger at diagnosis, had a higher prevalence of primary melanomas on the hand, and had more frequent reports of previous trauma at the tumor site. SUM was deeper than acral melanoma at diagnosis, which correlated with an increased frequency of metastases. Analysis of common melanoma driver genes revealed KIT and KRAS mutations were predominantly found in SUM, whereas BRAF and NRAS mutations occurred almost exclusively in acral melanoma. We also discovered molecular differences in the cell cycle pathway, where CDK4/CCND1 amplifications were more frequent in SUM and CDKN2A/B loss occurred mostly in acral melanoma, and in the PI3K/mTOR pathway, where RICTOR amplification and TSC1 K587R mutations were exclusively in SUM and PTEN loss and AKT1 mutations were exclusively in acral melanoma. Comparison of hand versus foot tumors revealed more frequent ulceration of SUM foot tumors, which correlated with more distal metastases and poorer overall survival. In summary, we find SUM are both clinically and molecularly distinct from acral melanoma, and our data suggest KIT, CDK4/6, and mTOR inhibitors may be particularly relevant and effective treatments for patients with SUM.

The impact of demographics, socioeconomics, and health care access on melanoma outcomes

Disparities in melanoma care exist in the United States. Disparities in provider type, patient demographics, place of residence, insurance status, socioeconomic status, race/ethnicity, and age impact melanoma outcomes. Melanomas detected by dermatologists are thinner, at an earlier stage, and have better survival outcomes compared with detection by primary care providers or patients. Lower socioeconomic status, race/ethnicity, and place of residence are associated with decreased access to or use of dermatologists, or both, and more advanced melanomas at diagnosis. Additionally, uninsured and publicly insured individuals are more likely to present with late-stage melanomas, resulting in worse outcomes. This review provides a comprehensive overview of how structural and patient-level characteristics influence melanoma outcomes in order to inform clinical care and health care policy as it relates to addressing gaps in melanoma care.

A novel RNA sequencing-based prognostic nomogram to predict survival for patients with cutaneous melanoma: Clinical trial/experimental study

BACKGROUND

Plenty of evidence has suggested that long non-coding RNAs (lncRNAs) have played a vital part may act as prognostic biomarkers in a variety of cancers. The aim of this study was to screen survival-related lncRNAs and to construct a lncRNA-based prognostic model in patients with cutaneous melanoma (CM).

METHODS

We obtained lncRNAs expression profiles and clinicopathological data from the Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) databases. A lncRNA-based prognostic model was established in training set. The established prognostic model was evaluated, and validated in the validation set. Then, a prognostic nomogram combining the lncRNA-based risk score and clinicopathological characteristics was developed in training set, and assessed in the validation set. The accuracy of the model was evaluated by the discrimination and calibration plots.

RESULTS

A total of 212 lncRNAs were identified to be differentially expressed in CM. After univariate analysis, LASSO penalized regression analysis, and multivariate analysis, 3 lncRNAs were used to construct risk score model. The proposed risk score model could divide patients into high-risk and low-risk groups with significantly different survival in both training set and validation set. The ROC curve showed good performance in survival prediction in both sets. Furthermore, the nomogram for predicting 3-, 5-, and 10-year OS was established based on lncRNA-based risk score and clinicopathologic factors. The prognostic accuracy of the risk model was confirmed by the discrimination and calibration plots in both training set and validation set.

CONCLUSIONS

We established a novel three lncRNA-based risk score model and nomogram to predict overall survival of CM. The proposed nomogram may provide information for individualized treatment in CM patients.

Clinical Presentations of Melanoma in African Americans, Hispanics, and Asians

BACKGROUND

Skin cancer has traditionally been studied in Caucasian skin. Although it does occur with increased relative frequency in Caucasians, patients with skin of color suffer from elevated morbidity and mortality when diagnosed with skin cancer.

OBJECTIVE

To detail the unique demographic, clinical, and genetic features of melanoma in patients with skin of color, including Hispanic, African American, and Asian patients.

MATERIALS AND METHODS

A PubMed search was conducted spanning dates 1947 to June 2017. A total of 246 articles were screened, from which 69 were included in this review.

RESULTS

Relative to Caucasians, melanoma has unique demographic, clinical, and genetic features in African Americans, Hispanics, and Asians that include gender and subtype predominance.

CONCLUSION

Familiarization with these unique presentations of skin cancer in skin of color is imperative to accurate identification and treatment of cutaneous malignancies in these populations and ultimately to improved disease-related outcomes.

Subungual Melanoma

Subungual melanoma is a rare form of melanoma that presents a unique set of challenges largely based on the complex anatomy of the nail unit. Subungual melanoma often first appears with longitudinal melanonychia. Thus, practitioners must have a high clinical suspicion in any patient with longitudinal melanonychia and a low threshold for a biopsy. The "ABCDEF" guide can be a useful tool to aid in screening any lesion of the nail bed. The authors recommend that biopsies of the nail unit be performed by a surgeon with an in-depth understanding of the pathoanatomy of subungual melanoma.

Epidemiological and histopathological profile of malignant melanoma in Malawi

Background

Studies on malignant melanoma have largely focused on Caucasian populations due to higher incidence in lighter-skinned individuals. While there is a well developed body of literature describing melanoma in African-Americans, much less is known about melanoma in black Africans. Prior reports have suggested that it is reportedly extremely rare in black Africans who are considered to mostly have the acral lentiginous subtype. However, an accurate understanding of melanoma in this part of the world is hindered by the very limited nature of prior publications. The aim of this study was to determine the epidemiological profile, anatomical distribution and histopathological features of melanoma presenting in Africans at a tertiary referral hospital in Malawi.

Methods

This is a retrospective study that characterized melanoma cases diagnosed from January 2012 to December 2017, at a cancer referral centre in Malawi. All confirmed, malignant melanoma cases during the study period were retrieved. Data abstracted included age, sex, anatomic site and whether it was a primary or metastatic site. Breslow thickness in millimetres, Clark level of invasion, presence of ulceration and melanoma subtype were also evaluated.

Results

One hundred thirty-two cases were included in the study, 81 (61%) were female and 26 (20%) were from a metastatic site. The mean age was 57 years (sd = 15) with the majority in the age group 60–69 years. Males presented at an older age than females. Ninety five percent of cutaneous melanomas were located on acral sites, most commonly the foot (87%) and the most common histopathological subtype was acral lentiginous. Eighty four percent presented with a Breslow thickness over 4 mm (median 9 mm).

Conclusion

Our study shows that malignant melanoma occurs in black people in Malawi and may be an under-appreciated malignancy. While long term clinical follow-up was not available, most patients presented at late stages of the disease, supporting a poor prognosis. These results suggest that increased awareness of melanoma in black Africans and earlier intervention may have meaningful impacts on outcomes and survival.

Skin cancers in patients of skin phototype V or VI with xeroderma pigmentosum type C (XP-C): A retrospective study

BACKGROUND

Xeroderma pigmentosum (XP) is a rare genetic disease comprising 7 subgroups, A to G, all of which are associated with early onset of several forms of skin cancer. Our main objective was to determine the prevalence of skin cancers in a cohort of dark-skinned XP-C patients in Mayotte.

PATIENTS AND METHODS

A single-centre cohort consisting of all XP patients was followed in the island of Mayotte from December 2015 to May 2017 by dermatologists from the University Hospital of Saint-Denis (Reunion) during the course of dermatological missions.

RESULTS

Eighteen patients of median age 12.9 years (7 female/11 male) belonging to 14 families were included. All had XP-C and carried the same mutation. Median age at clinical diagnosis of XP was 1.8 years. A total of 144 skin cancers (94 squamous cell carcinomas [SCC], 30 basal cell carcinomas [BCC], 14 melanomas, 5 sarcomas and 1 sarcomatoid carcinoma) were observed in 11 of the 18 patients (61%). Eleven patients (61%) had at least 1 SCC, 6 (33%) had at least 1 BCC, 6 (33%) had at least 1 melanoma, and 4 (22%) had at least 1 sarcoma. In all, 95.5% of the cancers occurred in light-exposed skin areas. Median age was 5.4 years for the initial cancer and 6.4 years for the second. SCCs and sarcomas occurred earlier than CBCs and melanomas (P<0.0001). All patients had mild to severe poikiloderma and presented photophobia, and 50% had pigmented palmoplantar lesions. One-third had oral mucosal involvement while 78% had ocular or palpebral lesions. Nail and hair involvement was recorded in 17% of patients. The median sun protection score (evaluated on a 7-item scale) was 6/7. The median score on the quality-of-life questionnaire (DLQI) was 4/30. Severity of poikiloderma was significantly correlated with the occurrence of skin cancers.

DISCUSSION AND CONCLUSION

Our cohort showed a high prevalence of skin cancer in XP-C patients of phototype V and VI exposed to UV radiation in a tropical region. SCCs were the most common tumours. The prevalence of melanoma was high, with major risk compared to controls of the same skin phototype. In addition, we found a high prevalence of sarcomas (5 patients). Initial cancers occurred early (5.4 years) compared to data from the literature, and SCCs and sarcomas occurred significantly sooner than melanomas and BCCs.

Prognostic factors of patients with spinal malignant melanoma after surgical intervention: a case series of 21 patients and literature review

BACKGROUND

Spinal malignant melanoma (SMM) is a rare type of tumor that can cause nerve roots or spinal cord compression. Patients often suffer from fierce pain and paralyzation. And the estimated survival time were less than 6 months. Surgical interventions to remove the tumor and decompress the nearby nerve roots and spinal cord are effective management. Unfortunately, there lack a thorough and persuasive surgical guideline that specifically aims for this disease. It is necessary to obtain some clinical prognostic factors that predict the recurrence rate and overall survival (OS) of patients with SMM who underwent surgical interventions.

METHODS

21 patients with SMM who underwent surgical intervention were retrospectively reviewed. Related patients factors, treatment factors and tumor factors were acquired and subjected into survive analyses using Kaplan-Meier method and the log-rank test. Further Cox proportional hazards model was used to identify independent prognostic factors. Literature regarding surgical interventions on SMM patients were reviewed and summarized as well.

RESULTS

Surgical approach total en-bloc spondylectomy (TES/Piecemeal) (p = 0.015, B 0.029, 95%CI 0.002-0.508), preoperative Frankel grade (A-C/D-E) (p = 0.021, B 15.041, 95%CI 1.492-151.669) and tumor metastases (Yes/No) (p = 0.013, B 16.667, 95%CI 1.805-153.897) are independent prognostic factors for recurrence free survival (RFS). Preoperative Frankel grade (A-C/D-E) (p = 0.031, B 10.676, 95%CI 1.241-91.877) is independent prognostic factors for OS. 12 literatures have been reviewed, including 11 case reports and one retrospective study.

CONCLUSIONS

Surgical interventions for patients with SMM are beneficial. Surgical approach (TES/piecemeal), tumor origin (primary/metastasis) and preoperative Frankel grade (A-C/D-E) are independent risk factors in predicting RFS. Preoperative Frankel grade (A-C/D-E) is independent prognostic factor in predicting OS.

Skin cancer risk assessment in dark skinned immigrants: the role of social determinants and ethnicity

OBJECTIVES

Dark-skinned people have a lower incidence rate of skin cancer, in particular melanoma, which is detected at more advanced stages leading to poorer prognoses and long-term outcomes compared to whites. The gap in survival is due to some difficulty in melanoma detection, lack of attention from doctors and awareness by patients. This study aims to assess skin cancer risk awareness in dark-skinned immigrants and to determine the influence of socioeconomic factors and ethnic origin on behaviors.

DESIGN

This is a cross-sectional health facility based study carried out in a 12-month period. A semi-structured questionnaire to assess skin cancer risk awareness and a dermatological examination was offered to dark-skinned immigrants consecutively attending the dermatology department of the National Institute for Health, Migration and Poverty in Rome.

RESULTS

147 dark-skinned immigrants were enrolled, of which 54.4% were males, coming from Africa (53.1%). They were mainly young, aged 18-34 (56.5%). The level of education and length of stay in Italy was significantly related to the awareness about skin cancer: people with a high educational level (OR: 8.1 95% CI: 3.2-23.4) or immigrated more than 4 years before the interview (OR: 2.1 95% CI: 1.0-4.4) have a greater knowledge about skin cancer.

CONCLUSIONS

Education level is the strongest predictive factor of skin cancer awareness, whereas cultural behaviours and personal experience of sunburns are the main factors determining sunlight avoidance. Health promotion programs targeting immigrants must consider cultural differences related to ethnicity and country of origin, and adopt a transcultural approach.

Acral melanoma: correlating the clinical presentation to the mutational status

Acral lentiginous melanoma (ALM) is the most common type of malignant melanoma (MM) in Asians, Afro-Americans and Middle-Easterners. It represents 1.5-10% of all MM cases, being the most common histological type of MM arising on palms, soles and nail apparatus, which is more generically defined as acral MM. To date no risk factors have been officially established, however a history of trauma may be involved in the pathogenesis of acral MM. This shows heterogeneous clinical features and frequently presents with advanced stage and aggressive behavior, often as a result of misdiagnosis or delayed identification. Dermoscopy is helpful for an early diagnosis of ALM: the most characteristic dermoscopic patterns are the parallel ridge and the irregular diffuse pigmentation. On histopathology ALM displays a lentiginous growth pattern, with melanocytes arranged as solitary units along the basilar epidermis, without notable pagetoid growth in the early stage. Not all acral MMs present a lentiginous pattern: superficial spreading melanoma and nodular melanoma patterns are also possible. Novel studies investigating the biologic characteristics of acral MM reported variable results: the overall mutational rates ranged respectively between 8.5% and 23% for KIT, between 3.6% and 33.3% for BRAF and between 3% and 47% for NRAS in ALMs. Increasing attention has been recently given to other genes, such as telomerase reverse transcriptase, platelet-derived growth factor receptor alfa and cyclin D1. Larger molecular investigations urge to describe the molecular profile of acral MM, to allow the development of specific targeted therapies.

Incidence of cutaneous malignant melanoma in Iranian provinces and American states matched on ultraviolet radiation exposure: an ecologic study

OBJECTIVES

Ultraviolet radiation (UVR), with UVB and UVA as the relevant components, is a risk factor for melanoma. Complete ascertainment and registration of melanoma in Iran was conducted in five provinces (Ardabil, Golestan, Mazandaran, Gilan and Kerman) during 1996-2000. The aim of our study was to compare population-based incidence data from these provinces with rates in the United States (US) while standardizing ambient UVR.

METHODS

Population-based rates representing all incident cases of melanoma (1996-2000) across the five Iranian provinces were compared to rates of melanoma among white non-Hispanics in the US. Overall age-standardized rates (ASR) for Iran and the US (per 100,000 person-years adjusted to 2000 world population) and standardized rate ratios (SRR) were calculated. We measured erythemally-weighted average solar UVR exposures (with contributions from both UVB and UVA range) of the five Iranian provinces using data from NASA's Total Ozone Mapping Spectrometer and selected five US states (Kentucky, Utah, Texas, Oklahoma, and Hawaii) with matching UVR exposure to each province. Incidence rates of melanoma during 1996-2000 in each Iranian province were compared to rates among white non-Hispanics in its UVR-matched US state.

RESULTS

The overall male and female ASRs of melanoma were 0.60 (95%CI: 0.56-0.64) and 0.46 (95%CI: 0.42-0.49), respectively, for Iran and 22.78 (95%CI: 22.42-23.14) and 16.61 (95%CI: 16.30-16.92) for the US. SRRs of melanoma comparing US to Iran were 37.97 (95%CI: 35.78-40.29) for males and 36.11 (95%CI: 33.69-38.70) for females, indicating significantly higher incidence in the US. ASRs and age-specific rates of melanoma for both genders were significantly lower in each Iranian province compared to its UVR-matched US state.

CONCLUSION

The markedly lower incidence rates of melanoma in Iranian provinces with similar UVR exposures to US states underscore the need for additional comparative studies to decipher the influence of other extrinsic and intrinsic factors on the risk of this malignancy.

The MeLiM Minipig: An Original Spontaneous Model to Explore Cutaneous Melanoma Genetic Basis

Melanoma is the deadliest skin cancer and is a major public health concern with a growing incidence worldwide. As for other complex diseases, animal models are needed in order to better understand the mechanisms leading to pathology, identify potential biomarkers to be used in the clinics, and eventually molecular targets for therapeutic solutions. Cutaneous melanoma, arising from skin melanocytes, is mainly caused by environmental factors such as UV radiation; however a significant genetic component participates in the etiology of the disease. The pig is a recognized model for spontaneous development of melanoma with features similar to the human ones, followed by a complete regression and a vitiligo-like depigmentation. Three different pig models (MeLiM, Sinclair, and MMS-Troll) have been maintained through the last decades, and different genetic studies have evidenced a complex inheritance of the disease. As in humans, pigmentation seems to play a prominent role, notably through MC1R and MITF signaling. Conversely, cell cycle genes as CDKN2A and CDK4 have been excluded as predisposing for melanoma in MeLiM. So far, only sparse studies have focused on somatic changes occurring during oncogenesis, and have revealed major cytological changes and a potential dysfunction of the telomere maintenance system. Finally, the spontaneous tumor progression and regression occurring in these models could shed light on the interplay between endogenous retroviruses, melanomagenesis, and adaptive immune response.

Is UV an etiological factor of acral melanoma?

Ultraviolet (UV) radiation is a major environmental risk factor for melanoma, particularly among Caucasians. However, studies have generated conflicting results on the role of UV exposure in the development of acral melanoma, the most prevalent subtype of melanoma in non-Caucasians. In this review, we analyzed studies that have examined the relationship between acral melanoma and UV and show that acral melanoma has specific epidemiological and genetic characteristics, with a lower frequency or absence of UV-induced features. Therefore, we postulate that UV is probably not involved in the etiology of acral melanoma. However, further epidemiological and laboratory studies are required to fully address this controversial issue, which may lead to a better understanding of the pathogenesis and prevention of acral melanoma.

Acral Lentiginous Melanoma

Acral lentiginous melanoma (ALM) is a rare subtype of melanoma mainly arising on the palms, soles, and nail beds. ALM is the most common subtype of melanoma found in patients of Asian or African descent and tends to more advanced at presentation due to delays in diagnosis. Surgical treatment is difficult owing to the complexity and functional importance of the hands and feet and reconstruction after resection is usually needed. The prognosis for patients with ALM depends on stage of disease and tends to be worse than with other subtypes of melanoma. Newer treatment modalities such as immunotherapies and targeted agents are being tested in patients with advanced ALM with some promising preliminary results.

DNA Methylation Levels of Melanoma Risk Genes Are Associated with Clinical Characteristics of Melanoma Patients

In melanoma development, oncogenic process is mediated by genetic and epigenetic mutations, and few studies have so far explored the role of DNA methylation either as predisposition factor or biomarker. We tested patient samples for germline CDKN2A methylation status and found no evidence of inactivation by promoter hypermethylation. We have also investigated the association of clinical characteristics of samples with the DNA methylation pattern of twelve genes relevant for melanomagenesis. Five genes (BAP1, MGMT, MITF, PALB2, and POT1) presented statistical association between blood DNA methylation levels and either CDKN2A-mutation status, number of lesions, or Breslow thickness. In tumors, five genes (KIT, MGMT, MITF, TERT, and TNF) exhibited methylation levels significantly different between tumor groups including acral compared to nonacral melanomas and matched primary lesions and metastases. Our data pinpoint that the methylation level of eight melanoma-associated genes could potentially represent markers for this disease both in peripheral blood and in tumor samples.