Epidemiology of Cutaneous Melanoma

  • The incidence of invasive cutaneous melanoma continues to be a major public health concern in the United States:
    • Of concern, the rate of melanoma has risen about 3% per year in the United States over the past few decades
  • Estimated incidence rates of new melanomas in 2021:
    • 106,110:
      • Men 62,260
      • Women 43,850
  • Estimated mortality rate for melanoma in the year 2021:
    • 7,180 people are expected to die of melanoma:
      • Men 4,600 men
      • Women 2,580 women
  • Melanoma remains more than 20 times more common in:
    • Whites than in African Americans
  • Overall, the lifetime risk of being diagnosed with melanoma is about:
    • 2.5% (1 in 40) for whites
    • 0.1%(1 in 1,000) for blacks
    • 0.5% (1 in 200) for Hispanics
  • The incidence of melanoma has been increasing faster than that of nearly any other cancer over the last 30 years
  • The major environmental risk factor:
    • Exposure to ultraviolet (UV) radiation:
      • Is reflected in geographic and ethnic patterns of melanoma rates
  • There have also been changes in the distribution and stage of melanoma at diagnosis:
    • With an overall trend toward thinner tumors:
      • Particularly among any patients with T1 / T2 melanomas:
        • While the opposite trend is seen among patients with thick, T4 lesions
  • Etiology and Epidemiology of Cutaneous Melanoma:
    • Cutaneous melanoma originates from melanocytes within the epidermal layer of the skin
    • Although these melanocytes represent a heterogeneous group of cells within the body:
      • They all share a common place of origin:
        • The neural crest, and the ability to produce melanin
    • In humans:
      • Melanin acts as the primary determinant of skin color and provides a layer of protection from ultraviolet (UV) radiation
  • Risk factors for the development of cutaneous melanoma include:
    • Sun exposure
    • Blistering sunburns
    • Fair complexion
    • Family history
    • Increasing age
    • Previous melanoma
    • Dysplastic nevi
  • Although UV radiation is a critical factor in the development of most melanoma:
    • It can occur in unexposed areas of the skin:
      • Such as the perineum, palms of the hands, and soles of the feet
  • However, most melanomas start on the:
    • Trunk in men and on the legs in women
  • Cutaneous melanoma is not the most common form of skin cancer:
    • But presents a considerable health burden as the incidence of disease continues to increase rapidly for both sexes
  • In the United States:
    • There is a higher rate of melanoma in men than in women:
      • But this tends to vary by age:
        • With men more at risk after the age of 50 years
  • Despite the rising rates of melanoma:
    • The prognosis remains excellent for those diagnosed and treated early:
      • With surgery providing the best form of cure for those with early-stage disease
  • Cutaneous malignancies constitute the most commonly diagnosed cancers in the United States of America (USA):
    • More than half of all cancers diagnosed each year
    • In the USA, approximately 1.2 million to 1.4 million cases of skin cancer are diagnosed annually
    • The most common skin cancer types are:
      • Basal cell carcinoma (BCC)
      • Squamous cell carcinoma (SCC)
      • Melanoma:
        • The incidence is increasing dramatically:
          • At an overall rate of 33% for men and 23% for women from 2002 to 2006:
            • About 2.6% per year
        • These estimates for new cases may represent a substantial underestimation because many superficial and in-situ melanomas treated in the outpatient setting are not reported
        • Approximately 8000 patients will be found to have metastatic melanoma at the time of diagnosis
        • Cutaneous melanoma accounts for 4% of all skin cancer diagnosis:
          • But accounts for 75% of skin cancer deaths
        • The age-adjusted incidence of invasive melanoma in the USA:
          • Increased from approximately 4 per 100,000 to 18 per 100,000 in white males between 1973 and 1998
          • The age-adjusted incidence of invasive melanoma in the USA increased to 21.1 per 100,000 in white males between 2011 and 2015
        • The incidence of melanoma continues to increase dramatically:
          • Melanoma is increasing in men more rapidly than any other malignancy and, in women more rapidly than any other malignancy except lung cancer:
            • This disturbing increase can be ascribed to prevailing social attitudes toward sun exposure
  • Recently, The Cancer Genome Atlas (TCGA) program performed DNA-, RNA-, and protein-based analysis of 333 primary and / or metastatic melanomas to catalog the most frequently encountered somatic alterations in cutaneous melanoma:
    • Using these data, cutaneous melanoma was then divided into four genomic subtypes:
      • BRAF
      • RAS
      • NF1
      • Triple-WT
    • The BRAF subtype is the largest genomic subtype:
      • Whereas RAS and NF1 are described as the second and third major subtypes, respectively
    • Although these first three subtypes are defined by their name-specific mutations:
      • Triple-WT subtype is defined as a:
        • Heterogeneous subgroup characterized by:
          • A lack of BRAF, RAS, or NF1 mutations
    • Clinically, BRAF subtypes were:
      • Younger than patients in the other subtypes:
        • Whereas those in the NF1 subtype were older
    • BRAF, RAS, and NF1 subtypes were noted to harbor a UV signature:
      • Defined as a high fraction of cytosine to thymine transitions at dipyrimidine sites:
        • In over 90% of the samples:
          • Compared with only 30% of the Triple-WT samples
    • These distinct genomic classifications provide a framework for identification of potential therapeutic targets and predictive biomarkers
  • Risk Factors for developmenting melanoma:
    • Pigment characteristics are important determinants of melanoma susceptibility:
      • There is an inverse correlation between melanoma risk and skin color that goes from lightest skin to darkest skin:
        • Melanoma occurs infrequently in skin of color:
          • Suggesting that skin pigment plays a protective role
        • Melanoma is 10 to 20 times more common in whites, and 6 to 7 times more common in Hispanics than in African Americans (AA)
    • Fair complexion:
      • Fitzpatrick skin photo-type I and II
    • Blue or green eyes
    • Blond or red hair
    • Freckling
  • A recent meta-analysis reported, that in contrast with people with Fitzpatrick skin photo-type IV:
    • Those with Fitzpatrick skin photo-type I are at more than double (2.27 times) the risk, photo-type II at double (1.99 times) the risk, and photo-type IIIa 35% increased risk for developing malignant melanoma
  • People with red / red – blonde hair:
    • Have triple the malignant melanoma risk compared to dark-haired people
  • People with blond hair:
    • Are at double the risk
  • People with light brown hair:
    • Are at 46% increased risk
  • Individuals with freckles:
    • Have double (1.99 times) the risk of malignant melanoma, as opposed to people without freckles:
      • These individuals with freckles have increased malignant melanoma risk:
        • Irrespective of the number of moles they have
  • Individuals with blue / green-blue / green-grey eyes:
    • Are at increased risk of basal cell carcinoma (BCC):
      • The risk for melanoma is less well known

#Arrangoiz #CancerSurgeon #SurgicalOncologist #HeadandNeckSurgeon #Melanoma #SkinCancer #CASO #CenterforAdvancedSurgicalOncology

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