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Skin Cancer

Causes of Skin Cancer

As with most cancers, doctors can’t tell you with certainty what caused your skin cancer. It’s a combination of genetic factors and factors in your environment. We know certain patients with certain genetic disorders are more likely to get skin cancers. A few of these disorders include:

  • Xeroderma pigmentosa
  • Nevoid basal cell syndrome (Gorlin Syndrome)
  • Cowden Syndrome
  • Familial melanoma/dysplastic nevus syndrome
  • Peutz-Jeghers Syndrome
  • Werner Syndrome
  • Muir-Torre Syndrome
  • Gardner Syndrome

Also, some acquired disorders or diseases can also increase the risk of getting skin cancer. These are mainly disorders that lower the body’s defenses (immune system). This includes:

  • Organ transplant patients on immune-suppressing medications
  • HIV-positive patients
  • Lymphoproliferative disorders

Still, it seems that ultraviolet radiation (such as from the sun) is the most important cause of skin cancer.

  • Ultraviolet radiation: At this time, researchers believe that when UV waves (mainly in the UVB spectrum) hit the cells of the skin, they cause mutations in the genes of the cells. Mutated skin cells can then grow uncontrollably. This is cancer. UV radiation may also make natural cancer-fighting cells in the skin less effective. Interestingly, lighter-skinned people are more likely to get NMSC than darker-skinned people. This may be related to how melanin (dark pigment) protects skin cells from UV damage. The Fitzpatrick classification system is commonly used to classify patients into different groups. Patients who have a lower Fitzpatrick classification are more likely to get NMSC caused by UV radiation than those in a higher Fitzpatrick classification.

Fitzpatrick Classification of Skin Type

Type I White, pale Always burns, never tans
Type II White, fair Usually burns, tans with difficulty
Type III White to light brown (common in US) Sometimes burns, sometimes tans
Type IV White to moderate brown, olive Rarely burns, tans easily
Type V Brown to dark brown Very rarely burns, tans very easily
Type VI Very dark brown to black Never burns, always tans

63_fitzpatrick_classes

But exposure to other risk factors (not just the sun) has also been linked to causing non-melanoma skin cancer:

  • Ionizing radiation
  • Coal tar
  • Asphalt
  • Arsenic ingestion

Finally, there are some skin lesions that doctors think are pre-cancerous lesions. These are growths that are not cancer but, if not removed, might turn into cancer. Examples of pre-cancerous lesions that can lead to NMSCs include:

  • Actinic keratoses
  • Keratoacanthoma
  • Bowen’s Disease

For melanoma, there is good evidence that many cancers come from dark lesions that have been there for a while. When these suddenly change, there is concern for melanoma. Examples of precursor lesions that are at increased risk of developing into melanoma include:

  • Congential nevi (especially if large)
  • Dysplastic nevi
  • Lentigo maligna

 

References

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3 Albores-Saavedra J, Batich K, Chable-Montero F, Sagy N, Schwartz AM, Henson DE. Merkel cell carcinoma demographics, morphology, and survival based on 3870 cases: a population based study. J Cutan Pathol. 2010:37:20-27.

4 LeBoit PE, Burg G, Weedon D, Sarasain A. (Eds.): World Health Organization. Classification of Tumours. Pathology and Genetics of Skin Tumours. IARC Press: Lyon 2006.

5 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Basal Cell and Squamous Cell Skin Cancers V.1.2014. © National Comprehensive Cancer Network, Inc 2014. All rights reserved. Accessed Jan. 22, 2014. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

6 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Melanoma V.3.2014. © National Comprehensive Cancer Network, Inc 2014. All rights reserved. Accessed Feb 12, 2014. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

7 Referenced with permission from The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Merkel Cell Carcinoma V.1.2014. © National Comprehensive Cancer Network, Inc 2014. All rights reserved. Accessed Jan. 22, 2014. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

8 Referenced with permission from the NCCN Guidelines for Patients®: Melanoma V.1.2013. © National Comprehensive Cancer Network, Inc 2013. All rights reserved. Accessed July 2, 2013. To view the most recent and complete version of the guideline, go online to www.nccn.org. NATIONAL COMPREHENSIVE CANCER NETWORK®, NCCN®, NCCN GUIDELINES®, and all other NCCN Content are trademarks owned by the National Comprehensive Cancer Network, Inc.

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21 Albores-Saavedra J, Batich K, Chable-Montero F, Sagy N, Schwartz AM, Henson DE. Merkel cell carcinoma demographics, morphology, and survival based on 3870 cases: a population based study. J Cutan Pathol. 2010:37:20.

22 Wang TS, Byrne PJ, Jacobs LK, Taube JM. Merkel Cell Carcinoma: Update and Review. 2011 Seminars in Cutaneous Medicine and Surgery: 30(1):48-56.