Facts About Skin Cancer

While sunbathing, walking, cooking, and swimming, the most significant organ in direct contact is the skin. It is equipped with a specific structure that protects against various dangers. Skin is divided into 3 layers: epidermis, dermis, and hypodermis. According to the function, the skin has been tasked with issues such as protection from harmful rays, adjusting the temperature balance, fighting pathogens, etc. Every layer of the epidermis has a different thickness depending on the region. These layers are stratum basale, spinosum, granulosum, lucidum, and corneum. Apart from these layers, the cells of the epidermis are keratinocytes (It makes up 95% of the epidermis and produces keratin protein.), melanocytes (It produces melanin pigment, which provides different skin colors and protects the skin from ultraviolet radiation.), Langerhans’ cells, and Merkel’s cells. The dermis, which is attached to the epidermis, consists of two layers: the papillary layer and the reticular layer. And finally, at the bottom is the hypodermis, also known as the subcutaneous fascia^1,2.

Despite all this organization, can our skin protect itself against diseases? Many environmental conditions threaten this structure. These threats can lead to various skin cancers. So, what does cancer mean before moving on to skin cancer? According to the National Cancer Institute (NCI); it’s a disease that causes cells in a particular part of the body to multiply and spread uncontrollably to the other parts of the body. Under normal conditions, a cell grows, dies, and divides to replace it with new cells. Under abnormal conditions, the cell divides when it shouldn’t. These cells can form tumors. They can be cancerous (malignant) or not cancerous (benign). Cancerous tumors can travel through different pathways in the body and form new tumors, this process is called metastasis. In sum, cancer is a genetic disease caused by certain changes to genes because of various reasons³.

What about Skin Cancer?

There are three main types of skin cancer. They get their name from skin cells. These include basal cell skin cancer (also called basal cell carcinoma (BCC)), squamous cell skin cancer (also called squamous cell carcinoma (SCC)), and melanocytes skin cancer (also called malignant melanoma). More typically, it can be divided into non-melanoma skin cancer and melanoma skin cancer.

With its therapeutic resistance and high propensity to metastasize, malignant melanoma is more deadly than other types⁶. As can be seen in the table above, it is the 4th most common type of cancer in the world. Once melanoma is metastatic, the prognosis is quite low. Therefore, early diagnosis is of great importance for effective treatment⁷.

Human skin contains sunlight-induced cancer-protective cells. But solar rays produce ultraviolet (UV) light that can penetrate well under the skin. And in this way, the DNA of the cells is damaged. If a mutation turns into an oncogene or inactivates the tumor suppressor gene, this causes a cell to multiply excessively. The sun’s radiation is strong enough to suppress the skin’s immune system and affect cell division.

So, how can it be understood that such a mutation is caused by the sun? According to a study, mutations originating from the sun leave a fingerprint in DNA. In this study, conducted in 1996, the p53 gene (“guardian of the genome⁸”) was selected to study. It was revealed that the mutation in the p53 gene is an important reason for this issue, especially among non-melanoma skin cancers. Treatments vary according to the patient’s age, gender, tumor location, and stage. These treatments mainly include chemotherapy, radiotherapy, immunotherapy, and surgical resection⁹.

The possibility of contracting this disease is an interesting topic. Because this is an issue that carries a significant risk of which race we are from. Skin cancer is less common in dark-skinned ethnic groups than in light-skinned Caucasians. SCC and malignant melanoma usually occur in areas that are not exposed to the sun. These areas include palms, soles, mucous membranes, and nail regions. SCC is most common in black people. In contrast, BCC is primarily caused by exposure to intense UV light. And it is most common in light-skinned ethnic groups¹⁰ (Caucasians, Japanese, Hispanics, etc.).

Indoor or outdoor tanning is also very threatening. It is essentially our body’s act of protecting us from deeper injury. Against UV rays from the sun or tanning beds, melanocyte cells produce melanin pigment and thus the skin color darkens. This is how skin tries to prevent further injury¹¹. Moreover, indoor tanning increases 75% of skin cancer risk before age 35. Some countries have banned indoor tanning already¹².

Conclusion

The biggest difference between this disease from other cancers is that you can check and notice your body. If there is a sore that does not heal for a long time, hurts, and looks abnormal, this is a symptom of skin cancer. With early detection, non-melanoma cancer types can be easily treated. For this reason, it is a great benefit to check the whole body at regular intervals. Even melanoma can be treated if the tumor has not grown sufficiently. Worldwide, strategies should be determined to prevent the increase in skin cancer, and more effective treatments are needed, especially for the type of melanoma⁷.

References:

1. Yousef H, Alhajj M, Sharma S. Anatomy, Skin (Integument), Epidermis. [Updated 2021 Nov 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470464/
2. Losquadro W. D. (2017). Anatomy of the Skin and the Pathogenesis of Nonmelanoma Skin Cancer. Facial plastic surgery clinics of North America, 25(3), 283–289. https://doi.org/10.1016/j.fsc.2017.03.001
3. What Is Cancer? – NCI https://www.cancer.gov/about-cancer/understanding/what-is-cancer
4. https://www.cancerresearchuk.org/about-cancer/skin-cancer/about-skin-cancer
5. Leffell, D. J., & Brash, D. E. (1996). Sunlight and Skin Cancer. Scientific American, 275(1), 52–59. http://www.jstor.org/stable/24993269
6. Kalal, B. S., Upadhya, D., & Pai, V. R. (2017). Chemotherapy resistance mechanisms in advanced skin cancer. Oncology reviews, 11(1).
7. Domingues, B., Lopes, J. M., Soares, P., & Pópulo, H. (2018). Melanoma treatment in review. ImmunoTargets and therapy, 7, 35–49. https://doi.org/10.2147/ITT.S134842
8. Raimundo, L., Ramos, H., Loureiro, J. B., Calheiros, J., & Saraiva, L. (2020). BRCA1/P53: Two strengths in cancer chemoprevention. Biochimica et Biophysica Acta (BBA)-Reviews on Cancer, 1873(1), 188339.)
9. Miller, K. D., Siegel, R. L., Lin, C. C., Mariotto, A. B., Kramer, J. L., Rowland, J. H., … & Jemal, A. (2016). Cancer treatment and survivorship statistics, 2016. CA: a cancer journal for clinicians, 66(4), 271-289.
10. Gloster Jr, H. M., & Neal, K. (2006). Skin cancer in skin of color. Journal of the American Academy of Dermatology, 55(5), 741-760.
11. Tanning and your skin – Skin Cancer Foundation   https://www.skincancer.org/risk-factors/tanning/
12. Wehner MR, Chren MM, Nameth D, et al. International prevalence of indoor tanning: a systematic review and meta-analysis. JAMA Dermatol 2014; 150(4):390-400. doi:10.1001/jamadermatol.2013.6896.

Figure References:

1. PDQ Cancer Genetics Editorial Board. Genetics of Skin Cancer (PDQ®): Health Professional Version. 2022 Jun 28. In: PDQ Cancer Information Summaries [Internet]. Bethesda (MD): National Cancer Institute (US); 2002-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK65895/
2. https://acsjournals.onlinelibrary.wiley.com/cms/asset/f4cabd44-5bfa-4f1b-a971-c2766a6a1bd4/caac21349-fig-0002-m.jpg
3. https://www.skincarenetwork.co.uk/skin-cancer-treatment/how-to-check-for-signs/

Inspector: Furkan EKER