What is skin cancer?
Skin cancer is a group of skin conditions in which there is an abnormal growth of pathological skin cells that have the ability to expand, invade, and spread to other parts of the body.
Every type has specific symptoms and characteristics. The main ones are squamous cell carcinoma, basal cell carcinoma, and melanoma.
In most cases —more than 90%— this cancer is caused by exposure to ultraviolet (UV) radiation from the sun. Also, this exposure has increased considerably due to the decrease in the thickness of the ozone layer, which used to protect us against these rays.
A common source of exposure to ultraviolet radiation is the use of tanning machines and tanning beds. The belief that tanned skin is more beautiful has considerably increased the cases of skin problems due to this overexposure to UV rays.
Besides, people with fair skin are at greater risk of developing skin cancer, as they are more sensitive to the harmful effect of ultraviolet radiation, as well as those with a deficient immune system. Finally, between 20 and 30% of melanoma cases develop from pre-existing moles.
Some of the most effective methods of preventing this disease are the use of sunscreen and avoid exposure to ultraviolet radiation. However, it is not yet known exactly whether these preventive measures are equally effective in all types of skin cancer.
Basal cells and squamous cells carcinomas are usually curable. The treatment involves surgical removal of the cancerous tissue, with or without chemo or radiation therapy. In the case of melanoma, the treatment may involve a combination of surgery, chemotherapy, and radiation therapy.
Types and symptoms
Skin cancer tends to develop in areas of the skin that are exposed to the sun, such as the face, scalp, chest, arms, or legs. However, it may also appear in other, less exposed areas.
As mentioned above, there are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma.
1. Basal cell carcinoma
This carcinoma type usually occurs in areas of the body that are continually exposed to the sun, such as the neck or face.
Signs revealing a possible basal cell cancer include the appearance of a small bump in the skin, or a flat spot or lesion —the same color as the skin— or in the form of a brown scar.
2. Squamous cell carcinoma
Cell growth occurs mostly in other areas that are usually exposed to the sun as well, such as the face, ears, and hands.
This carcinoma is more common in people with darker skin. It may also appear in other areas that are not directly exposed to ultraviolet radiation.
This type of cancer can also appear in the form of firm, red nodules or as a flat lesion characterized by a scaly, crusted surface.
3. Melanoma
Melanoma can develop anywhere in the body, either in a normal area or in a pre-existing mole that becomes cancerous.
This type of cancer occurs most often on the face or trunk, and on the legs in the case of women.
Melanoma can affect people of any skin tone, and its symptoms include:
A big brownish spot with darker spots.
A mole that changes color, size or that bleeds.
The appearance of a small lesion with irregular borders and red, blue, white or black parts and areas.
Dark lesions on the palms of the hands, soles of the feet, toes, or mucous membranes of the mouth, nose, vagina, or anus.
4. Other types
Other less common varieties of skin cancer include:
Kaposi's sarcoma: The development of cancer cells in the blood vessels of the skin.
Merkel-cell carcinoma: The appearance of firm, shiny nodules under the skin and hair follicles.
Sebaceous gland carcinoma: Hard, painless nodules that usually develop on the eyelid.
Causes
The origin of skin cancer is an error or mutation in the DNA of skin cells. Mutations cause cells to grow out of control and form a mass of cancer cells.
The main cause of DNA damage in skin cells is exposure to ultraviolet radiation. It is found in rays of sunlight and lights used in tanning beds.
However, exposure to ultraviolet rays would only explain the cancers that appear in those areas of the skin exposed to light. This indicates that there are certainly other factors that may contribute to an increased risk of this disease, such as some toxic substances or a condition that weakens the immune system.
Risk factors
There are some factors that could increase the risk of developing some type of skin cancer:
Very pale or fair skin
Tendency to sunburn
Excessive sun exposure
Sunny or high altitude climates
Having many freckles, moles, or precancerous skin lesions, such as actinic keratoses
Family medical history
Exposure to radiation or certain toxic substances
Treatment
Treatment options depend on the type of cancer, the size, depth, and location of the lesions.
In the case of a small carcinoma, it may require no treatment other than surgical removal and removal of damaged tissue.
If the disease is severe, additional treatment may be needed. These treatments usually include cryotherapy or tissue cryosurgery, in which the tissue is frozen with liquid nitrogen and removed. Radiotherapy or chemotherapy are also used.
References
Gallagher, R. P., Lee, T. K., Bajdik, C. D. & Borugian, M. (2010). Ultraviolet radiation. Chronic diseases in Canada, 29 (1): 51–56.
Jou, P. C., Feldman, R.J. & Tomecki, K. J. (2012). UV protection and sunscreens: what to tell patients. Cleveland Clinic journal of medicine. 79 (6): 427–436.
Dubas, L. E. & Ingraffea, A. (2013). Nonmelanoma skin cancer. Facial plastic surgery clinics of North America, 21(1): 43–53.
Saladi, R. N. & Persaud, A. N. (2005). The causes of skin cancer: a comprehensive review. Drugs of today, 41(1): 37–53.
Kanavy, H. E. & Gerstenblith, M. R. (2011). Ultraviolet radiation and melanoma. Seminars in Cutaneous Medicine and Surgery, 30(4): 222–228.