Ultraviolet radiation is mainly responsible for the development of skin cancer. Besides the sun, this radiation is also found in tanning booths. The effect of ultraviolet radiation on the skin is cumulative, i.e., even after cessation of exposure to the sun, skin changes can still manifest after years.
In this text we will talk specifically about the melanoma, the most serious type of skin cancer.
Melanin is a pigment produced by melanocytes, is responsible for our skin color, eyes and hair. When we are exposed to sunlight, melanocytes are stimulated to produce more pigment, causing the skin to become darker.
Melanoma is a malignant tumor which originates in the melanocytes, skin cells responsible for melanin production. Melanocytes are found mainly in the skin, however, are also present in eyes, gastrointestinal tract, meninges and oral and genital mucosa. This means that although the vast majority of melanomas are dealing with skin cancers, it may eventually emerge in the eyes and intestines, for example.
Melanoma accounts for only 4% of all types of skin cancer, however, it is the most serious and aggressive, it may cause metastases with great ease. Although it is not the most common type, about three quarters of deaths from skin cancer are caused by melanoma.
As one person has less melanin in their skin, the lower is their protection against the harmful effects of solar radiation. Redheads, blondes with blue eyes or freckles on the skin are more likely to develop melanoma. Those people who always burn in the sun and almost never get tanned are also at increased risk. Another sign of vulnerability is the presence of several dark spots or signs on the skin (called in medicine nevus). Persons who have over 50 moles on their body are more likely to develop melanoma.
Sun exposure is the main risk factor for any skin cancer, including melanoma. The standard time and cumulative sun exposure throughout life are associated with the type of skin cancer that a person can develop. The non-melanoma skin cancers occur in those people with high sun exposure throughout life, especially in emerging areas of exposed skin, such as face, hands and forearm. Since melanoma tends to occur in those individuals with less frequent exposure to sunlight, but high intensity, for example, those individuals with lighter skin end who catch sun in excess during holidays, leaving painful and extensive burn. These exhibits are sporadic, but intense, and are more dangerous when they occur during childhood and adolescence. Individuals with more than five episodes of excessive sun exposure with major burns have up to two times higher risk of developing melanoma later in life.
Other risk factors for melanoma:
Tanning: like natural sunlight, artificial tanning by ultraviolet light cameras at up to 75% increases the risk of melanoma, especially if used before 35 years.
Family history: If a relative of first degree (child, sibling or parent) has had melanoma, it means that you are also genetically more prone to have it.
Immunosuppression: People with weakened immune systems (AIDS patients, transplant or undergoing chemotherapy, for example) have a higher risk of developing melanoma.
Living in the tropics: people who live near the equator, especially if they have fair skin are at higher risk of developing melanoma. For Blacks and Hispanics this factor is not so important.
Endometriosis: no one knows exactly why, but women with a history of endometriosis are at increased risk for skin cancer like melanoma.
Parkinson: patients with Parkinson's disease also have a higher incidence of melanoma. The cause is unknown.
As at least two thirds of melanoma cases are caused by excessive sun exposure, the main preventive measure against skin cancer is, of course, reducing sun exposure. Recommendations on exposure to sunlight and ultraviolet rays:
Sunbathe
Do not spend so much time in the sun as to get sunburn
Do not tan
Use sunscreen at least factor 30, ideally factor 50. Reinforce the application every two hours
The use of sunscreen does not make it unnecessary to avoid prolonged sun exposure
Do not skimp on sunscreen. Most people make the pack last longer, not using the amount of sunscreen necessary for a proper protection of the skin
Wear sunglasses with UV protection
Avoid sun exposure during the period from 10h to 16h
Reduce the frequency with which you soak up the sun
Use hat when you stay too long in the sun
When working outdoors, wear light clothing but covering legs and arms
Melanoma can arise in any area of the body, but it usually appears in areas where there was intense sun exposure, such as back, arms, legs and face. Melanoma can also occur in areas with little sun exposure as soles, palms and under the nails. As melanocytes also exist in other areas of the body, melanoma less frequently arises in the eye, intestines and genital tract, for example.
Melanoma symptoms
The first symptom of melanoma is usually the appearance of a new dark spot on skin, or change in the old mole (nevus).
The American Society of Dermatology has developed a guide called ABCDE to advise doctors who are not dermatologists and patients to identify suspicious lesions. The guide says that melanomas have the following characteristics:
A - Asymmetry: common moles usually have the symmetrical shapes, usually round or oval. Melanoma is typically asymmetrical.
B - Borders: melanomas have irregular edges and blend with normal skin. The spots often have regular and well defined edges.
C - Color: melanomas usually have color variations within the same lesion, showing some areas with different color or greater intensity.
D - Diameter: the spots don't usually grow beyond 6 mm (0.6 inch) in diameter. Melanomas can start small, but lesions with more than 6 mm are characteristic of this type of skin cancer.
E - Evolution: moles that change shape, color or size over time are always considered to be passive lesions of skin cancer. If a mole begins to bleed, ulcerate or itch, also should be considered suspicious.
It is noteworthy that most of the spots (nevus) do not undergo conversion to melanomas, as well as most melanomas do not arise from these lesions. Melanoma is usually an injury initially flat. When it begins to turn into an elevated lesion on the skin it is a sign that is also growing in depth. The depth reached and the thickness of the lesion are the parameters that define the likelihood of metastasis and invasion of deeper tissues.
Diagnosis begins on clinical examination of suspect lesions. Experienced physicians can diagnose some cases only with the physical examination. However, the definitive diagnosis is made only with biopsy.
Since the biopsy confirms the presence of melanoma, the next step is to identify whether the lesion has spread throughout the body. To this end, it may be necessary to examine lymph node by biopsy around the lesion for signs of metastases. The deeper melanoma is, the greater is the risk of disseminated disease.
The processing depends on the degree of development of skin cancer, but in all cases the surgical removal of the entire lesion is indicated. In case of melanoma very early surgical removal is sufficient to cure. If the injury is already more advanced, chemotherapy and radiotherapy may be necessary.
Some patients may be treated with immunotherapy, which consists of administering drugs that enhance our immune system, causing the same to help fight the tumor cells. An example of a drug used in immunotherapy is Interleukin-2. This treatment has frequent side effects and not all patients can tolerate them.
