Aspects of melanoma prevention

The average annual increase in melanoma in the world is about 5% (in the USA - 4%, in Russia - 3.9%), which is regarded as one of the highest among all malignant tumors, except lung cancer. The negative aspects of the incidence of MC are the involvement of young people, the low detection of the disease in the early stages, the aggressiveness of the course and, as a consequence, a significant mortality rate. There is evidence that 5-year survival rates remain low, and unsatisfactory treatment results necessitate efforts to improve them. At the same time, early diagnosis of melanoma in the initial stages with adequate treatment allows 90% of patients to survive the 10-year mark without manifestation of the disease [2, 8]. This became possible, primarily due to widespread propaganda among the population of knowledge about this malignant tumor. A thorough examination of the entire skin of patients by doctors also plays an important role. However, according to researchers, despite the obvious localization of the tumor, 40-60% of patients seek help at stages when the disease has become systemic [1, 3]. One of the reasons is that most people do not know what a normal nevus should look like and what to look for. According to numerous studies, people are usually more worried about a mole or other skin growth that is itchy or bleeding than about a mole that has increased in size, changed shape or color. At the same time, according to histological studies, no more than 35% of melanomas develop at the site of previous nevi, the rest - de novo - on unchanged skin [7].

The widespread increase in the incidence of MC raises the challenge of a more in-depth study of the epidemiology, pathogenesis, and especially the etiology of this disease. The main risk factors for this disease include: genetic predisposition and environmental influences. Genetics determines the skin phototype and the characteristics of its reaction to solar radiation: persons with phototypes I and II are much more sensitive to solar radiation. Particular attention should be paid to persons with numerous nevi, especially dysplastic ones, and large birthmarks. Individuals with these genetic manifestations should be regularly examined by family members, family physicians, and dermatologists.

You should pay attention to the following signs of pigment formations:

• symmetry;
• uniformity of pigmentation;
• outline and relief;
• diameter;
• Is there an increase in size?

Of the environmental factors, solar radiation ranks first. In this case, the duration of exposure to the sun (total, that is, throughout life), the area of skin that is exposed to irradiation, the power of irradiation and age are important: a young developing organism is more sensitive to the effects of sunlight.

It has long been known about the negative effect of solar radiation on the development of tumors such as melanoma, squamous cell carcinoma, and skin basal cell carcinoma. Holiday tanning is especially harmful for residents of central Russia, when the body receives a large dose of ultraviolet radiation in a short period of time. Also, great importance is attached to the total dose of solar radiation received in the first five years of life and the presence of a history of sunburn, especially often repeated in childhood [5]. It is assumed that for residents of the southern regions, constant, in small doses, exposure to ultraviolet radiation has some protective effect and reduces the risk of developing skin melanoma.

Pigmentation, or sun tanning, can be immediate or delayed. Instant darkening of the skin occurs a few minutes after sun exposure and is associated with photooxidation of already synthesized melanin, its rapid redistribution into the dendrites of melanocytes and subsequently into epidermal cells. Delayed pigmentation occurs after 48-72 hours and is associated with activation of melanin synthesis in melanosomes, an increase in the number of melanocytes and activation of synthetic processes in previously inactive pigment cells. This process is a reflection of the protective properties of the skin in response to ultraviolet radiation [6]. Delayed pigmentation can also be explained by the formation of secondary post-inflammatory pigmentation as a result of simple dermatitis or burns.

In dermatological terms, sunburn is a dermatitis that manifests as erythema and swelling (grade 1) or erythema and blistering (grade 2). More serious manifestations (3rd degree burns, etc.) are extremely rare - mainly in infants and are accompanied by heat shock. It is believed that the development of a 1st degree sunburn is possible if a person has received 4 minimal erythematous doses in 24 hours, 2nd degree - 8. This is possible in the case of 10-35 minutes of exposure to the sun without the use of photoprotective agents during the daytime. latitude of New York (40o). For the latitude of Cairo (25°), the indicated time is halved [4].

In case of chronic exposure to ultraviolet radiation, the following symptoms are observed: vascular changes, pigmentation disorders, development of skin tumors, changes in turgor, elasticity, and skin pattern. In this case, vascular changes are represented by persistent diffuse erythema; the formation of telangiectasia, ecchymosis in areas most susceptible to irradiation (face, hands, parietal and occipital regions, back of the neck, etc.). Pigmentation disorders can manifest as ephelides (freckles), solar lentigo, dyschromia, chronic guttate idiopathic hypomelanosis and Siwatt's poikiloderma [4, 10]. These clinical manifestations, along with signs of photoaging, are called “sun damaged skin.” Also, prolonged excessive ultraviolet radiation causes the development of various precancerous diseases and conditions, as well as basal cell carcinoma, squamous cell carcinoma, and melanoma. Among precancerous diseases, actinic keratosis is distinguished (more often found in individuals of phototypes I and II). Skin cancer is a multi-etiological disease, but it is known that in open areas of the skin it occurs 200 times more often than in closed areas [4, 9]. Acute (than chronic) photodamage to the skin is more dangerous for the development of melanoma, especially sunburn in children under 10 years of age. Some researchers believe that A rays play a greater role in the development of melanoma than B rays [9]. Therefore, it is necessary to emphasize the importance of using products that protect against both UVA and UVA rays at the same time.

An important role in the pathogenesis of melanoma is played by the skin phototype, which determines the reaction of the skin to ultraviolet radiation (Table 1).

Table 1

It is known that representatives of phototypes I and II have an increased risk of developing melanoma. This group mainly includes white-skinned people with blond or red hair, blue eyes and numerous freckles. Natural or artificial insolation is strictly contraindicated for them. In this regard, they were recommended to optimize measures aimed at reducing the dose of ultraviolet radiation reaching the skin - photoprotection. These measures include reducing the time spent in the sun from 10 to 16 hours, and allowing short exposures only in the early morning and evening hours, and wearing clothing. It is known that ordinary summer clothing provides photoprotection similar to the use of sunscreen with SPF 7-8 [4, 9].

There are both exogenous and endogenous photoprotectors. Endogenous photoprotectors are substances for oral administration that have anti-inflammatory and antioxidant effects, which include reducing the amount of free radicals and accelerating the rate of regenerative processes. These substances include: tocopherol acetate (vitamin E), ascorbic acid, retinol, selenium, β-carotene, aspirin, indomethacin, antihistamines, antimalarials, systemic corticosteroids and other agents [9].

Exogenous photoprotectors are intended for direct application to the skin surface and are produced mainly in the form of an emulsion (cream), spray, or oil. There are sunscreens with primary protection from UVB and UVA. At the same time, UVB protection products were the first to be used. Thus, already at the beginning of the last century, a sunscreen with 2% salol (phenyl salicylate) was described. Currently, this group includes PABA (or PABA) and its derivatives, salicylates (including phenyl salicylate), cinnamates and other compounds. The group of products with preferential protection against UVA is represented by benzophenones (oxybenzone, dioxybenzone, benzophenone, etc.) and dibenzoylmethanes (avobenzone). Modern photoprotectors are divided into chemical (filters) and mineral (screens) based on their mechanism of action. The action of chemical filters is ensured by the absorption of certain types of energy, while screens reflect it, partially adsorbing it (especially B radiation). In this regard, the most widely used products are those containing chemical filters - para-aminobenzoic acid, salicylates, cinnamates, benzophenones, dibenzoylmethane (Parsol 1789), drometrizole trisiloxane (Mexoryl). Mineral photoprotectors include titanium dioxide, zinc oxide, red iron oxide and other agents.

The effect of any photoprotective agent is assessed by its activity in relation to protection from a certain type of rays. The degree of protection against UVB is determined by the sun protective factor (SPF). This indicator is the ratio of the minimum erythema dose that occurs when skin is irradiated with a photoprotector to the minimum erythema dose without a photoprotector. It is expressed as simple numbers and is calculated for each photoprotective product separately. To assess the degree of protection from UVA, several indicators are used, which are based on the severity of immediate and delayed skin pigmentation that occurs in response to the action of these rays on skin protected and unprotected by a photoprotector (IPD - immediate pigment darkening, PPD - persistent pigment darkening). A factor based on the degree of phototoxicity is also used [4]. It should be noted that the sun protection factor cannot reflect the degree of protection from UVA, since these rays are not erythmogenic.

Modern requirements for an “ideal” photoprotective agent include good tolerance, non-toxicity, effective protection against UVA and UVB simultaneously, a high sun protection factor, photostability, water resistance, and comfort in use. Such products include products containing Mexoryl, as they have a wide spectrum of protection from UVA and UVB, as well as high photostability and water resistance [9].

These products primarily include the Antgelios series products, developed by the French company La Roche-Posay. They have maximum protection against UVA rays (IPD 80/PPD 28), which is due to the synergistic action of Mexoryl XL and Mexoryl SX filters. At the same time, this series contains an extremely wide spectrum of action: UVB (SPF - from 20 to 60+) and short-wave and long-wave UVA rays with high photostable protection. All Antgelios products are also designed for any skin type (milk, cream, gel, spray) and any age (Table 2) and are based on La Roche Pose thermal water, containing the antioxidant selenium.

Range of sunscreens from the Anthelios series

Table 2.

Thus, there is no doubt that the active professional position of dermatocosmetologists in relation to congenital nevi (birthmarks) and skin dyschromia in general will eliminate situations where the diagnosis of melanoma is no longer in doubt by a specialist, and the prognosis for the patient’s life is most likely unfavorable. Only timely diagnosis of this most malignant tumor in humans, which is achieved by widespread propaganda among the population of knowledge about it, a thorough professional examination of the skin, primarily by dermatocosmetologists, prevention of exposure to risk factors for this disease, especially optimization of the popularization of adequate photoprotection among the population, will lead to a reduction in mortality from melanoma.

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