It seems that there is no cell type in the human body that lacks the potential, in the worst of circumstances, to develop cancer. Skin cells, always exposed to the harshness of the external environment, are no exception.
There are different types of skin cancer, caused by different cell types, such as carcinomas caused by basal cells of the skin. The most feared is melanoma.
In one respect, melanoma is the most dangerous skin cancer (it is the leading cause of death from skin diseases), but it is also the rarest.
The responsible cells are melanocytes. Melanocytes produce melanin, the pigment that colors our skin and hair. However, their function is not aesthetic but photoprotective: to prevent DNA mutations caused by ultraviolet radiation from sunlight.
Interestingly, melanocytes produce melanin, but do not store it; they send it to keratinocytes, the cells that form the epidermis in the skin, which perform the true protective function.
Therefore, the main stimulus for melanocyte activity is sunlight. It causes tanned skin, the appearance of freckles, and the risk of melanoma.
This explains why melanomas are common in areas of the skin exposed to sunlight. However, it is not an absolute rule. Internal areas, such as the nasal cavities or the throat, can also develop it.
Melanomas that appear in areas like the mouth or anus are called mucosal melanoma and are considered a subtype.
There is even ocular melanoma, which occurs in the eye, as this organ also possesses melanocytes.
Skin melanomas are classified into four main types:
- Superficial spreading melanoma. These make up 70% of melanomas. They arise as a benign freckle and often remain stable for a while before penetrating deeper into the body and becoming dangerous. This is the image we have of a classic melanoma.
- Nodular melanoma. Of all the types of melanoma, this is the last one you would want to have. It is the most aggressive, with an almost black tone, and can easily be mistaken for a normal mole.
- Lentigo maligna melanoma. It grows on the skin for a while before becoming invasive. It is common in older individuals who have lived exposed to the sun for many years.
- Acral lentiginous melanoma. It is the least common, characterized by appearing on the soles of the feet and hands, or under the toenails and fingernails.
Where is the fire?
But why such panic over a cancer that arises far from vital areas and in a manner that should facilitate its detection?
The first stage of melanoma meets these conditions. The cells grow at the level of the epidermis, without reaching the deeper blood vessels. At this stage, surgical removal of the area of skin where it is located is sufficient to cure the pathology.
The fear begins when they grow vertically, deepening. These tumors usually have a thickness of 1 mm or more and, by reaching the blood and/or lymphatic vessels, they can produce metastasis.
At the point when it reaches a transport pathway through the body, the benign melanoma (if it still was benign) becomes completely malignant melanoma.
That’s the problem. It’s a cancer with a high invasive capacity. There have been cases where doctors have detected a melanoma metastasis, only to discover that the person’s immune system has eliminated the primary, original tumor.
Result: melanoma accounts for 4% of all diagnosed cancers (not counting non-melanoma skin cancers) and 1.3% of all cancer deaths.
Detect and Eliminate
The main way to detect a melanoma is to monitor unusual moles. After visual examination, for which the doctor uses various magnification instruments, a biopsy is common.
The extraction, under local anesthesia, of the suspicious skin area is performed to confirm the diagnosis and assess the severity.
If detection is early, in most patients, surgical removal can be performed that does not require subsequent immunotherapy.
In high-risk melanomas, additional measures are taken. These additional measures include chemotherapy, personalized therapies against their melanoma, and immunotherapy (which aims to strengthen the patient’s immune system to fight cancer).
Blood tests for melanoma are also common. Their purpose is not to detect it but to assist in monitoring the disease and treatment, especially in aggressive forms.
The main prognostic factor for melanoma is the spread of cancer cells. Between 2012 and 2018, more than 99% of people diagnosed before metastasis was observed were still alive 5 years later. In people who had the presence of cancer in other organs such as the liver, that percentage dropped to 32%.
Other factors include age and the state of their immune system.
Genetics in Melanoma, Saved for Last
Now the classic question, is melanoma hereditary? With the classic answer, melanoma is not inherited, but the risk is. 10% of patients with melanoma report having a family member who has also suffered from the disease. You inherit the predisposition to develop a skin cancer such as melanoma.
5% of people who have developed a melanoma have subsequently suffered primary melanomas again, which is indicative of genetic causes (let’s assume these people have taken extra precautions with other risk factors).
In this cancer, the two main risk factors are exposure to ultraviolet radiation and genetics.
For example, one of the involved genes is MC1R. This gene not only slightly increases the risk of developing this type of cancer but is also the main responsible for the existence of redheads.
There are other genes that increase the risk, such as CDK4 and CDKN2A, which are risk factors in many other types of cancer. The CDKN2A gene is possibly the most studied within the familial forms of melanoma.
However, it is a very heterogeneous cancer. The total genetic risk is not so much due to a few heavily weighted genes but to the confluence of many genes with a low risk value. Because of this, making a genetic prediction of risk in melanoma is very complicated.
That does not prevent efforts to achieve it, such as the Advanced DNA kit from tellmeGen.
