skin cancer
We can divide the skin cancer into 2 main categories: non-melanomas and melanomas.
Non-melanomas: carcinomas
The term “carcinoma” designates malignant tumors of epithelial origin (the epithelium is the constitutive histological structure of the skin and certain mucous membranes).
Carcinoma is the type of most commonly diagnosed cancer in Caucasians. It is relatively little talked about because it rarely results in death. In addition, it is difficult to identify cases.
Le basal cell carcinoma and squamous cell carcinoma or epidermoid are the 2 most common forms of non-melanoma. They usually occur in people over the age of 50.
Carcinoma basal cell alone constitutes approximately 90% of skin cancers. It forms in the deepest layer of the epidermis.
In Caucasians, basal cell carcinoma is not only the most common skin cancer, but the most common of all cancers, representing 15 to 20% of all cancers in France. The malignancy of basal cell carcinoma is essentially local (it almost never leads to metastases, secondary tumors that form far from the original tumor, after cancer cells have dissociated from it), which makes it very rarely makes it fatal, however its diagnosis too late, especially in perioriform areas (eyes, nose, mouth, etc.) can be mutilating, causing large losses of skin substance.
Carcinoma spinocellulaire ou epidermoid is a carcinoma developed at the expense of the epidermis, reproducing the appearance of keratinized cells. In France, epidermoid carcinomas come second among skin cancers and they represent around 20% of carcinomas. Squamous cell carcinomas can metastasize but this is quite rare and only 1% of patients with squamous cell carcinoma die from their cancer.
There are other types of carcinoma (adnexal, metatypical …) but they are quite exceptional
Melanoma
We give the name of melanoma to malignant tumors which form in melanocytes, the cells that produce melanin (a pigment) found especially in the skin and eyes. They usually manifest as a blackish stain.
With 5 new cases estimated in Canada in 300, melanoma represents the 7e cancer most frequently diagnosed in the country11.
The melanoma can occur at any age. They are among the cancers which can progress rapidly and generate metastases. They are responsible for 75% of death caused by skin cancer. Fortunately, if they are discovered early, they can be treated successfully.
Notes. In the past, it was believed that there could be benign melanomas (well-defined tumors that are unlikely to invade the body) and malignant melanomas. We now know that all melanomas are malignant.
Causes
Exposure to ultraviolet rays du sun is the main cause of skin cancer.
Artificial sources of ultraviolet radiation (solar lamps in tanning salons) are also involved. The parts of the body commonly exposed to the sun are the most at risk (face, neck, hands, arms). However, skin cancer can form anywhere.
To a lesser extent, prolonged skin contact with chemical products, especially at work, can increase your risk of developing skin cancer.
Sunburn and frequent exposure: be careful! Exposure to ultraviolet rays has cumulative effects, that is, they add up or combine over time. Damage to the skin begins at a young age and, although it is not visible, increases throughout life. The carcinomas (non-melanomas) are mainly caused by frequent and continuous exposure to the sun. The melanoma, for their part, are mainly caused by intense and short exposure, especially those that cause sunburn. |
Numbers:
– In countries where the majority of the population is White skin, skin cancer cases are at risk of double between the year 2000 and the year 2015, according to a United Nations (UN) report1.
– In Canada, it is the fastest growing type of cancer, increasing by 1,6% each year.
– It is estimated that 50% of people from over 65 will have at least one skin cancer before the end of their life.
– Skin cancer is the most common form of secondary cancer : by this we mean that a person having or having had cancer is more likely to have another, generally skin cancer.
Diagnostic
It is first of all a physical examination which allows the doctor to know if the lesion may or may not be cancerous.
Dermoscopie : this is an examination with a kind of magnifying glass called a dermoscope, which allows you to see the structure of skin lesions and to refine their diagnosis.
biopsy. If the doctor suspects cancer, he takes a sample of skin from the site of the suspicious manifestation for the purpose of submitting it for laboratory analysis. This will allow him to know if the tissue is indeed cancerous and it will give him an idea of the state of progression of the disease.
Other tests. If the biopsy shows the subject has cancer, the doctor will order further tests to further assess the stage of disease progression. Tests can tell if the cancer is still localized or if it has started to spread outside skin tissue.