A carcinoma (from the Greek karkinôma, cancer) or epithelioma is cancer developed from epithelial tissue (skin, mucous membrane). Depending on the type of epithelium, there are:
– squamous cell carcinoma or squamous cell carcinoma developed at the expense of a squamous epithelium;
– adenocarcinomas developed at the expense of a glandular epithelium;
– anaplastic, undifferentiated, embryonic carcinomas, etc.
The two main types of skin cancer are carcinomas (96% of cases) and melanomas (4% of cases).
Basal cell carcinoma is the most common but least aggressive skin cancer. The disease develops from the basal cells of the epidermis. About 75% of skin cancers are basal cell carcinomas. Basal cell carcinoma develops only locally.
Excessive sun exposure is the leading cause of carcinoma, along with other risk factors such as clear skin or smoking. They are most often located on the most exposed parts and therefore the most exposed to UV: face, neck, shoulders, forearms or hands.
I – What Is a Carcinoma?
Carcinomas develop from cells of the epidermis, the keratinocytes. Less serious than melanomas, they are the most common skin cancers. There are three distinct groups of carcinomas: basal cell carcinoma, squamous cell carcinoma, and adnexal carcinoma.
*** Basal Cell Carcinomas
With 40,000 to 50,000 new cases per year in France, basal cell carcinomas are by far the most common but also the most benign carcinomas. Unlike other types of skin cancer, they never give metastases.
Basal cell carcinoma is named after cells in the basal layer, the deepest layer of the epidermis from which it develops. This cancer of the skin is due to excessive, brutal and repeated exposure to the sun, which caused sunburn, especially during childhood. Diagnosed around 50 years, it is manifested by a characteristic lesion of the skin in the form of a pearl of a few millimeters. The firm, painless and translucent, it is usually covered with small vessels that give it its red color.
Among the basal cell carcinomas, superficial basal cell carcinomas with good prognosis and nodular basocellular carcinomas of intermediate-risk are distinguished. In the absence of management, they can develop in-depth, so-called invasive basal cell carcinomas.
*** Squamous Cell Carcinomas
About 4 times less common, squamous cell carcinoma or squamous cell carcinoma develops from the more superficial layers of the epidermis, where the cells seem to be joined together by kinds of spines. They are diagnosed later, around age 60-65, and slightly affect men more than women. Their dangerousness is due to their ability to cause metastases in the lymph nodes or organs at a distance (especially the lung); a risk evaluated between 2 and 5% when squamous cell carcinoma affects the skin, but that rises to 20% when it affects a mucous membrane (lips, genitals).
If UV exposure is the main cause of squamous cell carcinoma, it must be chronic and prolonged, especially through outdoor activities. Some professions are particularly at risk, such as farmers, sports instructors, sailors…
Unlike basal cell carcinoma, which appears on healthy skin, precancerous lesions, actinic keratoses, may precede the development of squamous cell carcinoma. These lesions are in the form of red or brown crusts, more or less thick. If they can regress spontaneously, it is preferable to treat them by the application of liquid nitrogen (if the lesions are few) or by other means (local chemotherapy or dynamic phototherapy if the lesions are numerous) to avoid their transformation. squamous cell carcinoma.
Learn more about squamous cell carcinoma in this video.
*** Adnexal Carcinomas
Far rarer, adnexal carcinomas develop at the expense of the appendages of the skin, such as the sweat glands, the hairs or the sebaceous glands.
II – Types of Carcinoma Cancers
1 – Chromophobic Cell Carcinoma:
Chromophobic renal carcinoma or chromophobe carcinoma is characterized by hypodiploidy.
2 – Clear Cell Carcinoma:
Clear cell carcinomas form a tumor phenotypic group characterized by large, clear cells with abundant cytoplasm and glycogen.
3 – Clear Cell Carcinoma of the Kidney:
Clear cell carcinoma of the kidney is a type of renal cell carcinoma of the kidney. It is characterized by abnormalities of the chromosomal region 3p and the VHL gene of von Hippel-Lindau disease.
4 – Merkel Cell Carcinoma:
Merkel cell carcinoma is a cancer of the skin. It is classified as rare as neuroendocrine skin tumors.
5 – Adenoid Cystic Carcinoma:
Cystic adenoid carcinoma, or cylindroma, is a cancer of the adenocarcinoma family, most often developed at the expense of the salivary glands, but also of the trachea or the lacrimal duct.
6 – Basal Cell Carcinoma:
Basal cell carcinoma (BCC) is a skin cancer that is highly amenable to treatment.
7 – Canal Carcinoma:
The ductal carcinomas are a class of solid tumors of the International Classification of Oncological Diseases. They are developed at the expense of the excretory ducts of an exocrine gland: breast, pancreas, prostate, lacrimal glands…
8 – In Situ Ductal Carcinoma:
In situ ductal carcinoma (DCIS) is an in situ carcinoma-type breast cancer affecting breast milk duct cells. It is a precursor to invasive breast cancer.
9 – Carcinoma of the Nasopharynx:
Nasopharyngeal carcinoma is cancer developing from the epithelial cells of the nasopharynx. It is one of the types of carcinoma cancers of the upper aerodigestive tract. It is the most common epithelial cancer in adults.
10 – Carcinoma of the Chimney Sweep:
The Chimney Sweep Cancer, formerly known as soot wart, is a squamous cell carcinoma of the scrotal skin. The first known example of occupational cancer, it was first identified by Percivall Pott in 1775.
11 – Embryonic Carcinoma:
Embryonic carcinoma is a type of germ cell tumor.
12 – Squamous Cell Carcinoma:
Squamous cell carcinoma or squamous cell carcinoma is a carcinoma that develops at the expense of squamous epithelium and can reach a squamous or glandular epithelium. This type of cancer can be found in several organs and is conventionally opposed to adenocarcinoma which develops at the expense of glandular epithelium.
13 – Hepatocellular Carcinoma (HCC):
Hepatocellular carcinoma (HCC), or hepatocarcinoma, is a primary cancer of the liver. It is the most common type of primary liver cancer in adults and the most common cause of death in people with cirrhosis.
14 – Carcinoma in Situ:
In situ carcinoma or cancer in situ (CIS) is a carcinoma that is limited to the epithelium. This early stage of cancer is characterized by a proliferation of cancerous epithelial cells that do not cross the basement membrane. The underlying connective tissue is therefore unaffected and metastases are therefore impossible. Typically, carcinoma in situ evolves into invasive carcinoma, that is, it can cross the basement membrane of the epithelium. However, in principle, it can remain confined for several years, or even regress spontaneously.
15 – Lobular Carcinoma in Situ:
In situ lobular carcinoma or CLIS is an area of abnormal growth of epithelial cells of a breast lobule. It may resolve or remain stable, or sometimes progress to ductal or lobular breast cancer, but is not considered to be cancer or even a pre-cancerous condition. It is a risk factor for invasive breast cancer, although it is grouped into breast carcinoma in situ. It is an indicator of early detection of breast cancer. It represents 10 to 15% of breast carcinomas in situ or less than 4% of all types of carcinoma cancers of the breast.
16 – Invasive Lobular Carcinoma of the Breast:
Invasive lobular carcinoma of the breast is a particular form of breast cancer.
The management is identical to other forms of breast cancer.
This particular form is characterized by lower chemosensitivity, a higher incidence of bilateral cancer at the time of diagnosis, and the possibility of metastatic progression in the form of peritoneal carcinomatosis.
17 – Breast Carcinoma:
Breast carcinoma can refer to different forms of carcinoma affecting the breast:
* malignant forms, grouped under the name of breast cancer, including invasive lobular carcinoma of the breast;
* pre-cancerous forms, such as ductal carcinoma in situ;
* Bégnine forms such as lobular carcinoma in situ.
18 – Neuroendocrine Carcinoma With Giant Lung Cells:
This type of carcinoma cancer, named Neuroendocrine carcinoma with large lung cells, represents 3% of lung cancers. Most of these tumors develop at the periphery of the lung parenchyma and share the symptoms and clinical presentation of other non-small cell carcinomas.
19 – Giant Cell Lung Carcinoma:
Giant cell lung carcinoma is a subtype of large cell lung carcinoma (or anaplastic large cell carcinoma).
20 – Large Cell Lung Carcinoma:
Large cell lung carcinoma (or large cell anaplastic carcinoma) is a type of lung carcinoma. It is a heterogeneous entity with several subtypes:
* Large cell lung carcinoma (NOS)
* Neuroendocrine carcinoma with giant lung cells
* Giant cell lung carcinoma
* Clear cell lung carcinoma
* Rhabdoid-like lung carcinoma
21 – Squamous Cell Carcinoma:
Squamous cell carcinoma (or skin squamous cell carcinoma) is a skin cancer developed from keratinocytes. More superficial than basal cell carcinoma, it has the particularity of being able to metastasize, hence its malignant character.
Squamous cell carcinoma is most often found in precancerous lesions: actinic keratosis (or precarcinomatous keratosis), Bowen’s disease, bowenoid papulosis.
22 – Urothelial Carcinoma:
Urothelial carcinoma (or transitional cell carcinoma) is the most common morphological form of cancer of the excretory pathways (calices, pelvis, ureters, bladder, urethra).
It accounts for 90% of bladder cancers.
23 – Low-Grade Non-Infiltrating Papillary Urothelial Carcinoma:
Low-grade non-infiltrating papillary carcinoma (WHO 1973 G1 and G2) is a type of papillary urothelial lesion.
24 – Non-Infiltrating Papillary Urothelial Carcinoma of High Grade:
High-grade non-infiltrating papillary urothelial carcinoma (WHO 1973 G2b and G3) is a type of papillary urothelial lesion.
III – Risk Factors for Carcinoma
Although the main cause of carcinoma is excessive exposure to the sun, not everyone is at the same risk: people with light skin, who have difficulty tanning and who are easily sunburned, should be particularly vigilant when exposing themselves.
Tobacco promotes the development of squamous cell carcinoma of the lip, but its role in the appearance of other types of carcinoma is not known.
The viral track is also pointed out: human papillomavirus (HPV) could indeed be involved in cutaneous squamous cell carcinoma, but especially mucous membranes.
Finally, there are other risk factors for carcinoma, such as radiotherapy, certain chronic skin diseases such as leg ulcers or burn scars, or a failure of the immunity induced by a disease or the taking of immunosuppressants.
IV – How to Avoid the Development of Different Types of Carcinoma Cancers?
The prevention of carcinomas is based essentially on reasonable exposure to the sun and effective protection of the skin. It is particularly important to educate children and adolescents about the risk of cutaneous carcinomas and the importance of protective measures against this cancer.
Be careful, taking beta-carotene in the form of food supplements or even UV sessions in tanning booths do not in any way constitute a means of prevention against sunburn and therefore cutaneous carcinomas!
V – The Diagnosis of Carcinoma
It is recommended to monitor your skin closely and report to a dermatologist any suspicious lesion that has evolved (change in size, bleeding, ulceration …). The specialist will perform a thorough clinical examination as well as a biopsy of the lesion for analysis. Carried out in an anatomopathology laboratory, this one aims to specify the nature of the lesion, to invalidate or to confirm the diagnosis of carcinoma and, if necessary, to specify its origin as well as the characteristics.
In case of basal cell carcinoma, this examination is used for both diagnosis and treatment, removal (excision) of the lesion and a little skin around the main treatment.
If the lesion turns out to be squamous cell carcinoma, an extension check for lymph node involvement is required. A thorough clinical examination is usually sufficient, but an ultrasound may be useful. If there is suspicion of metastases, further examinations may be requested.
VI – The Treatment of Carcinoma
The treatment of carcinoma is based on surgery and removal of the tumor and a margin of safety, to reduce the risk of recurrence; this will be greater in the case of squamous cell carcinoma. As far as possible, the dermatologist performs a simple suture, a gesture that limits the aesthetic prejudice and allows rapid healing. But sometimes it must leave the scar alone; he then uses healing fatty dressings, which extend the healing time to 2 months. For extensive lesions, it can also proceed to the technique called skin flaps or skin grafting, whose healing times are respectively 3 weeks and 2 months. Regular follow-up, every 6 months the first year, then every year, is then essential to ensure the absence of recurrence or another lesion.
Superficial basal cell carcinomas or some squamous cell carcinomas can be treated with local chemotherapy with imiquimod or 5-fluorouracil. It is also possible to use a combination of photosensitizing ointment and light irradiation to destroy the tumor (dynamic phototherapy).
For larger tumors that cannot be treated by surgery, however, radiotherapy is a possible alternative, although less effective, both therapeutically and aesthetically.
Squamous cell Carcinoma : Molecular Therapeutic Targets
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