Carcinomas are cancers or malignancies that begin in the epithelial cells, which are the cells that make up the skin, and the tissues that line various internal organs and structures. Some of the most common carcinomas affect the breast, lung, prostate, and colon.

Sebastian Kaulitzki | Shutterstock

How do carcinomas develop?

The body is made up of trillions of living cells that grow, divide and die in a highly regulated way that is controlled by DNA. In a fetus, baby or a child, cells rapidly divide to allow the child to grow, whereas cells in adults will only divide to replace worn-out or dying cells, or to repair injuries.

Cancer occurs when certain mutations take place in our genes, such as DNA. Genetic mutations can negatively affect the way in which cells properly grow and divide. These mutations can arise as a result of exposure to various different sources, some of which include:

• Radiation (e.g., sunlight)
• Viruses
• Smoking/Tobacco

Genetic mutations often affect the ability of cells to reproduce in a controlled manner. As a result, new and abnormal cells are produced. These abnormal cells can then invade other tissues, a process referred to as malignancy, that often causes serious damage to surrounding tissues.

Types of Carcinomas

Carcinomas are classified according to their origin within the body. Common carcinomas include:

Basal Cell Carcinoma

As the most common type of skin cancer, basal cell carcinoma develops from the bottom layer of the skin, which is otherwise referred to as the basal layer. This type of cancer typically grows at a slow rate, thereby limiting its ability to spread to other parts of the body. Some of the typical skin symptoms associated with a basal cell carcinoma include:

• Open sores
• Red patches
• Pink growths
• Shiny bumps or scars

Squamous Cell Carcinoma

As the second most common type of skin cancer, squamous cell carcinoma is a slow growing cancer that does not usually spread to other organs in the body. The most common areas of the body affected by squamous cell carcinoma include the skin, gastrointestinal tract and respiratory tract.

Renal Cell Carcinoma

As the most common type of kidney cancer, renal cell carcinoma begins in the tubules of the kidneys. These cancerous cells can continue to grow, leading to its ability to impair normal kidney function.

Invasive Ductal Carcinoma

The cells that grow and reside within the milk duct lining of the breast are affected by invasive ductal carcinoma. As this cancer continues to grow, these cancerous cells can break through the wall of the milk ducts and invade other parts of the body.

Aside from their cellular origin, carcinomas are also commonly classified by the specific organs they affect. Some examples of these carcinoma classifications include:

• Adrenocortical carcinoma, which affects the adrenal glands,
• Thyroid carcinoma, which affects the thyroid gland,
• Nasopharyngeal carcinoma, which affects the nose and pharynx.

Carcinoma-in-situ

Carcinoma-in-situ (CIS) is a term used to describe cancer cells that have not spread beyond their original location. In fact, the term “in situ” translates into “in its original place.” Some common in-situ carcinomas include:

Ductal Carcinoma in-situ

Ductal carcinoma in-situ is the most common type of breast cancer. While this may be true, these cancer cells remain confined to the milk duct lining within the breast, thereby preventing the spread of this cancer from escaping the duct walls to surrounding breast tissue. As a result, patients with ductal carcinoma in-situ typically have good prognosis rates upon diagnosis.

Carcinoma in-situ of the Urinary Bladder

Carcinoma in-situ of the urinary bladder is commonly found in male smokers between the age of 60-70 years old. There is a 90% recurrence rate of this type of cancer.

Cervical Carcinoma in-situ

The diagnosis of cervical carcinoma in-situ typically follows the identification of pre-cancerous cells present on the surface layer of the cervix.

Bowen Disease

Bowen Disease, which is also known as squamous cell carcinoma in situ, typically arises as a result of sun exposure. Therefore, the most common areas of the skin affected by Bowen Disease will include the face, ears, and neck.

Further Reading

• All Carcinoma Content
• Carcinoma Staging and Grading
• Types of Lung Carcinoma
• Acinic Cell Carcinoma

Written by

Benedette Cuffari

After completing her Bachelor of Science in Toxicology with two minors in Spanish and Chemistry in 2016, Benedette continued her studies to complete her Master of Science in Toxicology in May of 2018.During graduate school, Benedette investigated the dermatotoxicity of mechlorethamine and bendamustine, which are two nitrogen mustard alkylating agents that are currently used in anticancer therapy.