A type of cancer that starts in the epithelial tissue is known as carcinoma. This is the most common type of cancer to be diagnosed. It can affect the epithelial tissues of the skin or any other organ such as the liver or kidney. Depending on each case, cancer can either spread to other parts or stay confined to its place of origin. This article will elucidate the types, symptoms, causes, risk factors, diagnosis, and treatment options for carcinoma.

Types of carcinoma
Carcinoma can be classified into subtypes depending on the type of cell it originates from. In some cases, there can be various types of carcinoma developing in the same organ. Therefore, it is often categorized by the subtype instead of an organ. The common subtypes of carcinoma include:

Basal cell carcinoma: This subtype of carcinoma is only found occurring in the skin. The majority of skin cancers that are not diagnosed as melanoma are basal cell carcinoma. This subtype of carcinoma does not grow fast and, in most cases, does not spread. It is commonly caused by sun exposure.

Squamous cell carcinoma: This subtype of carcinoma is often associated with skin cancer. However, it is commonly found to be affecting other body parts. Squamous cell carcinoma can impact common areas in the body, such as:

• Skin: When squamous cell carcinoma affects the skin, it usually does not spread. However, the occurrence of metastasis is more common than basal cell carcinoma.
• Lungs: Around 25 percent of lung cancer patients have squamous cell carcinoma, as per the American Cancer Society.
• Esophagus: Usually, cancers that are found in the upper esophagus are found to be squamous cell carcinoma.
• Neck and head: As many as 90 percent of mouth, throat, and nose cancer cases are squamous cell carcinoma.

Kidney cancer or renal cell carcinoma: Almost 90 percent of all kidney tumors are renal cell carcinoma. Renal cell carcinomas are known to grow as a single mass in the kidneys.

Transitional cell carcinoma: At the center of the kidney and the ureter, transitional cells can be found. The carcinoma of transitional cells accounts for around 10 percent of kidney cancer cases.

Adenocarcinomas: There are epithelial cells that are responsible for secreting substances such as mucus. These are known as glandular cells and are commonly found at the linings of the organs. The cancer of these cells is known as adenocarcinomas. The common adenocarcinomas include:

• Colorectal cancer
• Pancreatic cancer
• Prostate cancer
• Breast cancer
• Lung cancer

After the diagnosis of the carcinomas, depending on how and if it spreads to other parts of the body, it is further categorized into one of the three types. These are:

• Carcinoma in situ: This refers to the category in which the cancer is confined to the epithelial cells from which it originated. Here, cancer does not spread to other parts.
• Invasive carcinoma: This refers to the category in which the cancer has reached the nearby tissue. The spread is still local.
• Metastatic carcinoma: This subtype refers to cancer that spreads and affects parts of the body that are far from the epithelium.

Symptoms of carcinoma
Carcinoma and skin cancers usually develop at places where they are visible to the eyes. Therefore, there is a high chance of diagnosing the disease at an early stage. Conducting skin examinations regularly will help one keep a check on any new or abnormal growths on the skin. This also allows a person to keep a close watch on any changes in the existing moles, which can prove to be critical in diagnosing the condition. Any unusual growth that could be a matter of concern should be immediately brought to the notice of a dermatologist or physician who can identify the symptoms of skin cancer and help with the diagnosis.

Among the first signs of carcinoma is an abnormal sore or growth on the skin that stays for a long duration. In its initial stages, skin cancer will appear in the form of a rash or a patch on the skin surface. These unusual growths can also ooze out blood sometimes. With the progression of the condition, the unusual growths on the skin start changing in shape and size, and they may start reaching the skin’s deeper layers. Without the consultation of a dermatologist, it might not be possible to know the type of skin cancer one might have. Therefore, as soon as one notices any uncommon activity on the surface of the skin, they must immediately consult a doctor.

Symptoms according to various types of carcinomas include:

Basal cell carcinoma: The initial symptoms of this type of carcinoma are a patch of skin that appears to be pale or a translucent bump, which contains a waxy substance. Blood vessels may appear at the center of the mass. In case the carcinoma has developed on the chest, the mass will resemble a brown scar or a lesion, which is flesh-colored. With the progression of the disease, the mass may start to bleed or ooze if injured. Some areas of the mass can also become crusty.

Squamous cell carcinoma: The core symptom of this type of carcinoma is the development of a lump on the skin. However, unlike the lumps of basal cell carcinoma, the initial lumps of this type of carcinoma usually appear to be rough on the skin’s surface. If there is no development of a nodule, with the progression of the disease, the lump can become a scaly, red patch. These skin lesions do not go away. In fact, as the disease advances, the patches also keep developing slowly. Commonly, this type of cancer affects the arms, head, or neck. However, they may also affect other parts of the body such as in skin sores, scars, or the genital area.

Merkel cell carcinoma: The symptom of this type of carcinoma includes raised moles that are flesh-colored, and have a rapid growth rate. They usually appear in the areas that are more commonly exposed to the skin such as the scalp, neck, or face.

Causes and risk factors
The main cause associated with carcinoma is exposing the skin to the ultraviolet rays of the sun. This is not only the primary cause of carcinoma, but it can also lead to several other types of cancers. Vulnerability to the harmful effects of the sun’s UV rays also depends from person to person. While some people might be at a high risk of developing cancer due to exposure to the sun’s UV rays, others might be at a lower risk.

If a person is frequently exposing their body to UV rays from tanning beds or drying lamps, they can be at an additional risk of developing cancer due to exposure to UV rays.

Exposure to UV rays can cause damage to the DNA in skin cells. This results in gene mutation at the time of cell division and eventually leads to skin cancer.

There are a number of factors that increase the chances of a person developing carcinoma. These include any history of the disease and if the person is undergoing any radiation treatment to cure any form of cancer. If there has been a family history of cancer, that can also contribute to its development.

Some other risk factors include:

• Having a breakout of a large number of moles or freckles
• Having fair skin
• Having systemic lupus erythematosus or any other autoimmune diseases
• Having Gorlin syndrome, xeroderma pigmentosum, or any other inherited conditions
• Having a weak immune system, which could be due to HIV, an organ transplant, or consumption of immunosuppressant medications
• Consuming medications that lead to photosensitivity of the skin
• Contracting the human papillomavirus (HPV) infection, especially in people who have a weak immune system.

Another risk factor specifically associated with squamous cell carcinoma is actinic keratosis. Actinic keratosis is a rough, scaly growth that can lead to precancerous activities in the skin cells. Actinic keratosis is the most common form of skin lesions that are precancerous. If left untreated, it can progress and go on to become skin cancer.

Exposure to harmful UV rays is the most common cause of squamous cell carcinoma. Certain types of skin damages could also contribute to the risk of squamous cell carcinoma. These include:

• Skin burns
• Damage from chemicals
• X-ray radiation exposure

Although not as common as exposure to UV rays, undergoing X-ray radiation during childhood can also lead to basal cell carcinoma.

Diagnosis of carcinoma
A physical examination will be carried out by the doctor to diagnose any type of skin cancer. The skin lesion will be checked for its shape, texture, size, and other attributes.

A photo of the lesion can also be taken for a review by a specialist or to check its growth for future references. Additional symptoms of skin cancer will also be checked on other parts of the body.

The medical history of the patient will also be taken into consideration while examining the lesion.

If the lesion is suspected to be cancerous, the doctor can order a biopsy.

Treatment options for carcinoma
Usually, the course of treatment for both basal cell carcinoma and squamous cell carcinoma is similar. However, people with squamous cell carcinoma are recommended to be put under close monitoring for any indication towards metastasis.

The treatment plan prescribed by the doctor will largely depend on certain factors such as:

• Size of the carcinoma
• Type of carcinoma
• Stage of carcinoma
• Part of the body it affects

Some other factors, such as any side effects and the preferences of the patient, will also be taken into consideration by the doctor while prescribing treatment.

A team of doctors will be working together to get the best results out of the treatment. The team will include:

• A dermatologist
• A surgical expert
• A medical expert
• A radiological cancer specialist

The various treatment plans that can be prescribed include:

Electrodesiccation and curettage: The standard procedure is usually used to remove small lesions. An instrument called curette is used to scrape the carcinoma, which is followed by burning of the site using an electric needle. In some cases, more than just one round of scraping and burning of the site can be required to eliminate cancer cells completely.

Surgical excision: A surgical procedure known as “Mohs surgery” can be used to remove lesions. This surgery is usually more effective on lesions that are large in size. During the surgery, after removing every layer, the doctor also looks for any presence of cancerous cells.

This surgery is commonly done in cases where minimal skin removal is required. For example, removing lesions that develop around the eye area. Also, the surgery can be used to remove lesions that have a high chance of recurring.

Cryosurgery: This procedure is usually used to remove small tumors. In this procedure, liquid nitrogen is applied to kill cancerous cells by freezing them. As a result of this procedure, the lesion blisters and falls from the skin after a few weeks.

Topical chemotherapy: This is a treatment procedure in which medications or chemicals are used on the skin directly to kill the cancer cells. The drugs that help in killing the cancer cells can be applied once or twice every day for many weeks.

Since the treatment remains restricted to only one part of the body and does not reach any other part, it has no side effects. This is unlike chemotherapy, which is used as a treatment for several cancer types.

Radiation therapy: With this treatment, lesions that are large or tough to remove are targeted with radiation.

Laser therapy: This treatment consists of various kinds of lasers that are used to kill cancer cells. With the help of some lasers, the top layer of the skin is vaporized. As a result, any lesions present in the area are also destroyed.