Squamous cell carcinoma is a form of cancer that develops as a crusty lesion that tends to bleed. The tumor is often characterized by a lesion localized in the epidermis, the outer layer of the skin. The injury may take the form of a scaly or crusty bump (actinic keratosis) or a scaly erythematous plaque (Bowen’s disease). Over time, however, the cancer can penetrate deeply into the skin and spread into nearby or distant lymph nodes.

Squamous cell carcinoma is common among people aged 50 or over; it affects primarily individuals having fair or/and blond hair. In general, squamous cell carcinoma has a higher invasive power than that of basal cell carcinoma; metastasis is registered in about 20% of cases. However, diagnosed and treated early, squamous cell carcinoma has a cure rate of about 90%.

Besides the skin, squamous cell carcinoma can affect many other organs.

Your chance of surviving varies depending on the organ affected and the characteristic of the tumor.  Some of the organs that are subject to squamous cell carcinoma include:

• lips– squamous cell carcinoma of the lips;
• mouth(including floor of the mouth, the tongue and the soft palate) – squamous cell carcinoma of the mouth or intraoral squamous cell carcinoma;
• esophagus– squamous cell carcinoma of esophagus or esophageal squamous cell carcinoma (ESCC)
• bladder– squamous cell carcinoma of the bladder or bladder squamous cell carcinoma
• prostate– squamous cell carcinoma of the prostate or prostatic squamous cell carcinoma
• lungs– squamous cell carcinoma of the lung or pulmonary squamous cell carcinoma
• vagina– squamous cell carcinoma of the vulva or vulvar squamous cell carcinoma
• And cervix– squamous cell carcinoma of the cervix or cervical squamous cell carcinoma.

Types of Squamous Cell Carcinoma 

 Squamous cell carcinoma can take different forms, depending on the group of cells affected:

• Adenoid squamous cell carcinoma(also called Pseudoglandular squamous cell carcinoma) – an uncommon subtype of squamous cell carcinoma characterized by a reddish lesion, most often on the floor of the mouth.
• Verrucous carcinoma (Ackerman tumor)– this is an uncommon subtype of squamous cell carcinoma. It occurs mostly in people who chew tobacco or use snuff. Unlike basaloid squamous cell carcinoma, verrucous carcinoma is less aggressive, and has a good prognosis.
• Keratoacanthoma– this skin tumor is common in the elderly population; but it is less aggressive. Keratoacanthoma is characterized by rapidly growing red papule (A small solid circumscribed bump rising from the skin) over a few weeks to months.
• Clear cell squamous cell carcinoma(Clear cell carcinoma of the skin) –  this is a subtype of squamous cell carcinoma characterized by a clear discoloration of the keratinocytes, cells of the living epidermis and certain oral epithelia.
• Spindle cell squamous cell carcinoma– this is a rare microscopic subtype of squamous cell carcinoma characterized by spindle-shaped atypical cells;
• Basaloid squamous cell carcinoma– this type of squamous cell carcinoma is highly aggressive, and tends to occur in the tongue base, hypopharynx, and supraglottic larynx.
• Signet-ring cell squamous cell carcinoma– this is a highly malignant mucus-secreting tumor characterized by development in the skin of malignant cells having histologic appearance of signet ring cells.

Squamous Cell Carcinoma Incidence 

Incidence of squamous cell carcinoma is increasing. It is the most common skin cancer after basal cell carcinoma, which is the first most common form of non-melanoma skin cancer. Squamous cell carcinoma prevalence rates tend to vary from one country to another. The highest incidence of the disease occurs in Australia; age-adjusted incidence has been estimated to be 1332 cases per 100,000 population for men and 755 cases per 100,000 population for women.

In the United States, annual incidence of Squamous cell carcinoma ranged from 81-136 cases per 100,000 population for men and 26-59 cases per 100,000 population for women.  It is estimated that one in five Americans will develop skin cancer in his lifetime. Every year, more than 250,000 people are diagnosed with Squamous cell carcinoma in the United States; approximately 2,500 die of the disease.

Squamous Cell Carcinoma Causes 

The skin of an adult has an area of about 1.5 m2, a thickness of 1to 4mm. it is a resistant organ formed of about 2000 billion of cells which die periodically to be replaced by new healthy cells. The skin consists of three layers: epidermis, dermis and hypodermis.

The epidermis is the superficial layer of the skin that is in contact with the outside. It consists of three groups of cells: keratinocytes, melanocytes and Langerhans cells.

The Keratinocytes migrate to the surface of the skin and renew regularly. They are filled with highly resistant filaments (keratin) and lipids that provide resistance to external aggression. During their migration, these cells gradually flatten and eventually die on the surface of the skin to be replaced by new cells. Melanocytes, as a result of radiation, produce melanin, the pigment that provides color of many tissues including the skin. Langerhans cells, playing a role in the immune system, protect the skin from pathogens: chemicals, viruses, bacteria, allergic factors, etc. Langerhans cells also identify abnormal cells and trigger their elimination.

The dermis is located just below the epidermis. Being rich in collagen fibers, it provides the skin its strength and elasticity. It is in the dermis that skin cells born and multiply to replace dead cells. Unlike the epidermis, the dermis contains many blood vessels that provide nutrition to its cells and those of the epidermis. In addition, there are in the dermis nerves that are sensitive to touch, pain and temperature; that sensitivity allows protection and repair of damaged tissues.

The hypodermis is the deepest layer of the skin. It is rich in fat and blood vessels which allow it to absorb the pressures to which the skin is subjected. In addition, the hypodermis protects the body from temperature variations. The hypodermis is found mainly in parts of the body that withstand significant impact: buttocks, heels, etc.

The skin is constantly faced with aggression and pathogenic attacks. Thanks to its immunity and protective actions, the skin can repair itself as long these attacks are not too damaging. Squamous cell carcinoma occurs when the skin is unable to defend itself against carcinogenic attacks.

Usually, squamous cell carcinoma develops on precancerous lesions of the skin (actinic keratosis). Repeated or untreated papillomavirus (HPV) infection can also cause the development of squamous cell carcinoma. In addition, intense and prolonged exposure to sunlight can lead to development of squamous cell carcinoma in people of fair skin.

Squamous Cell Carcinoma Risk Factors 

• Age– squamous cell carcinoma affects mostly people aged 60 or over.
• Sex– men are more affected by squamous cell carcinoma than women.
• Certain occupation– people who have a profession which obligates them to work outdoors are at high risk of skin cancer including squamous cell carcinoma.
• Genetic– Some inherited conditions such as albinism and xerodermapigmentosum can be responsible for certain forms of squamous cell carcinoma.
• Therapeutic radiation –X-rays to the head or neck and certain treatments for psoriasis such as psoralen plus ultraviolet A (PUVA) can lead to development of squamous cell carcinoma, even years after the therapies.
• Toxic environment –certain chemical toxins such as arsenic – a toxic odorless and tasteless semi-metal element that can be found in air and groundwater – increases your risk of squamous cell carcinoma.
• Immunosupressant drugs –taking immunosupressant drugs is a major causative factor of squamous cell carcinoma.In fact, up to 80 percent of people who take immunosupressant medications after an organ transplant develop squamous cell carcinoma.

Other risk factors include: 

• fair skin
• blonde or red hair; blue or green eyes
• history of indoor tanning
• diagnosed with actinic keratoses (AKs)
• family history of skin cancer
• scar
• chronic ulcers
• severe burns
• regular contact with chemicals such as coal tar
• chronic consumption of alcohol and nicotine.

Squamous Cell Carcinoma Symptoms  

Squamous cell carcinoma tends to manifested, firstly, by flat reddish patches with a scaly brownish contour. When you scratch the lesion, it tends to bleed. Later, a growing bump that may have a rough, scaly surface can be formed. The parts of the skin most often affected by the tumor are sun-exposed areas: upper lip, scalp, external ear, back of hands and forearms, the ends of the feet and genitals.

In general, the appearance of the tumor is more or less rounded, regular or bumpy. Sometimes, the tumor is ulcerated. White-yellowish appearance can also develop on the edges.

Here are some guidelines that can help you differentiate a squamous cell carcinoma lesion from other less serious skin problems:

• the tumor develops in a pre-existing scar or ulcer
• the tumor commonly presents on sun-exposed areas
• the tumor bleeds intermittent, and does not want to heal
• the tumor has hard, raised edges
• the tumor grows relatively slowly
• clinical appearance of the tumor is highly variable
• the tumor tend to lie below the level of the surrounding skin
• development of a flat and white patch inside your mouth
• Occurrence of a sudden firm and red nodule on your face, lower lip, ears, neck, hands or arms.

Squamous Cell Carcinoma Complications  

If squamous cell carcinoma is diagnosed and treated early, the chances of recovery are very high. However, although it can be completely cured, squamous cell carcinoma can be aggressive if not treated early and effectively. In fact, the possibility of metastasis is estimated at 10% for squamous cell carcinoma of the sun-exposed areas.

Risk factors for recurrence or poor prognosis depends largely on your age, lifestyle, size and thickness of the tumor. Location of the cancer also plays a major role in the prognosis. Tumor of the retro-auricular region, eyelids, nasolabial folds, scalp, and extremities of hands and feet are most likely to recur or to spread to other sites. In general, the prognosis of squamous cell carcinoma located in the genital area or mouth is worse.

Squamous Cell Carcinoma Diagnosis 

Unlike many cancers, squamous cell carcinoma does not include many procedures. Your doctor will do a physical exam to examine your skin, especially the areas suspected to be affected by the cancer. Typically, your physician can diagnose the cancer with the naked eye. However, the diagnosis must be confirmed by a biopsy. Your oncologist or dermatologist will take sample from tumor for examination under a microscope. Histological examination of the sample will allow your physician to detect and identify the cancer cells in question.

Unlike many other types of cancer, squamous cell carcinoma may be suspected even in its genesis (carcinoma in situ). Therefore, it is important to report to your doctor any suspicious skin lesion; especially if the lesion is found in places that are frequently exposed to sunlight. In general, sores that last for six weeks should make you think of a squamous cell carcinoma.

In addition, your doctor can recommend an endoscopy, chest x-ray and CT of head and neck to detect metastasis or determine the stage of the cancer.

Squamous Cell Carcinoma Stages  

In general, squamous cell carcinoma develops in three stages:

• Stage I– at stage 1, the cancer remains superficially in the tissue where it originates. Your chance of surviving is very high
• Stage II– a stage 2 squamous cell carcinoma has infiltrated deeply into the tissue of the skin, and it is associated with a high risk of recurrence in cases of limited surgery. Loco-regional invasion may also occur, particularly in the pelvis. In addition, the cancer may have affected the bone tissue surrounding the tumor.
• Stage III– at this stage, the cancer has become more aggressive with high risk of lymph node metastases; your survival chance decreases significantly. Without a prompt and effective treatment, the cancer can travel through the bloodstream to form other tumor in surrounding or distant sites: lungs, liver, brain or bone.

Squamous Cell Carcinoma Treatment 

Squamous cell carcinoma treatment depends on several factors: clinical and histological characteristic of the tumor, your age and general health, other medications you are taking, etc. unlike many other cancers, squamous cell carcinoma is often diagnosed at an early stage. In fact, healing occurs in more than 90% of squamous cell carcinomas, when treated effectively.

The treatment of choice for squamous cell carcinoma is surgery. In case the lesion is extensive, and the surgery leaves scar, you will receive skin grafts. If you too fragile for surgery or the tumor is too bid to surgically removed, radiation therapy combined with local chemotherapy may be performed.

In general, treatment of squamous cell carcinoma includes surgery, electrocautery, cryosurgery, radiotherapy, chemotherapy and immunotherapy, and more recently photherapy.

Cryotherapy 

Also called cryosurgery, cryoablation or targeted cryoablation therapy, cryotherapy is the use or application of extreme cold to destroy diseased tissue, including cancerous cells. During the procedure, your physician uses a cryoprobe, a surgical instrument used to conduct intense cold to small areas of body tissues in order to destroy them. To position the cryoprobe precisely on the treated area, the therapist can use imaging techniques. He visualizes the movement of the device in real time on a monitor like a television screen.

Surgical Treatment

Surgery is the essential treatment for squamous cell carcinoma; In fact, most squamous cell carcinomas detected and removed early are successfully treated with surgery alone. It is estimated that 80% of skin cancers – when detected early – are effectively treated with surgery. Depending on the extension of the tumor, your surgeon can perform an excisional surgery, laser therapy, Mohs surgery or curettage.  

• Excisional surgery –this is, by far,the most common skin cancer surgical treatment. It consists of using a scalpel to remove cancerous tissue and a surrounding margin of healthy skin.
• Laser therapy –this method consists of using high-intensity light to kill cancerous tissue in order to shrink or destroy tumors.
• Mohs surgery –this surgical procedure is used to treat large basal cell carcinoma and squamous cell carcinoma. During the procedure, your surgeon removes the skin growth layer by layer, and immediately examines each layer under microscopeto search for cancer cells. 
• Curettage and electrodesiccation– this is a simple procedurepracticed, most of the times,to treat small basal cell and squamous cell tumors. It consists of removing the tumorfrom the skin with a curette, a surgical instrument designed for scraping biological tissue or debris.  After the tumor is removed, your surgeon will use an electric needle to cauterize the remaining cancer cells.

Chemotherapy  

Chemotherapy is an important tool in the treatment of advanced or metastatic skin cancer. It consists of using strong chemical agents to destroy cancer cells in the entire organism. Usually, chemotherapy drugs act by damaging cancer cells and preventing them from multiplying. The protocol varies depending on the stage of the cancer and your general health. In early stage cancers, creams or lotions containing anti-cancer agents can be used to kill the cancer cells. These chemotherapeutic agents can be administered alone or in combination. En general, the most effective therapeutic option will be considered.

Radiation Therapy (Radiotherapy)

Radiotherapy is a local therapy that treats a specific part of your body. The treatment consists of using ionizing radiation to destroy cancer cells in order to shrink or eliminate the tumor. Radiation is often practiced in advanced or metastatic skin cancer to relieve symptoms. Radiotherapy can be used in association with surgical therapy or alone when surgery is not an option.

Biological Therapy (Immunotherapy)

Biological therapy (immunotherapy) consists of using drugs to stimulate the immune system to help your body fight the cancer cells. Immunotherapy drugs act by activating your immune cells so they attack cancer cells and destroy them. Interferon and interleukin-2 are the two most used drugs in the treatment of skin cancer. Their common adverse effects include:

• chills
• fever
• fatigue
• headache
• muscle aches.

Photodynamic Therapy (PDT)

This new form of therapy involves application of a photosensitizing substance (causing susceptibility of tissue to certain lights) on the skin for several hours before exposing it to a blue or red light. The substance is applied on the skin as a liquid or a cream containing aminolevulinic acid (5-ALA-HCl) or methyl aminolevulinate (MAL). Once on the skin, the drug is absorbed by the diseased tissue and sebaceous glands. Exposure to the light activates the substance in the tissue, and causes its destruction. You will need to avoid direct sunlight for at least six weeks after treatment.

Other treatments 

Retinoids are often used in the treatment of squamous cell carcinoma (SCC). When they are used at high doses (3 to 4 mg / kg), they significantly reduce the size of large SCC. These drugs can be used alone or in combination with interferon. The combination of retinoids and interferon in the treatment of inoperable or advanced squamous cell carcinoma can provide satisfactory results. However, in some patients, retinoids often cause side effects:

• decreased appetite
• skin lesions
• hair loss
• liver problems
• eye problems
• bleeding
• general malaise,
• intracranial hypertension (BIH). 

Squamous Cell Carcinoma Prognosis 

Your chances of surviving a squamous cell carcinoma depend largely on the stage and size of the tumor. A tumor with a diameter greater than two centimeters and an invasion depth of more than 3 cm often has a poor prognosis. However, in most cases, squamous cell carcinoma prognosis is good. When treated early, the tumor is permanently cured in more than 90% of cases.

However, the survival rates tend to differ from one race to another. The overall 5-year relative survival rate for 1999-2005 from 17 SEER geographic areas was 91.1%. Five-year relative survival rates by race and sex were:

• 6% for white men;
• 7% for white women;
• 2% for black men;
• 1% for black women.

Squamous Cell Carcinoma Prevention 

If you’ve already been diagnosed with squamous cell carcinoma, regular medical checkups are necessary to prevent or treat recurrence. However, the most effective preventive measure is to avoid direct exposure to the sun by applying protective creams and wearing long clothing, hats, etc. In addition, the preventive measures can also help:

• Avoid tanning beds –tanning beds degage UVA rays that can penetrates into your skin and causes precancerous skin lesions; avoid them as long as you can.
• Get vitamin D safelythrough a healthy diet that may include vitamin D. If necessary, you can take vitamin D supplement.
• Regular skin check– check your skin regular to detect skin changes or changes in moles. This is even more important if you have been diagnosed with any form of skin cancer.
• Avoid sun exposure– prolonged exposure to sunlight and ultraviolet radiation is the main risk factor for melanoma; therefore, avoid them should be your first step if you really want to prevent squamous cell carcinoma. It is recommended to:
  • avoid sunbathing
  • wear protective clothing and hat when you walk under the sun
  • avoid sun exposure at times when solar radiation is high – usually between 10 am and 4 pm
  • Apply a protective sunscreen (20 index, at least) on your skin, and renew it every two hours and after swimming.