What are the other Names for this Condition? (Also known as/Synonyms)

• Post-Radiation Squamous Cell Carcinoma
• Radiation Scar Carcinoma
• SCC arising in Radiation Scar

What is Squamous Cell Carcinoma arising in Radiation Scar? (Definition/Background Information)

• Squamous Cell Carcinoma (SCC) arising in Radiation Scar is an uncommon malignant tumor of skin that typically arises due to previous radiation treatment for other health conditions
• The radiation treatment could lead to the formation of severe scars on skin. Other factors that may influence its development include sun’s ultraviolet rays, skin tanning, and exposure to coal tar and arsenic
• Squamous Cell Carcinoma arising in Radiation Scar may appear as slow-growing skin lesions; the formation of the lesion may take several years. It is more aggressive than conventional squamous cell carcinoma affecting other body regions
• The treatment of choice is a surgical excision with clear margins followed by radiation therapy or chemotherapy, as decided by the healthcare provider. In majority of the cases, the prognosis is improved with appropriate early treatment
• Nevertheless, the prognosis of Squamous Cell Carcinoma arising in Radiation Scar depends upon many factors including the stage of the tumor and health status of the affected individual. There is a possibility of local or regional metastasis, which can involve the lymph nodes. This may dictate the course of the condition

Who gets Squamous Cell Carcinoma arising in Radiation Scar? (Age and Sex Distribution)

• Squamous Cell Carcinoma arising in Radiation Scar can potentially affect individuals of any age, who underwent radiation therapy for other health issues. However, it is commonly seen in adults
• It can occur in both males and females
• The condition is prevalent worldwide, though dark-skinned individuals (Asians and Africans) are affected less than lighter-skinned individuals (Europeans and Americans)

What are the Risk Factors for Squamous Cell Carcinoma arising in Radiation Scar? (Predisposing Factors)

A history of radiation therapy that results in severe scarring of the skin can lead to the formation of squamous cell carcinoma at the affected (radiation) site. Nevertheless, other factors may contribute towards the development of Squamous Cell Carcinoma arising in Radiation Scar. These include:

• Exposure to intense sun for long periods during the course of work or due to regular participation in outdoor sports activities
• Frequent use of tanning beds, tanning parlors
• People living in geographical regions where hot-dry, desert-like climatic conditions prevail
• Arsenic exposure
• Coal tar exposure
• Smoking, tobacco chewing
• Individuals with weak immune system, which could be due to cancer treatment or AIDS, or those on immunosuppressant drugs after receiving an organ transplant
• Those with sensitive skin, who are easily sunburned
• Caucasians are more vulnerable compared to other darker-toned individuals

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Squamous Cell Carcinoma arising in Radiation Scar? (Etiology)

• Squamous Cell Carcinoma arising in Radiation Scar occurs when skin cells (the keratinocytes that form the epidermis) are burnt or damaged from prolonged and frequently severe exposure to (prior) radiation that is administered for treatment/therapeutic purposes. This causes DNA damage that results in a malignant transformation of the affected skin
• In order for Post-Radiation Squamous Cell Carcinoma to arise, the radiation therapy has typically  resulted in severe scars. Minor or mild cases of radiation usually does not lead to carcinoma development
• The effect of ultraviolet sources, such as the sun and tanning lamps, on the affected radiation site may cumulatively contribute towards skin damage
• Sometimes, individuals working in certain industries may be exposed to chemicals or X-rays for a long duration. This may also contribute to the formation of this skin cancer type
• Scientific research has indicated that the human papillomavirus along with other risk factors, such as sun-exposure, skin color, and an advancing age, seem to greatly multiply the chances of an individual being affected by SCC arising in Radiation Scar. Nevertheless, the reason behind how the virus is responsible for influencing the condition’s development is not well-established

What are the Signs and Symptoms of Squamous Cell Carcinoma arising in Radiation Scar?

The signs and symptoms of Squamous Cell Carcinoma arising in Radiation Scar include:

• In majority of the cases, the SCC is asymptomatic and does not present any signs or symptoms (during the initial period)
• Generally, it is a slow-growing tumor that develops over a prolonged period (may be even many years)
• The skin lesion develops at the site of administration of radiation
• The skin lesions may appear as crusted ulcer, plaques, and nodules
• It may ulcerate and bleed. Occasionally, after the ulcer heals, it may become ulcerated again
• The size of the lesions range from 1-10 cm; average size is usually less than 3 cm
• In some cases, the squamous cell carcinoma may appear more pigmented than the surrounding skin
• Individuals with immunocompromised states have more aggressive tumors

How is Squamous Cell Carcinoma arising in Radiation Scar Diagnosed?

A diagnosis of Squamous Cell Carcinoma arising in Radiation Scar is made by the following tests and exams:

• Complete physical examination with detailed medical history evaluation (including history of previous radiation therapy)
• Examination by a dermatologist using a dermoscopy, a special device to examine the skin
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment.

Tissue biopsy:

• A tissue biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
• Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
• Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

In case of metastatic SCC, the following diagnostic procedures can be used to procure the tissue sample:

• Fine needle aspiration (FNA) biopsy of the tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
• Core biopsy or open biopsy of the tumor

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Squamous Cell Carcinoma arising in Radiation Scar?

The possible complications due to Squamous Cell Carcinoma arising in Radiation Scar include:

• Discomfort, irritability of the affected skin
• Large lesions may ulcerate and bleed resulting in superimposed bacterial or fungal infections
• Permanent scarring might occur with SCC and plastic surgery may be required to restore the function and appearance of the local skin
• They can metastasize to the lymph nodes
• Tumors that invade into nerves (perineurial invasion) have higher chances of recurrence and metastasis
• Tumors that are over 2 cm in size have a higher incidence of recurrence and metastasis, than tumors that are less than 2 cm in size

How is Squamous Cell Carcinoma arising in Radiation Scar Treated?

Early diagnosis and treatment of Squamous Cell Carcinoma arising in Radiation Scar is important to avoid complications such as metastasis to other regions. The treatment measures may include:

• In most cases, a wide surgical excision and removal of the entire tumor is the preferred treatment option. This may be followed by radiation therapy and/or chemotherapy
• Mohs micrographic surgery can be used for the removal of Squamous Cell Carcinoma arising in Radiation Scar
• If the tumor has metastasized (in rare cases), then a combination of chemotherapy, radiation therapy, and invasive procedures may be used to treat the tumor
• Targeted therapy medications are generally used for locally infiltrated or metastatic SCCs. This therapy destroys the tumor cells by acting against the proteins that are responsible for tumor growth
• Use of photodynamic light or laser therapy: Light destroys the damaged cells after they are treated with a special medical application
• Cryotherapy: Controlled use of liquid nitrogen, to force spontaneous peeling, and removal of skin
• Large tumors following complete skin excision may need skin grafting
• Post-operative care is important: One must maintain minimum activity levels until the surgical wound heals

Follow-up care with regular screening and check-ups are important and highly-recommended.

How can Squamous Cell Carcinoma arising in Radiation Scar be Prevented?

It may not be possible to prevent Squamous Cell Carcinoma arising in Radiation Scar. However, the following contributing factors may be avoided and these include:

• Prolonged and chronic exposure to the sun: If this is unavoidable (like due to an occupational requirement), then take safety steps to reduce exposure to UV rays by using sunscreens with high sun-protection factor, wide-brimmed hats, and protective clothing
• Be aware of the hazards of prolonged sun exposure and take steps to protect yourself. Plan and modify your work tasks to stay out of the sun during the period when it is at its most intense
• Avoid excessive sunbathing (particularly if you are fair-skinned), use of tanning beds, sun lamps, and chemical agents that accelerate sun tanning
• Individuals, who are regularly exposed to the sun or work under the sun, should get their skin periodically examined by a physician. This is especially important if they suspect or notice any skin changes

Regular medical screening at periodic intervals with blood tests, scans, and physical examinations are mandatory, due to its high metastasizing potential and possibility of recurrence. Often several years of active vigilance is necessary.

What is the Prognosis of Squamous Cell Carcinoma arising in Radiation Scar? (Outcomes/Resolutions)

In general, Squamous Cell Carcinoma arising in Radiation Scar is an aggressive form of skin cancer. If metastasis (such as to the local lymph nodes) is observed, then the prognosis may be guarded or unpredictable.

• Tumors in their early stage with complete excisional treatment typically have good prognosis
• In cases of metastasis, its prognosis depends upon a set of several factors that include:
  • Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
  • The surgical resectability of the tumor (meaning if the tumor can be removed completely)
  • Overall health of the individual: Individuals with overall excellent health have better prognosis compared to those with poor health
  • Age of the individual: Older individuals generally have poorer prognosis than younger individuals
  • Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have a poorer prognosis compared to tumors that do not recur
  • Response to treatment: Tumors that respond to treatment have better prognosis compared to tumors that do not respond so well to treatment

Additional and Relevant Useful Information for Squamous Cell Carcinoma arising in Radiation Scar:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/cancer/