Brandon Skin cancers account for nearly one-third of all cancers diagnosed in the U. S. each year.1 This accounts for nearly 800,000 new cases each year.1 Squamous cell carcinomas develop in the thin, flat squamous cells that are found in the outer layer of the epidermis.2 Squamous cell carcinomas are known to be more aggressive than basal cell carcinomas and have a higher likelihood of spreading and metastasizing as well.
Etiology:
Brandon The main cause of squamous cell carcinoma is over exposure to UV radiation, especially if the use of sunscreen is not applied to the skin. Other risk factors that may lead to squamous cell carcinoma are:2
Fair skin (less melanin in the skin to help protect from UV rays)
The use of tanning beds
Blistering sun burns
Personal history of precancerous skin lesions
Weakened immune system
Signs & Symptoms:
Ashley Squamous cell carcinoma of the skin appears in a variety of ways. It can appear as a patch of irritated skin with rough or scaly characteristics. 3 It can also appear elevated and may grow over time. 1 In both cases, the lesion can bleed if irritated and become oozy and crusty. It can also appear as a scabbed-over wart. 3
Diagnostic Procedures:
Ashley The diagnosis of most skin cancers begins with a self-examination. Most patients will notice an abnormal growth. Once the patient reports the abnormality to their physician, the doctor examines the area and gets an extensive history to determine the likelihood of cancer development. 3 If the doctor suspects the lesion is suspicious, a biopsy is ordered to determine if a malignancy is present. 3
Histology:
Amanuel Histologically, squamous cell carcinomas of the skin demonstrate dermal invasion, pleomorphism of tumor cells, and presence of karatinization (may be absent in poorly differentiated type).4 Histologic subtypes include:5
Keratoacanthoma
Acantholytic
Spindle cell
Verrucous
Clear cell
Papillary
Signet ring
Pigmented
Desmoplastic
Lymph node drainage:
Amanuel Although still rare, squamous cell carcinomas spread more to lymph nodes than basal cell carcinoma.6 The drainage sites depend on the location of the original diagnosis.
Metastatic spread:
Lindsey Occasionally, squamos cell skin cancers do spread to other parts of the body, typically entering blood or lymph vessels.7 Lymph nodes are a common site of squamos cell metastasis.
Grading:
Lindsey If grading is not specified for a given tumor, the following system is commonly used:8 Gx: undetermined grade G1: well differentiated---low grade G2: moderately differentiated---intermediate grade G3: poorly differentiated---high grade G4: undifferentiated---high grade
Staging:
Kevin The American Joint Committee on Cancer’s (AJCC) TNM system is used to stage basal and squamous cell skin cancers.T= tumor size, location, and spread in to nearby tissues.9
TX: primary tumor can’t be assessed.
TO: no evidence of primary tumor
Tis: Carcinoma in situ
T1: Tumor is 2cm across or smaller and has only one high risk feature.
T2: larger than 2cm across or has 2 or more high risk features.
T3: Invades facial bones
T4: invades bones of the body or base of skull
High risk features of tumors that are used to distinguish T1 and T2
Thicker than 2mm
Invaded in to lower dermis or subcutis
Invaded tiny nerves if the skin
Originates from the ear or hair-bearing lip
Poorly differentiated or undifferentiated under microscope
N= Nodal involvement
NX: nearby nodes can’t be assessed
NO: No spread to nearby nodes
N1: 1 nearby node on the same side of the body as the primary and 3cm or less across
N2a: 1 node same side as primary and between 3 and 6cm across
N2b: more than 1 node on the same side as the primary, none larger than 6cm
N2c: spread to nodes on the opposite side of the body and none larger than 6cm
Erythema of the treated area is the earliest side effect
Dermatitis dependent of the dosage and energy used
Dry desquamation
Moist desquamation
Burning and itching symptoms
Radiation necrosis(usually in higher fractional doses)10
Prognosis:
Jenn Squamous cell carcinomas usually remain confined to the epidermis (top skin layer) for some time. However, the larger these tumors grow, the more extensive the treatment needed. They eventually penetrate the underlying tissues, which can lead to major disfigurement. A small percentage, about 2-5% spread metastasize to distant tissues and organs. When this happens squamous cell carcinoma can be life-threatening. About 2,500 deaths result each year in the U.S.11
Treatments:
Jenn Treatment options include:11
Mohs Micrographic Surgery: using local anesthesia the physician removes the tumor with a very thin layer of tissue around it. The layer is immediately checked under microscope thoroughly. If tumor is still present in the depths or peripheries of this surrounding tissue, the procedure is repeated until the last layer examined under the microscope is tumor-free.
Excisional Surgery; using local anesthesia, the physician scrapes off the cancerous growth with a sharp ring shaped instrument.
Radiation: may offer an advantage over surgical techniques with respect to cosmesis and function. Most skin cancers are treated with electrons. For most tumors, the electron beam energy is selected based on delivering the treatment to the 90% isodose line. Bolus is usually used to enhance surface dose. For more advanced lesions with deep penetration and involvement of bone or cartilage, photon beams with bolus can be employed in conjunction with electrons. Daily treatment fractions generally range from 50 to 60 Gy in 15 to 30 fractions over a period of 20 to 35 elapsed days for SCCs.
Cryosurgery: freezing with liquid nitrogen destroys tumor tissue, without the need for cutting or anesthesia. This is not used for invasive squamous cell carcinomas.
TD 5/5:
Rachel
The TD 5/5 for skin is 55 Gy.12 Telangiectasia and fibrosis are seen with doses to skin of over 45 Gy and are likely with doses over 65 Gy. Skin necrosis is the most severe late effect and is seen with doses over 55 Gy.
References:
Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 2nd ed. Philadelphia: Lippincott, Williams & Wilkins, 2002: 111.
Skin cancers account for nearly one-third of all cancers diagnosed in the U. S. each year.1 This accounts for nearly 800,000 new cases each year.1 Squamous cell carcinomas develop in the thin, flat squamous cells that are found in the outer layer of the epidermis.2 Squamous cell carcinomas are known to be more aggressive than basal cell carcinomas and have a higher likelihood of spreading and metastasizing as well.
The main cause of squamous cell carcinoma is over exposure to UV radiation, especially if the use of sunscreen is not applied to the skin. Other risk factors that may lead to squamous cell carcinoma are:2
Squamous cell carcinoma of the skin appears in a variety of ways. It can appear as a patch of irritated skin with rough or scaly characteristics. 3 It can also appear elevated and may grow over time. 1 In both cases, the lesion can bleed if irritated and become oozy and crusty. It can also appear as a scabbed-over wart. 3
The diagnosis of most skin cancers begins with a self-examination. Most patients will notice an abnormal growth. Once the patient reports the abnormality to their physician, the doctor examines the area and gets an extensive history to determine the likelihood of cancer development. 3 If the doctor suspects the lesion is suspicious, a biopsy is ordered to determine if a malignancy is present. 3
Histologically, squamous cell carcinomas of the skin demonstrate dermal invasion, pleomorphism of tumor cells, and presence of karatinization (may be absent in poorly differentiated type).4
Histologic subtypes include:5
Although still rare, squamous cell carcinomas spread more to lymph nodes than basal cell carcinoma.6 The drainage sites depend on the location of the original diagnosis.
Occasionally, squamos cell skin cancers do spread to other parts of the body, typically entering blood or lymph vessels.7 Lymph nodes are a common site of squamos cell metastasis.
If grading is not specified for a given tumor, the following system is commonly used:8
Gx: undetermined grade
G1: well differentiated---low grade
G2: moderately differentiated---intermediate grade
G3: poorly differentiated---high grade
G4: undifferentiated---high grade
The American Joint Committee on Cancer’s (AJCC) TNM system is used to stage basal and squamous cell skin cancers.T= tumor size, location, and spread in to nearby tissues.9
- TX: primary tumor can’t be assessed.
- TO: no evidence of primary tumor
- Tis: Carcinoma in situ
- T1: Tumor is 2cm across or smaller and has only one high risk feature.
- T2: larger than 2cm across or has 2 or more high risk features.
- T3: Invades facial bones
- T4: invades bones of the body or base of skull
High risk features of tumors that are used to distinguish T1 and T2- Thicker than 2mm
- Invaded in to lower dermis or subcutis
- Invaded tiny nerves if the skin
- Originates from the ear or hair-bearing lip
- Poorly differentiated or undifferentiated under microscope
N= Nodal involvement- NX: nearby nodes can’t be assessed
- NO: No spread to nearby nodes
- N1: 1 nearby node on the same side of the body as the primary and 3cm or less across
- N2a: 1 node same side as primary and between 3 and 6cm across
- N2b: more than 1 node on the same side as the primary, none larger than 6cm
- N2c: spread to nodes on the opposite side of the body and none larger than 6cm
- N3: any node is larger than 6cm across
M= Metastasis or spread to distant organshttp://www.cancer.gov/cancertopics/factsheet/detection/staging
Squamous cell carcinomas usually remain confined to the epidermis (top skin layer) for some time. However, the larger these tumors grow, the more extensive the treatment needed. They eventually penetrate the underlying tissues, which can lead to major disfigurement. A small percentage, about 2-5% spread metastasize to distant tissues and organs. When this happens squamous cell carcinoma can be life-threatening. About 2,500 deaths result each year in the U.S.11
Treatment options include:11
The TD 5/5 for skin is 55 Gy.12 Telangiectasia and fibrosis are seen with doses to skin of over 45 Gy and are likely with doses over 65 Gy. Skin necrosis is the most severe late effect and is seen with doses over 55 Gy.
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