Squamous cell carcinoma (SCC) is the most common type of cancer of the conjunctiva in adults. However, it is still an uncommon cancer.
Squamous cells are the flat, thin cells that cover many of the outer and inner surfaces of the body. SCC of the conjunctiva tends to occur in older people (the average age of diagnosis is 60 years). It also occurs more often in men than in women. This may be because jobs that tend to expose people to sunlight over long periods of time are typically done by men. People with AIDS have an increase risk of developing certain cancers, including SCC of the conjunctiva.
Signs and symptoms
The tumours often appear in the area closest to the nose or temple. They can occur in various forms:
- a white, flesh-coloured or red patch
- a rounded, elevated growth
- growths that have a gel-like appearance
These tumours can cause eye irritation or chronic conjunctivitis (inflammation of the conjunctiva). Squamous cell carcinoma should be considered in cases of conjunctivitis that lasts longer than 3 months. Squamous cell carcinomas can often mimic a pterygium, which is a benign growth of the conjunctiva.
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Grading is a way of classifying conjunctival cancer cells based on their appearance and behaviour when viewed under a microscope. The grade of squamous cell carcinoma of the conjunctiva is based on how different cancer cells look and act compared with normal cells (differentiation) and their rate of growth.
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Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. The most common staging system for conjunctival squamous cell carcinomas is the TNM system. The International Union Against Cancer (UICC) uses the TNM system to describe the extent of many solid tumour cancers.
The following TNM staging is used for squamous cell carcinoma of the conjunctiva. Melanoma of the conjunctiva and lymphoma of the conjunctiva are staged differently.
TNM stands for tumour, nodes, metastasis. TNM staging describes:
- the size of the primary tumour
- the number and location of any regional lymph nodes that have cancer cells in them
- whether the cancer has spread or metastasized to another part of the body
Primary tumour (T)
No evidence of primary tumour
Carcinoma in situ
Tumour is 5 mm (0.2 inch) or less in size.
Tumour is more than 5 mm in size, but has not grown into nearby structures.*
Tumour has grown into nearby structures.
Tumour has spread to the orbit or structures beyond the orbit.
T4a – Tumour has spread to the soft tissues of the orbit but not the orbital bone.
T4b – Tumour has spread into the bone.
T4c – Tumour has spread into the paranasal sinuses.
*Note: Nearby (adjacent) structures include the cornea, intraocular compartments, forniceal, palpebral and tarsal conjunctiva, lacrimal punctum and canaliculi, plica, caruncle, posterior eyelid lamella, anterior eyelid lamella, and the eyelid margin. The extent of the tumour on the cornea is measured by clock hours. The cornea is divided into 12 sections, similar to the face of a clock. The clock can also be divided into 4 parts (quadrants) that correspond to 3, 6, 9 or 12 clock hours. These sections are used to determine the amount of conjunctival tumour that has grown into the cornea.
Regional lymph nodes (N)
No regional lymph node metastasis
Note: The regional lymph nodes include those around the ear (preauricular nodes), lower jaw (submandibular nodes) and neck (cervical nodes).
Distant metastasis (M)
There is no stage grouping for conjunctival squamous cell carcinoma.
Recurrent conjunctival squamous cell carcinoma
Recurrent conjunctival squamous cell carcinoma means that the cancer has come back after it has been treated. It may recur in the same location as the original cancer or it may recur in another part of the body (metastatic conjunctival squamous cell carcinoma).
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The prognosis is generally good if the conjunctival tumour can be completely removed. Squamous cell carcinomas of the conjunctiva are usually on the surface of the conjunctiva (superficial invasion), but can sometimes grow into the eye and orbit. The cancer can spread into regional lymph nodes, but this is not very common.
The mortality rate (the number of people who die from the disease each year) is generally low (about 4%–8% of people with squamous cell carcinoma of the conjunctiva die from this disease).
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The treatment for squamous cell carcinoma of the conjunctiva is complete removal of the tumour with surgery. Sometimes the cornea will need to be treated. If the tumour has grown into the orbit of the eye, then exenteration may be needed. Reconstruction of the conjunctiva may be required, depending on the amount of tissue removed. This may include using grafts of nearby tissue for reconstruction.
Squamous cell carcinoma of the conjunctiva can recur following surgery. Additional (adjuvant) treatment is often used after surgery to lower the risk of recurrence and may include:
- radiation therapy
- Brachytherapy may be used to treat tumours that cannot be completely removed by surgery or tumours that come back (recur).
- topical chemotherapy
- The drugs used most often for topical chemotherapy include mitomycin (Mutamycin) and 5-fluorouracil (Adrucil, 5-FU) eye drops.
- For more detailed information on specific drugs, go to sources of drug information.
Radiation therapy may also be used to relieve symptoms (palliative therapy) in cases where the person cannot tolerate surgery.
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