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Basal cell carcinoma skin cancer

 
Basal cell carcinoma is the most common yet least dangerous type of skin cancer. There is a range of characteristic symptoms of basal cell carcinomas and effective treatment options that, if the disease is identified early, can have excellent outcomes.

General information

Skin cancers are named after the type of skin cells from which they originate. Basal cell carcinomas (BCC) arise from basal cells in the lower layers of the skin (in contrast to melanoma skin cancers that arise in the skin's pigment-producing cells, called melanocytes).

BCC occurs when a basal cell develops a mutation in its DNA (genetic information). One of the primary causes of damage to DNA in basal cells is ultraviolet (UV) radiation found in sunlight (and in tanning beds). However, other factors can also contribute to the development of BCC.

People with BCCs are likely to develop further BCCs and are at increased risk of other skin cancers, including melanoma. It most commonly occurs in people with fair complexions (fair skin, blue eyes, and blonde or red hair) particularly those who have had considerable exposure to the sun or have had repeated sunburn. It is also thought that the tendency to develop BCCs may run in families. 

It is rare for BCCs to affect the lymph nodes or blood. However, if left untreated, they can invade localised structures such as the eyelids, nerves, cartilage or bone.

Symptoms

BCCs most frequently occur on the face, ears, neck, back of the hands, arms and shoulders. They occur equally in both men and women and most commonly affect people over the age of 40 years. BCCs are typically slow growing (months or years). In general terms, BCCs appear as a change in the skin, such as a growth or a sore that does not heal.

Characteristic features of BCCs may include:

  • A few millimetres to several centimetres in diameter
  • Waxy small, raised lesions (papules) with a depressed centre
  • Pearl-like and translucent in appearance
  • Ulcer-like in appearance
  • Tendency to bleed
  • Red and scaly, oozing or crusted areas
  • Raised borders
  • Black-blue or brown areas.

Diagnosis

If a change or abnormality (lesion) develops on the skin it is important to consult a doctor as soon as possible for a diagnosis to be made. The doctor will look closely at the lesion, assessing its size, location and characteristics and will ask about the history of the lesion eg: how long it has been there, whether it bleeds or itches etc.

If the doctor suspects that the abnormal lesion may be cancerous, they may take a small sample of the tissue (a biopsy). The sample of tissue is sent to a laboratory where examination under a microscope can reveal whether the tissue cells are cancerous. If they are then the doctor will recommend appropriate treatment. 

Treatment

The treatment of a BCC will depend on its type, size and location. Early treatment will lessen scarring and local complications. A combination of treatments is often used. Treatment options include:

Excision

This is the most common treatment for BCC. Excision involves cutting out the BCC along with a small area of surrounding tissue and stitching up the skin. In many cases, this can be done by a GP. For larger, more extensive BCCs (particularly if they are in a difficult position) a referral to a plastic surgeon or other appropriate specialist may be required. After excision of the BCC a graft or skin flap may be used to repair the defect.

Mohs surgery

This surgical technique enables BCCs, and other skin cancers, to be more precisely but completely excised whilst preserving as much healthy skin tissue as possible. During surgery, an initial excision is made and the tissue is carefully examined under a microscope. If necessary, further slices of tissue are removed until it is clear on microscopic examination that all the cancer has been removed. Mohs surgery is performed under local anaesthetic by a dermatologist who has special training in the technique. 

This technique is not appropriate for the treatment of all skin cancers. Mohs surgery is mainly indicated in the treatment of BCC and squamous cell carcinoma (skin cancer that forms in the squamous cells that are located at the top of the epidermis) that are in areas of the body where preservation of surrounding tissues avoids the need for complex reconstructions. However reconstructive surgery may be required occasionally after Mohs surgery. The technique is not appropriate for melanoma skin cancers.

Freezing (Cryotherapy)

This treatment uses liquid nitrogen to freeze off the BCC. This is used in the treatment of superficial BCCs only.

Curettage or shaving

This treatment uses specialised cutting instruments to remove the BCC layer by layer.

Radiotherapy (radiation therapy)

X-ray treatment to destroy the BCC may be used for lesions on the face or for lesions that are inoperable. This form of treatment is not usually recommended for people under the age of 65 years.

Photodynamic therapy

A special cream is applied to the BCC and the lesion is exposed to a special light (either laser or non-laser) several hours later. A chemical reaction between the cream and the light kills the cancer cells but not healthy cells.

Topical medications

Imiquimod cream is a prescription medication that works by stimulating the immune system to release chemicals that help to destroy the cancer cells. Fluorouracil cream, also a prescription medication, kills cancer cells.  Both topical medications are mainly used against small superficial BCCs.

Prevention

Avoiding exposure to the sun is the best way to reduce the risk of developing a BCC. If exposure to the sun is unavoidable the Cancer Society of New Zealand recommends the following precautions:

  • Use a sunscreen that has sun protection factor of at least SPF30
  • Wear a wide brimmed hat, protective clothing and sunglasses
  • Avoid being out in the sun between 11am and 4pm
  • Seek shade eg: from trees, umbrellas, buildings, canopies and marques
  • Avoid tanning beds, which emit UV radiation that can increase the risk of skin cancer.

It is also recommended that you check your skin every 3–6 months for changes in moles or freckles. Early detection is very important and if any changes are noticed, consult a doctor.

References

Cancer Society (2020). About skin cancer (Web page). Wellington: Cancer Society of New Zealand. https://auckland-northland.cancernz.org.nz/reducing-cancer-risk/what-you-can-do/sunsmart/about-skin-cancer/#Types [Accessed: 17/11/20]
Bader, R.S. (2020). Basal cell carcinoma (Web page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. https://emedicine.medscape.com/article/276624-overview [Accessed: 17/11/20]
Mayo Clinic (2019). Basal cell carcinoma (Web page). Rochester, MN: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/basal-cell-carcinoma/symptoms-causes/syc-20354187 [Accessed: 17/11/20]
Oakley, A. (2015). Basal cell carcinoma (Web page). Hamilton: DermNet New Zealand. https://www.dermnetnz.org/topics/basal-cell-carcinoma/ [Accessed: 17/11/20]
O’Toole, M.T. (Ed.) (2017). Basal cell carcinoma. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier Mosby.

Last Reviewed: November 2020

 
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