Basal-Cell Carcinoma: Prevention and Treatment

Interview with Dr. Thomas G. Salopek, MD, FRCPC

Professor, Department of Medicine, Division of Dermatology & Cutaneous Sciences, University of Alberta, Edmonton, AB

Dr. Salopek has been recognized for his revolutionary, multidisciplinary skin cancer clinic and currently heads up the Provincial Cutaneous Tumour Group, a group that drafts guidelines for the management of skin cancers in Alberta. 

1. What types of skin cancer should we be worried about?

There are basically two broad groups of skin cancer: melanoma and non-melanoma. Melanoma is a rarer but more lethal form that, like all skin cancers, is nonetheless preventable and treatable  Non-melanoma skin cancer includes two types: basal-cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC is approximately three times more prevalent than SCC.  Squamous-cell carcinoma like BCC primarily occurs in sun-exposed areas but can also occur in protected sites such as the mouth or genitals, and is more likely to metastasize (spread to other parts of the body). In contrast, most BCC tumours are found on the head or neck and rarely lead to death.

Why should we worry about BCC? First, BCC is exceedingly common.  Second, if it is not caught and treated early, BCC can be destructive and/or disfiguring, either as a result of the cancer itself or from its treatment. For example, a patient can lose an eye or ear because of the disease or surgical treatment. When caught in time, however, BCC can be treated with minimal consequences. It's best, however, to prevent BCC.

2. What can patients do to prevent skin cancers?

Although skin cancers have a number of causes, including exposure to radiation and other carcinogens and use of immunosuppressants (drugs that act to repress the body’s immune response), by far the leading cause of skin cancer is exposure to the sun. It is true that some non-melanoma skin cancers are related to certain occupations (for example, people in the gold mining industry are exposed to arsenic). The number of people in these occupations is small, as such they only account for a small proportion of skin cancers.  Given that it is not possible - or desirable - to avoid the sun completely, we should all take steps to minimize the time we spend in the sun. We can prevent skin cancers by avoiding extended sun exposure, cover up with protective clothing when practical, and using sun screens (SPF 30 or higher), especially when we are young. Unlike melanoma which often presents earlier in life, BCC usually occurs later in life, almost always after 40 years of age. In fact, there seems to be a lag between sun exposure earlier in life and the appearance of BCC which "takes off" at about age 40 and increases through to age 80. Even though BCC occurs late in life, prevention must begin in the early years. Development of BCC - and skin cancers, generally - can't be reversed. The stage is set for all skin cancers in the teen years. 

3. What are the risk factors for developing BCC?

Skin cancers in general are increased for those with fair skin, blue eyes and blond hair who are more prone to sun burn. Working outdoors increases risk, as does using a tanning salon and tanning outside for extended periods, especially while on vacation. Risk also increases with the number of sunburns a person experiences - cumulative sun exposure makes a difference.

4. What happens if BCC is left untreated? Can BCC be deadly?

As already indicated, BCC rarely leads to death because its development can be arrested with treatment and there is a high cure rate. On the rare occasion when BCC metastasizes, it almost always leads to death. Significant morbidity only occurs when an aggressive tumour gnaws away at vital structures such as an eye or ear, usually as a consequence of neglect of the tumour over many years. In these circumstances, BCC can cause disfigurement, loss of function and reduced quality of life. Quality of life is usually not significantly affected if BCC occurs on the trunk, but when it affects areas of the eye, ear, mouth or nose - as it commonly does - then functional impairment significantly affects quality of life.   

5. How is BCC treated?

In the vast majority of cases, BCC is easily treated with various surgical procedures. In select patients with small, thin BCCs topical agents may be effective.  For most patients, success rates are very high. Treatments include:

  • Surgery - Surgery is the most common form of treatment and usually results in minimal disfigurement. There are three types of surgery:
    • Excisional biopsy - a standard procedure where the surgeon removes the entire tumour with a small amount of surrounding normal skin tissue to ensure its complete removal;
    • Curettage & electrodessication – removal of the tumour by scraping off the cancer followed by cauterization of the base; and,
    • Mohs micrographic surgery - a precise form of excision where the surgeon also functions as a pathologist and assesses the adequacy of his/her excision microscopically during the procedure.
  • Cryotherapy or Freezing – This procedure is an older treatment modality that is still utilized but is not considered to be ideal. The rate of failure is high since it may not completely destroy the tumour.
  • Radiation Therapy - Radiation is used when the tumour is very large, or if surgery is deemed too disfiguring, or if the patient is not fit medically to endure the procedure.

Two new Therapies –

  • Photo Dynamic Therapy – Photo dynamic therapy is administrated by application of photosensitizers to the target area. These molecules are selectively taken up by cancerous cells  and when activated by light, they become toxic to the target cells. This therapy is still evolving and is not readily available in Canada.
  • Oral Therapy - Oral agents are currently under investigation for very advanced tumours.

6. Why is a new treatment option especially important for advanced BCC?

Patients with locally advanced or metastatic BCC that cannot be treated with conventional therapies like surgery or radiation, have few treatment options. New pharmaceutical options offer promise that a systemic agent working at the cellular level can shrink or stabilize BCC tumours. Research continues into this important new treatment option for patients who lack alternative treatment modalities.