An introduction to Basal Cell Carcinoma

Broadly speaking, skin cancer may be categorised into two main types – melanoma or non-melanoma. While melanomas are aggressive, malignant cancers that have a high potential of spreading to other parts of the body, non-melanomas are malignant cancers that have a low possibility of spreading to other parts of the body. Non-melanomas typically begin from either the basal cells or the squamous cells, in which case the disease is termed ‘Basal Cell Carcinoma’ or ‘Squamous Cell Carcinoma’ respectively.
Basal Cell Carcinoma falls under the category of non-melanoma skin cancer and is extremely common. In fact, there has been an alarming upsurge in the incidence of Basal Cell Carcinoma worldwide. Like Squamous Cell Carcinoma, Basal Cell Carcinoma arises from the most superficial layer of the skin, known as the epidermis. When the basal cells of the skin encounter some form of damage to its DNA, vital cell-signalling processes that tightly control the proliferation of these cells go haywire as well. Eventually, this culminates in an uncontrolled growth of basal cells, which raises the possibility of these accumulating abnormal cells becoming malignant. In the event that this does occur, a cancerous lesion then appears on the skin surface. Usually, Basal Cell Carcinomas are slow-growing tumours that rarely spread to other parts of the body. Although it is not immediately problematic, if neglected, Basal Cell Carcinomas can progress on to cause widespread destruction to the surrounding tissue and bone.

That is an unusual looking mole!

As a result of a convoluted interaction between various genetic and environmental factors, the external manifestation of Basal Cell Carcinoma differs between people. The head and neck region is where most of the tumours are sighted, while the trunk is the second most common area. While cancerous lesions may either appear as a collection of tumours or the development of tumours on the trunk area, the presentation of Basal Cell Carcinoma in the form of abnormal looking moles is of particular interest here. Unusual looking moles, such as moles that appear translucent with observable tiny blood vessels, or moles that are red, flat and appear scaly, as well as white/yellow moles that resemble scars, should raise some alarm bells.  White/yellow moles that resemble scars, in particular, are dangerous because they tend to surface only later and we often fail to notice them. What is more, they may indicate a highly infiltrative and aggressive form of Basal Cell Carcinoma.

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Who does Basal Cell Carcinoma affect the most?

A risk factor for developing Basal Cell Carcinoma is fair skin. As such, Caucasians face a higher risk of getting Basal Cell Carcinoma as compared to Asians, Hispanics and Blacks. Taking this closer to home, in Singapore, the Chinese have the highest risk as compared to the Malays and Indians simply because they have lighter skin. Apart from skin type, some other risk factors include: positive family history of skin cancer, the development of freckles in childhood, albinism and being under immunosuppressive therapy. Recent studies have also discovered that the risk of developing skin cancer is increased in the event that a gene, known as NLRP1, is defective. While it may be caused by genetic defects, Basal Cell Carcinoma may also be caused by environmental factors such as the exposure to ultraviolet radiation.

How is Basal Cell Carcinoma diagnosed?

While abnormal looking moles are a cause for concern, not all of them are necessarily a sign of skin cancer! It is important to consult a relevant medical professional to confirm the diagnosis. Usually, the process involves taking into consideration the patient’s medical history, a physical examination and some laboratory tests.

When investigating the patient’s medical history, relevant questions surrounding the suspicious skin lesion will be brought up. In addition, the patient will be asked if they have had skin cancer or any type of cancer before, as well as their knowledge of any family member who has/had cancer. As for the physical examination, the doctor will be observing the suspicious skin lesion(s) and other parts of the body to look out for any significant skin changes.

Should the suspicious skin lesion be a mole, it is vital to take into account some of its key characteristics such as: presence of asymmetry, the border, colour, diameter and evolution. Followed by this, the doctor typically recommends doing a skin biopsy of the suspicious lesion in order to test if this lesion is cancerous, and to also reveal the type of skin cancer.

When it comes to deciding the treatment plan for a patient with Basal Cell Carcinoma, there is a need to differentiate between new tumours and tumours that occur repeatedly. Apart from this, it is crucial to factor in the site, size and type of the cancerous lesion when settling on a certain plan of action.

What are the treatments available for Basal Cell Carcinoma?

There are a few options available when it comes to treatment plans, which could be broadly categorised into surgical and non-surgical procedures.

  • Among surgical procedures, surgical excision is a popular choice among doctors. This procedure involves surgically removing the entire cancerous lesion as well as a little of its peripheral healthy tissue, in order to ensure complete removal of cancerous cells. Doctors tend to opt for this option when the cancerous lesion is considerably big.
  • On the other hand, when the cancerous lesion is smaller in size and more superficial, cryotherapy and curettage can be considered. This process removes the superficial layer of the cancerous lesion first and then ends off by freezing the bottom of it using liquid nitrogen. In a similar procedure known as cryosurgery, liquid nitrogen is utilised to freeze and kill of cancerous cells. It proves effective in treating superficial Basal Cell Carcinomas as well.
  • Finally, for recurrent cancerous lesions, Mohs micrographic surgery may be a possible treatment option, which involves repeated excision of thin layers of cancer cells and observing it under the microscope until no more cancerous cells are found. This procedure has an edge over other surgical treatment options as it minimises the unnecessary removal of healthy tissue and does not compromise on the complete removal of cancerous cells from the patient. Mohs microsurgery is then usually followed up by radiation therapy.

Other than surgical treatment options, non-surgical treatments are an alternative as well.

  • Radiation therapy, for one, is a better choice for patients who are unable to undergo surgery for various reasons.
  • Additionally, imiquimod and fluorouracil are two FDA approved topical treatment options for superficial Basal Cell Carcinoma lesions. As previously mentioned, since post-transplant patients have a higher risk of developing Basal Cell Carcinoma, oral retinoid treatment can be given to such patients so as to minimise their risk.

While there are many possible courses of action for one to take, there is a risk of recurrence regardless of the patient’s choice of treatment plans. This is especially so for cancerous lesions which occur on the nose region. Furthermore, it is important to note that while Basal Cell Carcinoma rarely spreads to other parts of the body, patients have a heightened possibility of developing other forms of cancer such as Squamous Cell Carcinoma and Malignant Melanoma as well.


There is a substantial amount of pressure placed on healthcare services to accommodate the exponential incidence of Basal Cell Carcinoma worldwide. To prevent these numbers from increasing any further, there are a few ways to reduce the risk of developing Basal Cell Carcinoma. Some of them include minimising exposure to the sun, using sunscreen in order to protect oneself from ultraviolet radiation, as well as being more observant of unusual skin changes. It is wise to bring up any suspicious skin changes to a relevant medical professional and seek treatment for it promptly.