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Skin cancer: What lies beneath

Parkway Cancer Centre’s Dr Edward Yang Tuck Loong answers some questions about melanoma skin cancer and the role of radiation therapy in treatment.

What is melanoma skin cancer?

Most skin cancers start in the top layer of the skin called the epidermis. Within the epidermis are squamous cells, basal cells and melanocytes. When a skin cancer becomes more advanced, it generally grows through these layers of cells into the deeper layers of the skin.

Melanoma skin cancer, however, begins in the melanocytes. Melanocytes are responsible for producing the brown pigment called melanin which gives the skin its tanned colour and protects the deeper layers of the skin from some of the harmful effects of the sun. When melanocytes start to grow out of control, it becomes cancerous.

Melanomas are more likely to develop from the trunk (chest and back) in men and on the legs in women. Other common sites include the neck and face.

While melanoma is much less common than some other types of skin cancers, it is much more likely to spread to other parts of the body if not caught and treated early.

Melanoma is rare among Asians and afflicts Caucasians exposed to excessive sunlight.

What causes melanoma skin cancer?

There are many risk factors for melanoma skin cancer. They include prolonged exposure to ultraviolet (UV) rays, being fair-skinned, having many moles, skin that freckles easily, a family history of melanoma. It is not fully conclusive, however, of exactly how these factors can cause cancer.

For example, most moles do not cause a problem, but some do develop into melanoma. While some research have found gene mutations inside mole cells that may cause them to become cancerous, it still cannot be explained why some cells do not become mutated.

As gene mutations can be acquired or inherited, risk factors can only provide a glimpse of possible cancer causes and things that a person can do to lower his or her risk of getting melanoma.

How is the cancer detected?

Early detection of melanoma skin cancer can increase the chance of a person making a full recovery, particularly for Stage 1 melanoma. For example, regular checking for new or suspicious spots on one’s skin, or any spots that are changing, itching or bleeding.

The ABCDE guide by the American Academy of Dermatology is another useful guide to detect signs of melanoma:

• Asymmetry: Is one half of a mole unlike the other half?
• Border: Does a mole have an irregular, scalloped or poorly defined border?
• Colour: Is there more than one colour in a mole, such as shades of tan and brown, black, white, red or blue?
• Diameter: Is a mole bigger than 6mm (the size of a pencil eraser)? Melanomas are usually bigger than 6mm when diagnosed, but they can be smaller.
• Evolving: Does a mole or another spot on the skin look different from the rest? Is a mole or another spot changing in size, shape or colour?

What is the role of radiation therapy in treating melanoma skin cancer?

For very early stage melanomas, radiation therapy can be an option if surgery cannot be done for some reasons. At other times, radiation therapy can be given after surgery to lower the chance of the cancer recurring, such as after the removal of lymph nodes.

Radiation therapy can also be used to improve the quality of life and allow better management of symptoms after the spread of melanoma to the brain, bones or other parts of the body.

Such treatment is known as palliative radiation therapy. It is aimed at slowing the growth of the cancer and alleviating the symptoms that patients may experience due to cancer metastasis.

Radiation therapy can be delivered over a number of sessions. It is usually done five days a week, for a period of anywhere from one to six weeks.

What are the side effects?

The side effects of radiation therapy are usually short term, and patients will feel better as they progress in the treatment. Common side effects include changes in skin colour, hair loss and fatigue. There may also be other site-specific side effects, for example, headaches when the brain area is treated or nausea when the abdomen is treated.

What happens after radiation therapy?

Completing the treatment often brings about a mixture of feelings as it could mean recovery, a need to extend treatment, or consider other options. It can also be difficult not to worry about the cancer recurring.

In some cases, melanoma may never go away completely. As such, immunotherapy, targeted therapy, chemotherapy, or other treatments may be used to control the cancer growth for longer periods.

It is possible to learn to live with melanoma that does not go away by staying positive, seeking support from family members and friends, getting help from a professional counsellor or joining a cancer support group.

Follow-up appointments after the cancer treatment is completed are important for close monitoring.

During these appointments, your doctor may require you to do some lab tests, scans and physical examinations to check your health status, look out for signs of new skin abnormalities, or to manage the side effects of treatment.

This is a good chance for you to ask questions, discuss your concerns, or talk about any changes that you may have noticed.

More common than you think

Skin cancer is one of the top 10 most frequent cancers in Singapore. And the incidence of this cancer in both men and women has been rising over the past 40 years.

SINGAPORE

6th most common cancer in men
7th most common cancer in women

WORLDWIDE

19th most common cancer

Types of skin cancer

Melanoma skin cancer: Begins in the melanocytes, the cells that give the skin its tanned colour.

Non-melanoma skin cancer (NMSC): Consists of squamous cell carcinoma and basal cell carcinoma, and develops from skin cells.

Causes

Ultraviolet (UV) radiation from the sun is the most important risk factor of melanoma skin cancer and NMSC. About 90 per cent of NMSC are caused by sun damage or simply too much sun.

Prevention

• Avoid the sun as much as possible.
• Stay protected: Wear a hat, use an umbrella, apply sunscreen, cover up with clothing.