The two main types of NMSC are basal cell carcinoma and squamous cell carcinoma.
The warning sign of MSC is a new spot on the skin or a spot that is changing in size, shape or colour.
Dr Zee Ying Kiat
IN equatorial countries such as ours, the weather is hot and humid – very often swelteringly so.
Under such parching conditions, the effects – at least the ‘milder’ ones – of going outdoors and staying in heat of the sun unprotected are dry skin and sunburn but be warned – long-term exposure to the sun’s ultra-violet (UV) light can lead to skin cancer.
“Excessive sun exposure is the major carcinogenic risk to the skin. Specifically, the UV radiation in sunlight can damage the DNA of genes that control skin cell growth, leading to cancerous change,” Dr Zee Ying Kiat, a specialist in Medical Oncology, told The Borneo Post.
He said fair-skinned people or those more likely to burn than tan were at greater risk of skin cancer because their skin made less of the protective pigment called melanin, whereas dark-skinned people were less likely to get skin cancer although they could be at particular risk in areas not exposed to the sun such as the palms of the hands and soles of the feet.
According to Dr Zee, who practises at Parkway Cancer Centre (PCC), Singapore, other risk factors include age, personal history of skin cancer, family history of skin cancer, infection with human papilloma virus (HPV), previous treatment with radiotherapy, exposure to certain chemicals, and a weakened immune system.
Preventive measures
Although skin cancers might sound scary, he assured most were preventable. Among the preventive measures are avoidance of excessive sun exposure, use of protective clothing, hats and sunglasses and application of sunscreen.
Dr Zee said aside from external means, it was also possible to obtain protection through dietary habits although this was yet to be conclusively established.
“While several studies have looked at antioxidants, folic acids, fats and proteins as well as variety of whole foods, the results are not entirely conclusive. More importantly, it’s vital to maintain a balanced diet,” he added.
Skin cancer types
Skin cancer can be broadly divided into non-melanoma skin cancer (NMSC) and melanoma skin cancer (MSC).
Dr Zee noted that the incidence of both NMSC and MSC had been increasing over the past decades “which is kind of worrying.”
The two main NMSC types are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Roughly, eight out of 10 NMSC cases are BCC while two out of 10 are SCC.
He said based on World Health Organisation (WHO) figures, between two and three million NMSC cases and 132,000 MSC cases occurred globally each year.
“In fact, NMSC is by far the most common type of cancer worldwide,” he stressed.
The warning sign for melanoma is a new spot on the skin or a spot that is changing in size, shape or colour. Another important sign is a spot that looks different from all of the other spots on the skin.
“The best way to detect skin cancer early is knowing how to identify the signs and it’s best to see the doctor for rectification,” he said adding that most skin cancers occurred in the trunk or torso or legs.
Skin cancer treatment
Dr Zee said immunotherapy in treating skin cancer had been used decades ago and was said to represent a key breakthrough in the treatment of metastatic MSC.
“Immunotherapy involves the use of medicines to stimulate a patient’s own immune system to recognise and destroy cancer cells more effectively.
“While immunotherapy has been used by doctors for several decades, a new class of immunotherapy medicines, known as immune checkpoint inhibitors, which were put into use in 2010, have been shown, for the first time, to extend the survival for patients with metastatic melanoma.”
An important role of the immune system is its ability to keep itself from attacking healthy cells in the body.
Dr Zee explained: “To do this, it uses ‘checkpoints’ or molecules in immune cells that need to be turned on (or off) to start an immune response. Researchers now recognise that melanoma cells sometimes use these checkpoints to avoid being attacked by the immune system.
“With this in mind, immune checkpoint inhibitors have been designed to target these checkpoints, thereby boosting the response against melanoma cells. Following the success of immunotherapy in melanoma treatment, immune checkpoint inhibitors have been proven to extend survival for patients with lung cancer and kidney cancer.
“Many clinical trials are now being conducted to evaluate their benefits for a variety of other cancers.”
Cancer biomaker
However, Dr Zee said it was known not every patient would respond favourably to such a treatment, adding that another active area of research was the identification of a ‘cancer biomarker’ to help doctors predict which patients are more likely to benefit from this treatment.”
Noting that most NMSCs were discovered at an early stage, he said it was very rare for basal cell carcinoma (BCC), in particular, to spread to another part of the body, and while squamous cell carcinoma (SCC) could sometimes spread, this was usually to nearby lymph nodes.
“Prognosis depends on the type of the skin cancer as well as its size, thickness, locations and sites of spread.
“Most BCCs and SCCs can be successfully treated with surgery to cut out (excise) the cancerous tissue and a surrounding margin of healthy skin, usually under local anaesthetic,” he added.
Dr Zee reiterated that MSC was the most serious type of skin cancer due to its ability to spread early.
“If the cancer is caught at its earliest stage, nine out of 10 patients will still be alive five years later. When MSC has spread to nearby nodes, between five and six out of every 10 patients will still be alive in the same period.
“In cases where MSC has spread (metastasised) to faraway organs like the liver, between two and three out of every 10 patients will be alive five years later,” he said.