Skin Cancer in Singapore – When the Most Visible Cancer Shows Up in Camouflage
Table of Contents
- What is skin cancer?
- Causes and risk factors of skin cancer
- A common myth: People with dark skin are not at risk of skin cancer
- How skin cancer occurs
- Types of skin cancer and their characteristics
- Signs and symptoms of skin cancer
- The diagnosis of skin cancer
- Staging & treatment of skin cancer
- The prognosis of skin cancer
- Skin cancer screening and self-examination
- Preventing skin cancer
- Takeaway message
To many people in Singapore, skin cancer sounds like a problem exclusive to Caucasians. Statistics, however, show that it is not. Ranked as the 6th and 7th most common cancer among Singaporean males and females respectively, skin cancer is not just quite common, it is also on the rise.
Patients with skin cancer I have treated occasionally express disbelief upon receiving the diagnosis. They report noticing skin spots or moles but do not bother having them checked earlier because they did not look obvious or cause any pain. Additionally, it did not cross their mind that these spots could be skin cancer. This has led to delayed diagnosis and less effective treatment in some cases.
This article is written to explain what skin cancer is, the myths and facts about skin cancer, its known causes, common types, diagnosis and treatment. An important part is dedicated to highlighting the importance of self-examination and early detection, how to tell a risky skin spot, and the right way to protect yourself from skin cancer. Now let us start with finding out what skin cancer is.
What is skin cancer?
Skin cancer is the result of one or more genetic mutations that make skin cells go haywire. While the immune system is very effective at identifying cancerous cells and eradicating them, it only takes one surviving cell for cancer to develop. The new skin cancer cells start to multiply in an uncontrolled manner and invade nearby tissues, forming cancerous skin spots.
Worldwide, skin cancer is the most common group of cancer. Over 4,000 new cases of skin cancer are diagnosed every day. Highest incident rates are recorded in countries such as Australia, New Zealand, Norway, Germany, US, Canada. Compared to these countries, Singapore’s incidence rate is relatively lower. However, the proportion of cases diagnosed in advanced stages in our country is known to be higher and the 5-year survival rate is poorer, especially with melanoma.
Causes and risk factors of skin cancer
Like all other malignant tumours, skin cancer develops when DNA mutations alter the cell’s natural growth cycle. While the exact causes of the DNA changes leading to skin cancer are still being studied, scientists have agreed on the following risk factors:
Overexposure to ultraviolet (UV) rays
Research has shown that prolonged exposure to UV light is one of the driving forces of all types of skin cancer. The exposure could stem from being in the sun, using tanning beds, or sun lamps. Despite their various benefits to human’s life, UV rays have potential carcinogenic effects, which is to say, they may cause cancer.
In fact, UV rays from the sun and other sources are a type of radiation. When too much UV radiation hits our skin, the DNA of skin cells might get damaged, requiring repeated repair processes. This increases the risk of a genetic mutation that causes skin cancer.
Having a light skin
People with fairer skin or skin that tends to burn or freckle easily are found to be at higher risk of skin cancer. This is because melanin – the pigment that gives our skin its colour – is a natural protective factor against the harmful effect of UV radiation. The less melanin one has, or the paler one’s skin is, the more damage UV radiation can cause to the skin cell’s DNA.
Having a lot of moles
Moles are not a direct cause of skin cancer. However, having multiple moles that keep popping up may be associated with melanoma.
Family history of skin cancer
Being a relative to someone with skin cancer predisposes you to the disease. This is especially true for melanoma. One study suggests that the reason behind this predisposition is the similar lifestyle. If a family member gets skin cancer because of sunlight exposure, his/her other siblings are likely to be under the same exposure and therefore share the risk.
Personal history of skin cancer
If you developed skin cancer before, there is a risk that cancer will return. In a study involving 969 participants with skin cancer to assess treatment outcomes, scientists found that about 17% of them experienced skin cancer relapse after complete remission. This highlights the importance of frequent self-examination and follow-up among treated skin cancer patients.
Weakened immune system
Any disease or medication that weakens your immune system raises your risk of skin cancer. Factors that suppress the immune system may include:
- Immunosuppressant drugs
- Autoimmune diseases that cause immune dysfunction
Older individuals are at a higher risk of skin cancer. This trend is thought to result from the accumulated effect of UV radiation exposure over the lifetime.
A common myth: People with dark skin are not at risk of skin cancer
Although light skin is a well-established risk factor, it is not true that those with dark skin do not have to worry about skin cancer. The interplay of various risk factors make it impossible to ascertain how more or less likely a particular skin tone is prone to skin cancer compared to another one. Statistics have also shown that people of any ethnicity and skin type can get skin cancer.
The other challenge for people with darker skin tone is that it may make the early signs of skin cancer less visible. They may dismiss a cancerous skin lesion as a normal skin mark. In Singapore, low awareness of the disease could also contribute to the delay in getting symptoms checked by skin cancer specialists. As our country has a high average UV index and sun exposure throughout the year, it is important for everyone to learn how to protect your skin and spot the early signs and symptoms of skin cancer, regardless of your skin colour.
How skin cancer occurs
To understand how skin cancer happens, it is useful to have a basic knowledge of the skin anatomy.
The skin is the largest organ in our body, stretching to about 1.5 – 2 square metres and weighing about 3 – 3.5 kg. It is made up of three layers – the Epidermis, Dermis, and Hypodermis. The epidermis is where the vast majority of skin cancer cases develop from, so we will focus on it below.
The epidermis is the outermost layer of the skin. Its thickness varies throughout the body, ranging from 0.05mm in sensitive areas such as the eyelids to 1.5mm in areas such as the soles of our feet. In this skin layer, we find cells such as keratinocytes, melanocytes, and Merkel cells, among others. When each of these cell types go rogue, we have a different skin cancer type.
Keratinocytes are the main cell types of the epidermis and responsible for producing a protein called keratin. You may learn about keratin as a hair treatment at your hair salon, but the main purpose of keratin is to help waterproof our skin and protect the tissues below it. Among keratinocytes, there are two important types of cell called basal cell and squamous cell.
Basal cells are located deeper in the epidermis and are responsible for skin regeneration. As new basal cells are created, they push up to the skin’s surface. This process flattens and turns them into squamous cells, which constantly shed and replace themselves on the surface of the skin. Both of these cells can occasionally grow out of order, due to the various risk factors we discussed above.
When basal cells become cancerous, the skin cancer type is referred to as basal cell carcinoma (BCC). It is the most common type of skin cancer, making up 50-80% of skin cancers. Squamous cell carcinoma (SCC) occurs when the squamous cells behave out of control, estimated to represent 20-50% of skin cancers.
Melanocytes in the epidermis make melanin, giving our skin, as well as our eyes and hair, their colour. As we learn from the Risk Factors part above, melanin also provides protection for our skin against harmful UV radiation. When they fail to do their jobs and become malignant, it gives rise to a skin cancer type known as melanoma. Melanoma is estimated to account for 1% of skin cancers, which is a good thing since this cancer can be fatal if not discovered early.
Finally, the Merkel cells in the epidermis are a type of neuroendocrine cells, which means they receive and respond to sensations. Cancer of the Merkel cells is known as Merkel cell carcinoma, a very rare yet aggressive type of skin cancer. It is also classified as a type of neuroendocrine tumour (NET), therefore being referred to by other names including neuroendocrine carcinoma of the skin or trabecular cancer. To learn more about NET, check out our dedicated article on neuroendocrine tumour here.
Types of skin cancer and their characteristics
So far, we have learnt that skin cancer is categorised based on the type of skin cell that it develops from. The common types consist of basal cell carcinoma, squamous cell cancer, melanoma, Merkel cell carcinoma.
One more type of skin cancer we have not addressed is called lymphoma of the skin. It is a rare form of skin cancer, with an incidence rate similar to that of Merkel cell carcinoma. Like other types of lymphoma, it develops from lymphocyte cells – a type of white blood cells forming our immune system. Skin lymphoma stems from the lymphocytes present in the skin. It often grows slowly and might not need any treatment rather than active monitoring. We covered lymphoma in our cancer guide here.
You may hear oncologists refer to skin cancers with the word ‘cutaneous’ added in front of their names. ‘Cutaneous’ means ‘skin’ in medicines. Doctors may also use the word ‘carcinoma’ instead of cancer, which means cancer of the skin’s epithelial tissue. As such, cutaneous squamous cell carcinoma and squamous cell cancer refer to the same disease. To better understand words such as ‘carcinoma’ and ‘cutaneous’, please refer to our article on common oncology terms for a rundown.
Below is a summary of the note-worthy characteristics of the 4 common skin cancer types and common areas of the body they can pop up.
Signs and symptoms of skin cancer
Skin cancer is the most visible cancer, typically showing up as new growths on the skin, changes from normal skin or open sores that do not heal well. The trouble is they can look like a normal wart, sore, mole, blemish or even a pimple, normal scar or skin marking. They may or may not be painful. They can be a raised lump or bump or scab on the skin that you can feel with your hand. Other times, they are flat, which makes it difficult to spot yourself if they appear at the back.
Many patients find out about their skin cancer when they visit a dermatologist to have a wart or a completely different skin issue checked. This is why it is important to self-examine to look for any new growths and have them checked by a professional. Pay attention to warts or open sores that do not heal after a week, or heal and then come back; moles that grow quickly; scar-like patches that develop without any injury; or skin bumps that bleed, become swollen or scaly, or feel itchy, painful or tender.
In the majority of cases, they are benign. Only a small number of these skin spots or lumps are atypical, which is to say they are not normal and need to be thoroughly checked by a dermatologist or specialist. However, without noticing the signs and presenting them for a professional examination, there is a chance skin cancer is left undetected and therefore untreated.
Spot the early signs of skin cancer with the ABCDE method
Learning how to differentiate between benign and atypical skin spots is crucial. A patient-friendly guide known as the ABCDE method can be helpful for you to identify an atypical mole or spot. Here is what the letters represent:
[A] Asymmetry – When a mole has asymmetrical sides, it could indicate melanoma.
[B] Border – When the mole is even and smooth, you have nothing to worry about. Uneven edges, however, may be the first sign of melanoma.
[C] Colour – Brown, unicolored moles are generally harmless. When you see a mole with differences in shade, contact your dermatologist.
[D] Diameter – Small moles tend to be benign. Once the diameter of a mole reaches 6 millimetres, things become risky.
[E] Evolving – Rapid changes in the shape, colour, or texture of the mole is a bad sign. Bleeding, itching, and crusting moles should also call for concern.
Up to 80% of melanomas – the most dangerous form of skin cancer – occur in a new lesion. If you notice any of the above signs, contact your doctor as soon as possible to rapidly diagnose your atypical skin growth. Early diagnosis of skin cancer is almost always synonymous with higher survival rate.
The diagnosis of skin cancer
When you visit a doctor to have your symptoms checked, the doctor will first examine the symptomatic spots and your skin with a dermatoscope. The doctor may also discuss with you about your medical history and relevant risk factors.
If skin cancer is suspected, a biopsy will be ordered to confirm the diagnosis, which is known as the gold standard exam to diagnose cancer. It can be done as part of a surgery to remove the entire problematic area, or just to take a sample of the skin. Biopsy results will confirm it is skin cancer, and if so, the type, level of invasion (i.e., how deep cancer has grown into the skin) and the stage of cancer.
In some cases such as advanced melanoma, other tests including imaging tests may follow, to check if cancer has spread to the lymph nodes or other organs. For superficial skin cancers like squamous cell carcinoma or basal cell carcinoma, biopsy to remove the entire lesions is often the only test needed.
Staging & treatment of skin cancer
The basic treatment of skin cancer depends on its type and stage. Generally speaking, treatment for different stages of cancer involves removing the lesions and eliminating cancer cells that may have made their ways out of the original sites.
For stage 0 skin cancer, the cancer is limited to the most superficial layer of the skin, which allows the dermatologist to remove the entire tumour.
Stages 1 and 2 skin cancer can also be removed by a biopsy or a mini-surgical procedure, but the surgeon may remove extra tissue as a security margin.
Stage 3 skin cancer is treated by removing the main tumour as well as the nearby lymph nodes since cancer cells would have spread to them.
Stage 4 skin cancer is more delicate to deal with as the spread of cancer cells is often extended, which mandates the use of other treatments, such as immunotherapy drugs.
With the diagnosis and staging of your cancer, your doctor will recommend one or more of the following therapies to treat skin cancer. Each of these therapeutic approaches has its positive and adverse effects. In the end, it is up to the patient and their physician to discuss the optimal treatment option.
Cryosurgery – Using frozen liquid nitrogen, cryosurgery destroys the cancerous tissues.
Excisional surgery – This procedure involves cutting out the growth and a margin with it.
Mohs surgery – This is a sophisticated procedure that removes the cancer layer by layer. Every layer is then examined under the microscope to see whether abnormal cells are present.
Curettage and electrodesiccation – Using a long blade, your doctor will scrape away the cancer cells.
Chemotherapy – Chemotherapy involves taking cytotoxic drugs to kill cancer cells.
Targeted therapy – Using drugs that target certain proteins associated with cancer cells, this therapy is often recommended for patients with metastatic, high-risk melanoma who carry a specific gene mutation.
Radiation – Energy beams are used to kill cancer cells.
Immunotherapy – These medications work by stimulating your immune system to target the skin cancer cells.
The prognosis of skin cancer
Among skin cancer forms, melanoma and Merkel cell skin cancer are known to have the worst prognosis, especially if detected late. Fortunately, they are also the rare types. Below is a breakdown of the most common skin cancers and their respective prognoses. Do note that available data reported below is from the US. They also do not take into account age, individual’s responses to treatment and other factors. Patients are recommended to take this only as a reference and discuss with your oncologist about your personal outlook.
According to the American Cancer Society, the five-year survival rate of melanoma is 99% if cancer is detected early when it is still localised. However, if melanoma has spread, the rates decrease drastically, to 60% for cancer that has metastasized to the lymph nodes, and 30% if it has made its way to distant organs.
Basal and squamous cell carcinomas
Most basal and squamous cell cancers are not aggressive and can be cured. However, in the rare cases when they metastasize to lymph nodes, it is estimated that less than half of the patients survive for 5 years.
Merkel cell skin cancer
Compared to other skin cancers, Merkel cell cancer has a lower survival rate. The ACS states that the five-year survival rate of Merkel cell skin cancer is 64%.
Skin cancer screening and self-examination
An early diagnosis of skin cancer is indispensable to increase your chances of survival. The good news is that skin cancer is one of the few cancers that are actually visible. In some cases, it is also palpable. If you spend a lot of time in the sun or identify with other risk factors mentioned above, screening and self-examination may save your life.
Screening for skin cancer revolves around a visual examination by the patient themselves or their healthcare provider. If you see a doctor for skin cancer screening, he/she will perform a general body examination, which includes checking your birthmarks, moles, and other pigmented or unusual areas. Your doctor will examine the colour, shape, size, and texture of the lesion discovered. If it is suspicious, further diagnosis steps will be conducted.
You can also self-examine at home, in between screening sessions at the doctor or when you feel necessary. Follow below instructions for self-examination:
- Stand in front of a mirror in a well-lit room and perform a full-body visual examination
- Check out the sun exposed areas on your face and neck
- Check forearms, palms, and underarms
- Inspect your toes and the soles of your feet
- With a hand mirror, examine your back, scalp, and buttocks
- Check the spotted skin growth using ABCDE method. In general, anything that is new, evolving or unusual should not be ignored.
Preventing skin cancer
It is not possible to protect ourselves against all the risk factors of skin cancer. However, we can prevent a major impactful factor – our exposure to UV radiation. Try limiting your exposure to the sun and wear broad-spectrum sunscreen, use sun glasses or cover up whenever you go outside. We also know that indoor tanning using tanning beds and sunlamps is not safe for your skin either, so make sure you avoid these devices.
In limiting exposure to UR rays, you do not have to give up all your favourite outdoor activities or avoid the sun altogether. Some sunlight is beneficial to improve our mood, strengthen our bones, and boost our immunity. The key is to be safe when going under the sun. Below are some useful tips and a reminder of the myths and facts to keep in mind in preventing skin cancer for yourself and loved ones.
Skin cancer is not just a problem of light-skinned people who live elsewhere in the world. It is happening here in Singapore and currently ranks among the top 10 cancers. As more people adopt an active outdoor lifestyle, being complacent about skin cancer will put us at higher risk.
To protect yourself from skin cancer, practise sun safety with sunscreen and shades, equip yourself with knowledge of skin cancer signs and symptoms and conduct regular self-examinations. Do not ignore areas typically hidden from the sun such as the soles of your feet or your palms. Visit doctors or specialists as soon as you notice anything unusual. Detected early, even the most fatal type of skin cancer – melanoma – is highly treatable.
Dr Donald Poon