Skin cancer is the most common form of cancer. The two most common types are basal cell cancer and squamous cell cancer.
They usually form on the head, face, neck, hands and arms. Another type of skin cancer, melanoma, is more dangerous but less common.
Anyone can get skin cancer, but it is more common in people who:
- Spend a lot of time in the sun or have been sunburned
- Have light-coloured skin, hair and eyes
- Have a family member with skin cancer
- Are over 50
Treatment works better when cancer is found early. If not treated, some types of skin cancer cells can spread to other tissues and organs.
How skin cancer starts
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body. Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumour. Not all tumours are cancer.
Tumours can be benign or malignant:
Benign tumoursare not cancer: they are rarely life-threatening. Usually, benign tumours can be removed, and they seldom grow back. Cells from benign tumours do not spread to tissues around them or to other parts of the body.
Malignant tumoursare cancer: they are generally more serious and may be life-threatening. Malignant tumours usually can be removed, but they can grow back. Cells from malignant tumours can invade and damage nearby tissues and organs.
Also, cancer cells can break away from a malignant tumour and enter the bloodstream or lymphatic system. That is how cancer cells spread from the original cancer (the primary tumour) to form new tumours in other organs. The spread of cancer is called metastasis. Different types of cancer tend to spread to different parts of the body.
Types of skin cancer
Exposure to sunlight can increase your risk of developing one or more of the three types of skin cancer. The types include basal cell carcinoma, squamous cell carcinoma and melanoma.
Basal cell carcinoma
- Basal cell cancer, also called rodent ulcer, is caused by exposure to the sun.
- There are five clinical types - nodulo-ulcerative, superficial, pigmented, morpheaform and keratotic.
- The most common form - nodulo-ulcerative - consists of a raised, round lesion with small blood vessels concentrated around it and often a central ulcer.
- Treatment is by scraping the tumour out, full surgical excision, sometimes X-ray treatment or imiquimod (aldara).
- After incomplete removal, basal cell cancer can recur in the same place up to 10 years after treatment.
- Sun exposure is the single most important cause of this skin cancer.
- However, basal cell cancer can also arise in areas of skin with chronic scarring or X-ray damage.
Squamous cell carcinoma
- Squamous cell carcinoma is easy to cure, provided it is diagnosed at an early stage.
- If not diagnosed early, it tends to spread to the lymphatic system and other tissue cells, requiring the removal of lymph glands.
- About 5 - 10 percent of all skin cancers are melanoma.
- It is a very aggressive type of cancer.
- It can spread to other tissue cells at an early stage.
- The chances of recovery depend on how deeply the lesion has penetrated the skin. In cases where the penetration is less than 0,75mm, the chance of recovery is about 100 percent. With a lesion deeper than 4mm, the chance of surviving ten years or longer is less than 15 percent.
Risks for skin cancer
Doctors cannot explain why one person develops skin cancer and another does not. However, we do know that skin cancer is not contagious. You cannot 'catch' it from another person.
Research has shown that people with certain risk factors are more likely than others to develop skin cancer. A risk factor is something that may increase the chance of developing a disease.
Studies have found the following risk factors for skin cancer:
- Ultraviolet (UV) radiation: UV radiation comes from the sun, sunlamps, tanning beds, or tanning booths. A person's risk of skin cancer is related to lifetime exposure to UV radiation. Most skin cancer appears after age 50, but the sun damages the skin from an early age. UV radiation affects everyone. But people who have fair skin that freckles or burns easily are at greater risk. These people often also have red or blonde hair and light-coloured eyes. But even people who tan easily can get skin cancer. UV radiation is present even in cold weather or on a cloudy day.
- Scars or burns on the skin
- Infection with certain human papillomaviruses
- Exposure to arsenic at work
- Chronic skin inflammation or skin ulcers
- Diseases that make the skin sensitive to the sun, such as xeroderma pigmentosum, albinism, and basal cell nevus syndrome
- Radiation therapy
- Medical conditions or drugs that suppress the immune system
- Personal history of one or more skin cancers
- Family history of skin cancer
- Actinic keratosis: a ctinic keratosis is a type of flat, scaly growth on the skin. It is most often found on areas exposed to the sun, especially the face and the backs of the hands. The growths may appear as rough red or brown patches on the skin. They may also appear as cracking or peeling of the lower lip that does not heal. Without treatment, a small number of these scaly growths may turn into squamous cell cancer.
- Bowen's disease: Bowen's disease is a type of scaly or thickened patch on the skin. It may turn into squamous cell skin cancer.
If you think you may be at risk for skin cancer, you should discuss this concern with your doctor. Your doctor may be able to suggest ways to reduce your risk and can plan a schedule for checkups.
A change on the skin is the most common sign of skin cancer. This may be a new growth, a sore that doesn't heal, or a change in an old growth.
Skin changes to watch for:
- Small, smooth, shiny, pale, or waxy lump
- Firm, red lump
- Sore or lump that bleeds or develops a crust or a scab
- Flat red spot that is rough, dry, or scaly and may become itchy or tender
- Red or brown patch that is rough and scaly
If you have a change on the skin, your doctor must find out whether it's due to cancer or to some other cause.
Your doctor will remove all or part of the area that doesn't look normal. The sample goes to a lab, where a pathologist checks the sample under a microscope. This is called a biopsy - the only sure way to diagnose skin cancer.
You may have the biopsy in a doctor's office or as an outpatient in a clinic or hospital. Where it's done depends on the size and place of the abnormal area on your skin. You probably will have local anaesthesia.
There are four common types of skin biopsies:
- Punch biopsy: The doctor uses a sharp, hollow tool to remove a circle of tissue from the abnormal area.
- Incisional biopsy: The doctor uses a scalpel to remove part of the growth.
- Excisional biopsy: The doctor uses a scalpel to remove the entire growth and some tissue around it.
- Shave biopsy: The doctor uses a thin, sharp blade to shave off the abnormal growth.
You may want to ask your doctor these questions before having a biopsy:
- Which type of biopsy do you recommend for me?
- How will the biopsy be done?
- Will I have to go to the hospital?
- How long will it take? Will I be awake? Will it hurt?
- Are there any risks? What are the chances of infection or bleeding after the biopsy?
- What will my scar look like?
- How soon will I know the results? Who will explain them to me?
Are you at risk of skin cancer? Then your doctor may recommend that you do a regular skin self-examination.
If he/she has taken photos of your skin, comparing your skin to the photos can help you check for changes.
The best time to do a skin self-examination is after a shower or bath. You should check your skin in a well-lighted room using a full-length mirror and a hand-held mirror. It's best to begin by learning where your birthmarks, moles, and blemishes are and what they usually look and feel like.
Check for anything new:
- A new mole (that looks abnormal)
- A change in the size, shape, colour or texture of a mole
- A sore that does not heal
Check yourself from head to toe. Don't forget to check all areas of the skin, including the back, the scalp, between the buttocks, and the genital area:
- Look at your face, neck, ears and scalp. You may want to use a comb or a blow dryer to move your hair so that you can see better. You also may want to have a relative or friend check through your hair because this is difficult to do yourself.
- Look at the front and back of your body in the mirror, then raise your arms and look at your left and right sides.
- Bend your elbows and look carefully at your fingernails, palms, forearms (including the undersides) and upper arms.
- Examine the back, front and sides of your legs. Also look between your buttocks and around your genital area.
- Sit and closely examine your feet, including the toenails, the soles, and the spaces between the toes.
By checking your skin regularly, you will become familiar with what is normal for you. It may be helpful to record the dates of your skin examinations and to write notes about the way your skin looks. If you find anything unusual, see your doctor right away.
There's no getting away from it. You need to cover up when you go outside, even when it's cloudy. Here's what else you should know:
- The sun has two types of rays - those you can see, and ultraviolet (UV) rays, which can cause skin cancer. These are the rays you need to avoid now in order to reduce your chances of getting skin cancer at a later stage in your life.
- Stay out of the sun and this will solve the problem. But doing this is not so simple. Everyone has to go outdoors on a regular basis. Remember that the UV rays are much stronger in the summer, close to the equator or in high-lying areas.
- Plan outdoor activities for before 10h00 and after 16h00 when the UV rays are much weaker.
- Remember that UV rays can burn you right through the fabric of beach umbrellas and that they can reflect off water, sand and cement.
- Think when you dress. You might look great in that short-sleeved top, but keep it for when you go out in the evening. Wear long sleeves and cover as much of your body as possible. Remember that thin white cotton and wet clothing give no protection at all against UV-rays.
- Wear a hat. A proper hat with a wide brim. A peak cap, even though it is better than nothing, either protects your face, or your neck - not both. And necks can be so sore when they've been sunburnt. Almost as sore as burnt feet.
- Wear a pair of sunglasses. Not one of those cheap plastic numbers you buy on street corners, but one from a reputable manufacturer, that blocks out UV rays. Ask your pharmacist for more information about this.
- Apply lots of sunblock regularly. Put it on about 20 minutes before you go out into the sun, and even when it is overcast. Use one that is water-resistant, otherwise it will wash off when you go for a swim. Reapply the sunblock at least every hour and a half. Anything with a sun protection factor (SPF) of under 30 is basically a waste of money. The SPF indicates how much longer you can stay in the sun than when you have used no sunblock at all. SPF 30 - 45 blocks out more than 96% of the sun's ultraviolet rays. When you buy sunblock, check that it protects against both UVA and UVB rays.
- Stay away from sun lamps and sun beds - they often emit more UV rays than normal sunlight.