Skin cancer means the uncontrollable growth of abnormal cells in the epidermis caused by unrepaired DNA damage which triggers mutations. Epidermis is the outermost layer of the skin. The mutations lead the skin cells to grow rapidly and form malignant tumors. It mostly develops on skin exposed to the sun. It primarily forms on areas, including the face, scalp, lips, neck, ears, arms, chest and hands, and on the legs in women. However, skin cancer can also form on areas of the skin not ordinarily exposed to sunlight. It affects human beings of all skin tones, including those with darker complexions.
As per report, skin cancer in India accounts for less than 1 per cent of all the cancers.
Types of skin cancer
There are three major types of skin cancer:
- Squamous cell carcinoma (SCC) – It means an uncontrolled growth of abnormal cells forming from the squamous cells in the outmost layer of skin – epidermis. They are common on sun-exposed areas, including the face, scalp, hands, ears and neck, where the skin often reveals signs of sun damage, including age spots and wrinkles. Cumulative, long-term exposure to UV radiation from the tanning beds and sun result in most SCCs.
SSC is the most common type of skin cancer. It can sometimes grow rapidly and metastasize if not detected and treated in the beginning.
- Basal cell carcinomas (BCCs) – BCCs are abnormal, uncontrolled growths that form from the skin’s basal cells in the outermost layer of skin – epidermis. They mostly develop on skin areas typically exposed to the sun, such as the neck, ears, face, scalp, shoulders and back. Most of these cancers are formed by the combination of intermittent, intense exposure and cumulative, long-term exposure to UV radiations from the sun.
BCCs can be destructive locally if not detected and treated early. Sometimes these cancers metastasize; and in very rare instances they can be fatal.
- Melanoma – It is a cancer which develops from melanocytes, the skin cells that produce melanin pigment, which gives skin its color. They often resemble moles and sometimes may grow from them. They can be found on any area of the body, even in areas that are not exposed to the sun.
Melanoma is mostly triggered by the kind of intense, intermittent sun exposure that leads to sunburn. Use of tanning bed also increases the risk. It is the most dangerous of the three most major forms of skin cancer. They can be curable when detected and treated early.
Most BCCs have few, if any, symptoms. SCCs may be painful. However, both forms of skin cancer may appear as a sore that crusts, bleeds, oozes, or otherwise will not heal. They start as a slowly growing bump on the skin that may bleed after minor accident.
Signs and symptoms of BCCs include:
- Appearance of a shiny red, pink, pearly, or translucent bump
- Raised reddish patch of skin that may itch or crust, but is usually not painful
- A yellow, white, or waxy area with a poorly defined border that may resemble a scar
- Pink skin growths or lesions with raised borders which are crusted in the center
Signs and symptoms of SCCs include:
- A wart-like growth
- Persistent, scaly red patches with irregular borders which may bleed easily
- Open sore that does not go away for weeks
- A raised growth with a rough surface that is indented in the middle
Actinic keratoses (AK), also known as solar keratoses, are crusty, scaly lesions caused by damage from ultraviolet light, often in the scalp, facial area, and back of the hands. They are considered pre-cancers because if untreated, up to 10 per cent of actinic keratoses may develop into squamous cell carcinomas.
Melanoma signs include:
- A mole that changes in size, color or feel, or that bleeds
- A large brownish spot with darker speckles
- A tiny lesion with an irregular border and portions that appear blue, red, pink, white or blue-black
- A painful lesion that burns or itches
- Dark lesions on the soles, palms, fingertips or toes, or on mucous membranes lining the mouth, vagina, nose or anus
Causes and diagnosis
Much of the damage to DNA in skin cells forms from the ultraviolet radiation found in sunlight and in the lights used in tanning beds. However, sun exposure does not explain skin cancers that develop on skin not typically exposed to sunlight. This means that other factors may contribute to the risk of skin cancer, such as having a condition that weakens the immune system or being exposed to toxic substances.
There are various ways to diagnose skin cancer:
- Examine the skin – The doctor may look at the skin to determine whether the skin changes are likely to be skin cancer.
- Skin biopsy – The doctor may remove the suspicious-looking skin for lab testing. A biopsy can determine whether it is skin cancer and, if so, what type of skin cancer it is.
In case the doctor determines you have skin cancer, you may have additional tests to determine the stage of the cancer. Some of these tests might include imaging tests to examine the nearby lymph nodes for signs of skin cancer, or a treatment to remove a nearby lymph node and analyze it for signs of cancer, known as sentinel lymph node biopsy.
Stages and treatment options
Staging usually is not needed for basal cell skin cancer. It is because these cancers are often treated before they spread to other parts.
Squamous cell skin cancers have a higher probability of metastasizing, although the risk is still fairly low.
These cancers are staged as follows:
- Stage 0 – The cancerous cells are only present in the epidermis and have not spread deeper into the skin.
- Stage 1 – The tumor is 2 cm or less and has not spread to the nearby lymph nodes.
- Stage 2 – The tumor is 2 to 4 cm and has not spread to the nearby lymph nodes.
- Stage 3 – The tumor is more than 4 cm; or it has spread to one of the following:
- Bone, where it has caused minor damage
- A nearby lymph node
- Subcutaneous tissue, which is the deepest, innermost layer of skin that includes nerve endings, blood vessels, and hair follicles
- Stage 4: The tumor can be of any size and has spread to:
- Bone marrow or bone
- Other organs in the body
- One or more lymph nodes, which are larger than 3 cm
Staging of melanoma skin cancer is as below:
- Stage 0 – The cancer is only present in the epidermis.
- Stage 1 – The cancer is up to 2 mm thick. It has not yet spread to the lymph nodes or other areas, and it may or may not be ulcerated.
- Stage 2 – The cancer is at least 1 mm thick but might be thicker than 4 mm. It has not yet spread to the lymph nodes or other areas, and it may or may not be ulcerated.
- Stage 3: The cancer has spread to one or more lymph nodes or nearby lymphatic channels but not distant areas. The original cancer may no longer be visible. If it is visible, it may be ulcerated and also thicker than 4 mm.
- Stage 4 – The cancer has spread to the distant lymph nodes or sites, such as the lungs, brain, or liver.
Small skin cancers limited to the surface of the skin may not require treatment beyond an initial skin biopsy which removes the entire growth. In case additional treatment is needed, options may include:
- Excisional surgery – This treatment may be appropriate for any type of skin cancer. The doctor cuts the cancerous tissue and a surrounding margin of healthy skin. A wide excision (removing extra normal skin around the tumor) may also be recommended in few cases.
- Freezing – The doctor may destroy actinic keratoses and some small, early skin cancers by freezing them with liquid nitrogen. The dead tissue sloughs off when it thaws.
- Mohs surgery- This procedure is for recurring, larger, or difficult-to-treat skin cancers, which may include both squamous and basal cell carcinomas. It is mostly used in areas where it is necessary to protect as much skin as possible, such as on the nose. During the surgery, the doctor removes the skin growth layer by layer, analyzing each layer under the microscope, until no abnormal cells remain.
- Cryotherapy or curettage and electrodesiccation – After removing most of the growth, the doctor scrapes away layers of cancer cells using a device with a circular blade. An electric needle destroys the remaining cancer cells. This procedure may be used to treat squamous cell cancers or basal cell cancers.
- Radiation therapy – It uses high-powered energy beams such as protons or x-rays to kill cancer cells.
- Chemotherapy – Drugs are used to kill cancer cells. Systemic chemotherapy can also be used to treat skin cancers which have spread elsewhere in the body.
- Photodynamic therapy – The treatment destroys skin cancer cells with a combination of drugs and laser light and that makes cancer cells sensitive to light.
- Biological therapy – It uses the body’s immune system to kill cancer cells.
Side effects of treatment
Side effects of skin cancer treatments may include:
- Skin irritation, ranging from blistering to redness and peeling
- Changes in skin color
- Damage to teeth and saliva-making glands when treating cancers near these structures
- Hair loss in the area being treated
- Tiredness or fatigue
- Joint pain
- Bone thinning
Survivorship and prevention for skin cancer
Completing skin cancer treatment can be both exciting and stressful. Along with the risk of the melanoma coming back, people who have had it have a high risk of developing another one, hence it is very important to keep all follow-up appointments. The schedule should include regular lymph node and skin exams by yourself and by the doctor. In addition, imaging tests such as CT scans or ultrasound may be recommended for some people.
Be sure to follow the measures below to reduce the risk of developing skin cancer:
- Use sunscreen that has an SPF of 15 or higher, as well as UVA and UVB protection. Remember to reapply every two hours.
- Avoid using indoor tanning beds. Instead, use a self-tanning product.
- Try and stay in the shade during the hottest hours of the day. The sun is usually the strongest between 10 – 4 pm.
- Wear clothes that protects the skin. This includes clothing that covers most of the legs and arms, hats with a wide brim, and shades that wrap around.
- Be aware of the surroundings. Water, snow, and sand can all reflect light from the sun. This can increase the chance of getting a sunburn.
- Check your skin regularly. In case you see a suspicious-looking mole or mark, make an appointment with a dermatologist. In addition, make a yearly appointment with the dermatologist for a skin exam.