The warning signs of skin cancer

Like many cancers, skin cancers – including melanoma, basal cell carcinoma and squamous cell carcinoma – start as precancerous lesions. These precancerous lesions are changes in skin that are not cancer but could become cancer over time. The NHS says skin cancer affects more than 100,000 people in the UK each year. Learn to spot the early warning signs. Skin cancer can be cured if it's found and treated early.

Actinic keratosis (solar keratosis)

The small, scaly patches caused by too much sun exposure commonly occur on the head, neck, or hands, but can be found elsewhere. They're the early beginnings of skin cancer. Actinic keratosis usually appears on people after the age of 40, but they can show up in much younger people. Fair-skinned, blonde or red-haired people with blue or green eyes are most at risk. Early treatment is advised to stop progression to squamous cell skin cancer.

Actinic cheilitis

Related to actinic keratosis, actinic cheilitis is a precancerous condition that usually appears on the lower lips. Scaly patches or persistent dryness and cracking of the lips may be present. Less common symptoms include swelling of the lip, loss of the sharp border between the lip and skin, and prominent lip lines. Actinic cheilitis may evolve into invasive squamous cell carcinoma if not treated.

Cutaneous horns

The cutaneous horn appears as a funnel-shaped growth that extends from a red base on the skin. It is composed of compacted keratin (the same protein in nails). The size and shape of the growth can vary considerably, but most are a few millimetres in length. Squamous cell carcinoma is often found at the base. It usually occurs in fair-skinned elderly adults with a history of significant sun exposure.

When is a mole a problem?

A mole (naevus) is a benign growth on the skin. While very few moles become cancer, abnormal or atypical moles can develop into melanoma over time. 'Normal' moles can appear flat or raised or may begin flat and become raised over time. The surface is typically smooth. Normal moles are round or oval and no larger than a pencil rubber. Most moles develop in youth or young adulthood. It's unusual to acquire a mole in middle age and beyond.

Dysplastic naevi (atypical moles)

Atypical moles are not cancer, but they can become cancer. They can be found in sun-exposed or sun-protected areas of the body. Atypical moles are larger (6mm or a quarter of an inch across or larger) and more irregular in shape, with notched or fading borders. They may be flat or raised or the surface smooth or rough. They are typically of mixed colour, including pink, red, tan and brown.

Know your ABCDEs

Most moles on a person's body look similar to one another. A mole or freckle that looks different from the others or that has a diameter larger than a pencil rubber or any characteristics of the ABCDEs of melanoma should be checked by a doctor. It could be cancerous. The ABCDEs are important characteristics to consider when examining your moles or other skin growths. You can learn about them in the slides to come.

Know your ABCDEs: 'A' is for asymmetry

Asymmetry means one half of a mole does not match the other half. Normal moles are symmetrical. When checking your moles or freckles, draw an imaginary line through the middle and compare the two halves. If they do not look the same on both sides, ask your doctor to check it.

Know your ABCDEs: 'B' is for border

If the border or edges of the mole are ragged, blurred or irregular, ask your doctor to check it. Melanoma lesions often have uneven borders.

Know your ABCDEs: 'C' is for colour

A mole that does not have the same colour throughout or has shades of tan, brown, black, blue, white or red is suspicious. Normal moles are usually a single shade of colour. A mole of many shades or that has lightened or darkened should be checked by a doctor.

Know your ABCDEs: 'D' is for diameter

A mole is suspicious if the diameter is larger than the rubber on the end of a pencil. Benign moles are usually less than 6 mm (a quarter of an inch) in diameter.

Know your ABCDEs: 'E' is for elevation

If a portion of the mole appears elevated or raised from the skin, ask your doctor to look at it. Melanoma lesions often grow in size or change in height rapidly. A mole that is evolving – shrinking, growing larger, changing colour, begins to itch or bleed – should also be checked.

Tips for screening moles for cancer

Examine your skin after a shower while the skin is wet. A common location for melanoma in men is on the back, and in women, the lower leg. But check your entire body for moles or suspicious spots. The NHS suggests doing this once every couple of months. Start at your head and work your way down. Check the 'hidden' areas: between fingers and toes, the groin, soles of the feet, the backs of the knees. Check your scalp and neck for moles. Use a handheld mirror or ask a family member to help you look at these areas. You should be especially suspicious of a new mole. Take a photo of moles and date it to help you monitor them for change. Pay special attention to moles if you're a teenager, pregnant or going through the menopause – times when your hormones may be surging.

How are moles evaluated?

If you find a mole or spot that has any ABCDEs of melanoma – or one that's tender, itching, oozing, scaly, doesn't heal or has redness or swelling beyond the mole – see a doctor. Your doctor may want to get a tissue sample from the mole and order a biopsy. If found to be cancerous, the entire mole and a rim of normal skin round it will be removed and the wound closed with stitches. Additional treatment may be needed.

An introduction to skin cancer

Malignant melanoma, especially in the later stages, is serious and treatment is difficult. Early diagnosis and treatment can increase the survival rate. Nonmelanoma skin cancers include basal cell carcinoma and squamous cell carcinoma. Both are common and are almost always cured when found early and treated. People who've had skin cancer once are at risk of getting it again; they should have a checkup at least once a year.

Melanoma

Melanoma is not as common as other types of skin cancer, but it's the most serious and potentially deadly.

Squamous cell carcinoma

This nonmelanoma skin cancer may appear as a firm red nodule, a scaly growth that bleeds or develops a crust, or a sore that doesn't heal. It most often occurs on the nose, forehead, ears, lower lip, hands and other areas of the body exposed to the sun. Squamous cell carcinoma is curable if caught and treated early. If the skin cancer becomes more advanced, treatment will depend on the stage of cancer.

Bowen's disease

Bowen disease is also called squamous cell carcinoma 'in situ.' It is a type of skin cancer that spreads outwards on the surface of the skin. By contrast, 'invasive' squamous cell carcinomas can grow inwards and spread to the interior of the body. Bowen's disease looks like scaly, reddish patches that may be crusted; it may be mistaken for rashes, eczema, fungus or psoriasis.

Basal cell carcinoma

Basal cell carcinoma is the most common and easiest to treat skin cancer. Because basal cell carcinoma spreads slowly, it occurs mostly in adults. Basal cell tumours can take on many forms, including a pearly white or waxy bump, often with visible blood vessels, on the ears, neck or face. Tumours can also appear as a flat, scaly, flesh-coloured or brown patch on the back or chest, or more rarely, a white, waxy scar.

Less common skin cancers

Uncommon types of skin cancer include Kaposi's sarcoma, mainly seen in people with weakened immune systems; Merkel cell carcinoma, which is usually found on sun-exposed areas on the head, neck, arms or legs but often spreads to other parts of the body; and sebaceous gland carcinoma, an aggressive cancer originating in the oil glands in the skin.

Who gets skin cancer, and why?

Sun exposure is the biggest cause of skin cancer. But it doesn't explain skin cancers that develop on skin that isn't usually exposed to sunlight. Exposure to environmental hazards, radiation treatment and even heredity may play a role. Although anyone can get skin cancer, the risk is greatest for people who have:

• Fair skin or light-coloured eyes
• An abundance of large and irregularly-shaped moles
• A family history of skin cancer
• A history of excessive sun exposure or blistering sunburns
• Lived at high altitudes or with year-round sunshine
• Received radiation treatments

Reduce your risk of skin cancer

Limit your exposure to the sun's ultraviolet rays, especially between 10 am and 4 pm, when the sun's rays are strongest. Apply sunscreen liberally before going outside (don't forget the lips and ears!), wear a hat and sunglasses and cover up with clothing. And remember, if you notice changes to your skin such as a new growth, a mole changing appearance, or a sore that won't heal, see your doctor straight away.

More reading on skin problems

• What are the symptoms of melanoma?
• Sun exposure and skin cancer
• Sunburn and other sun reactions of the skin
• Sun safety tips
• Psoriasis: What is it?
• Understanding eczema