Mole cancer – malignant melanoma

As the name suggests, this is a malignant condition feared by everyone, not least all of us who enjoy the many important benefits the sun provides.

Mole cancer is a type of cancerous tumour that occurs in the skin’s pigment-producing cells. It is usually associated with fair skin and overexposure to UV rays.

The incidence of malignant melanomas in Norway is among the highest in the world, and rising. Each year, around 1500 people are diagnosed with the condition in Norway.

Mole cancer is the second commonest form of cancer in people aged 15-54, but is now increasing most rapidly among the over-60s. This form of cancer is twice as common in Southern as in Northern Norway.

In women, mole cancer was previously most often seen on the legs, while now it is usually on the back and upper body in both men and women.

Risk factors
The biggest known risk factor for developing mole cancer is fair skin together with overexposure to UV rays. The risk increases with the number of incidents of sunburn.
There is a particular correlation between a high number of incidents of sunburn in childhood and developing mole cancer as an adult.

UV rays can damage the genetic material in the pigment cells, which in later life may cause the cells to start to divide and grow in an uncontrolled manner.

It is important to be aware that mole cancer does not necessarily develop on the areas of the body that have been most exposed to the sun.

Stages 0-4
Mole cancer is divided into stages from 0 to 4 based on how deep the mole is sitting in the skin, whether the cancer cells have spread to the lymphatic system and whether the cancer has spread to other organs.

The earliest stages offer a good prognosis, while Stage 4, which means the cancer has spread to other organs, is very serious and may have a poor prognosis.

Pigment-producing cells are also found in mucous membranes (mouth, nose, intestinal wall, vagina) and the eyes, which means that malignant melanoma can also manifest here, but is then called something different.

Symptoms


Mole cancer can occur in existing moles or in new ones.

The ABCDE method is a useful mnemonic to remember the symptoms of mole cancer:
A stands for Asymmetry, which means that the mole is not uniform in appearance, i.e. the one half of the mole is not a mirror image of the other.
B stands for Border, as malign moles often have irregular edges.
C stands for Colour. Malignant moles may change colour, often becoming dark blue or black.
D stands for Diameter, as malignant moles often increase in size.
E stands for Evolving, as any mole that changes appearance should be investigated. Mole cancer should also be suspected in the case of moles that itch, sting or bleed.
If mole cancer takes the form of a new mole, this will often grow quickly and look different from the other moles.

Treatment and prevention
Treatment of mole cancer involves removing all suspicious moles with a few millimetres’ margin of normal skin, and examining these under a microscope. If mole cancer is confirmed, more of the skin around and beneath the mole must be removed.

The lymph nodes that drain the area must also be checked, as this could reveal whether the cancer has spread. Further treatment involves radio- and chemotherapy.

People with a family history of mole cancer and people with large moles (larger than 2 cm) should be examined regularly by a dermatologist. Sunbeds should be avoided by young people under 18, and particularly by people with fair skin, red hair, freckles, a large number of moles or a family history of mole cancer.

When sunbathing, you should avoid intensive periods in the sun and use a sunscreen with a minimum SPF of 15 that provides protection against both UVA and UVB rays. Sunscreen does not provide complete protection against UV rays, and you should avoid sunbathing in the middle of the day when the sun is strongest.

New moles in people over 40 should always be investigated.

Examination and diagnosis
Mole cancer is diagnosed by removing suspicious moles and examining them under a microscope. Moles can be inspected carefully in good light or using a dermatoscope (a type of magnifying glass to examine the skin).

Suspicious moles can be removed by a GP/family doctor. If mole cancer is confirmed, it is important to check whether it has spread.

This is usually done by means of an ultrasound examination of the liver and the lymph nodes that drain the area where the mole cancer is located. An X-ray of the lungs is also taken.

Cause
Mole cancer is usually associated with fair skin types and overexposure to UV rays. There is a high correlation between number of incidents of sunburn, particularly in childhood and adolescence, and developing mole cancer. People with fair skin types that go red and not brown in the sun, and people with red hair and freckles are particularly vulnerable. People with a large number of moles, large moles or a family history of mole cancer should also be checked regularly. Frequent use of sunbeds is believed to increase the risk. If you have had mole cancer previously, you will have a greater risk of getting it again.

Prognosis
The prognosis depends on how deep the cancerous mole is sitting in the skin and whether the cancer has already spread when it is diagnosed.

Mole cancer is divided into Stages 0-4. The stages are determined based on the depth of the mole in the skin, whether the cancer cells have spread to the lymphatic system and whether the cancer has spread to other organs.

Stage 0 offers the best prognosis, and Stage 4 the worst.

There is a good prognosis for mole cancer that is detected early and before it has spread, with a five-year survival rate of 90%. 80% of patients will be cured if the mole is removed.

An increasing number of people are being diagnosed with mole cancer and undergoing treatment. If you have been diagnosed with mole cancer previously, you have a greater risk of getting it again later in life and should therefore be monitored carefully.

Recent years have brought major improvements in treatment. The correct surgical primary treatment cures 80-90% of cases, while 10-20% of patients experience a relapse.

Treatment for metastatic malignant melanoma has changed significantly in the last 1-2 years, based on clinical experience with new drugs.

Facts about mole cancer (malignant melanoma)

  • Mole cancer is a type of cancerous tumour that occurs in pigment-producing cells (melanocytes) in the epidermis.
  • It may occur in existing moles or in new ones.
  • Mole cancer is usually associated with fair skin and overexposure to UV rays.
  • Mole cancer can occur anywhere on the body but is commonest on the back and upper body in both men and women.
  • Moles that change appearance and new moles should be examined by a doctor, and possibly removed.