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Improving early detection of melanoma

Veronique Bataille MD PhD FCRP Consultant dermatologist West Herts NHS Trust

In this article, Dr Veronique Bataille discusses the importance of detecting skin cancer early. She discusses the different types of melanoma, the associated risk factors, the patients at highest risk, as well as melanoma treatment.

Identifying the different types of melanoma

Melanoma has a variety of clinical presentations with different histological features. This is important to recognise as it may affect prognosis as well as management.

Superficial spreading melanoma: The most common form is the superficial spreading melanoma (SSM) which in its early stages will be a flat lesion often originating from a flat junctional mole. Once SSM progresses it can develop raised areas which often imply a poorer prognosis.
Nodular melanoma: In nodular melanoma, the lesion may present as a very small black nodule growing over weeks or months. These lesions are usually more aggressive.
Lentigo maligna: Lentigo maligna are melanoma seen in older subjects on chronically sun exposed sites, usually the face. They often originate from a longstanding pre-existing melanoma that slowly becomes darker and larger. There are two forms of lentigo maligna:
- those without invasion in the dermis which have an excellent prognosis
- those with invasion of atypical melanocytes spreading in the dermis

These lesions are regarded as more dangerous and require more aggressive treatment.

Identifying skin cancer in unusual sites, non-Caucasians, women and children

Melanoma can also appear on the palms and soles or under the nail and may cause diagnostic problems. These lesions are often diagnosed very late and have a poorer prognosis.

Melanoma is extremely rare in non-Caucasians and, when it does occur, affects the non-pigmented palms and soles but not the pigmented part of the skin.

Women are more likely to develop melanoma on the legs while men are more likely to have melanoma on the trunk. It is extremely rare in children as melanoma risk increases with age.

Melanoma cancer rates

Relative to other cancers, melanoma is the most common cancer between the ages of 20 and 35 in Caucasians but it should be remembered that the incidence of melanoma is still very low in that age group. Common cancers such as breast, lung and colon, for example, are around ten times more common than melanoma.

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Atypical moles are an indicator of melanoma risk

Figure 1 - atypical mole syndrome

High-risk groups for skin cancer

Subjects with fair skin and hair are at increased risk of melanoma but the magnitude of the risk is only two-fold. Excessive sun exposure, especially in childhood, may be a risk factor for melanoma. The relationship between melanoma and sunshine is very complex and not dose dependent.

Atypical moles are an indicator of melanoma risk

The most consistent risk factor for melanoma in Caucasians is the number of moles especially atypical moles. The atypical mole syndrome is defined as the presence of more than 100 moles with two or more atypical moles and/or moles on unusual sites such as the breasts in women, buttocks, feet and scalp, see figure 1. The presence of more than 100 moles with atypical moles can increase the risk of melanoma by five- to ten-fold.

Atypical moles are defined as lesions ≥5 mm in diameter with hazy borders and often irregular pigmentation, see figure 2. These lesions, however, should be regarded as a marker of risk, although most atypical moles will never progress to melanoma.

Figure 2 - atypical naevi on the trunk

The importance of family history in determining the risk of skin cancer

Family history is also crucial in determining melanoma risk. There is a two-fold increase in risk in subjects with a relative with cancerous melanoma but this risk may change significantly with age.

In the presence of the atypical mole syndrome and a positive family history, the risk is further increased and these patients should be followed up by a dermatologist. The risk of melanoma increases with the number of melanoma cases in the family and high-risk families should be referred to a cancer genetic clinic for counselling.

There are however, different skin characteristics associated with melanoma and some melanoma patients have no excess of moles. These subjects are usually very fair with freckles and may have sun damaged skin.

A family history of other cancers is also important, particularly pancreatic cancer, brain tumours and breast cancer.

Risk factors for lentigo maligna differ as genetic factors are not as important and chronic sun exposure is more relevant.

What causes melanoma?

As with all cancers, melanoma is likely to be caused by complex interactions between genes and the environment.

Confirming the skin cancer diagnoses

The diagnosis of melanoma can only be confirmed with a full excision biopsy. This will allow the pathologist to perform a full pathological assessment of the lesion.

Referral to a melanoma specialist

All suspicious pigmented lesions should be referred to a dermatologist or plastic surgeon within two weeks. Some GPs with a special interest may deal with skin cancers but need the right level of accreditation. Patients with non-pigmented lesions that are regarded as suspicious or with a family history of melanoma and/or an excess of cancers in the family should be referred for less urgent treatment.

Treatment of melanoma

In all cases the melanoma should be fully removed. In most instances this will involve a simple excision. Most patients will not need any further treatment and will be followed up to check for possible recurrence. More than 80% of melanoma patients have surgery alone and survive their disease with no other treatments. Women tend to survive melanoma better than men.

Unfortunately, there is no successful drug therapy for melanoma. In the palliative setting, there are many chemotherapy regimens which can reduce the bulk of the disease but do not appear to prolong long-term survival. Targeted therapy, which depends on the genetic profile of the tumour, is the way forward for melanoma treatment in the future.

Profile of the author

Dr Veronique Bataille MD PhD FRCP provides treatment for all skin conditions, including those in children. She specialises in the treatment of melanoma, other types of skin cancer, atypical mole syndrome, and family cancer syndromes associated with melanoma. Dr Bataille practises at Princess Grace Hospital, London and West Hertfordshire NHS Trust hospitals where she carries out regular dermatological procedures such as excision and curettage of skin cancers as well as diagnostic biopsies. Dr Bataille is the Skin Cancer Lead for her trust and the Network Lead for the Hertfordshire Skin Cancer Task Force.