This section contains statistics on the incidence of malignant melanoma by age and sex, deprivation, geographic variation and trends over time. The ICD codes for malignant melanoma are ICD9 172 and ICD10 C43 and for non-melanoma skin cancer ICD9 173 and C44.
There are two main types of skin cancer, malignant melanoma of the skin and non-melanoma skin cancer (NMSC). Skin cancers are extremely common with around 81,000 new cases registered each year in the UK. In 2004 over 72,000 non-melanoma skin cancers (NMSC) were registered in the UK but registration is known to be incomplete. One study estimated that at least 100,000 cases of NMSC are diagnosed each year 1,2
Malignant melanomas are the least common but most serious type of skin cancer, with more than 8,900 new cases diagnosed in the UK in 2004.3.
Figure 1.1 depicts the percentage distribution of malignant melanoma on parts of the body.
Melanomas can occur in other body organs e.g. the eye. In this section only cutaneous melanomas (ICD10 C43) are discussed.
The majority of NMSCs are either basal cell carcinomas (BCCs), also known as rodent ulcers, or squamous cell carcinomas (SCCs). Both forms are highly treatable and survival rates for NMSCs are over 95%. However, if left untreated, these tumours can become destructive, invading local tissues and causing disfigurement.
Whilst BCCs rarely metastasise, SCC can, and in 2005 there were 511 deaths in the UK from NMSC.4-6 Almost 80% of NMSCs occur in people aged 60 years and over and they constitute a substantial public health problem due to the very large number of cases each year.
The latest statistics show that 4,924 cases of malignant melanoma were diagnosed in women and 4,015 in men in the UK in 2004.7-10 The numbers and rates for the constituent countries of the UK are shown in Table 1.1.3
Unlike most malignancies, malignant melanoma is more common in women than men with a M:F ratio of 4:5. In 2004 it was the sixth most common cancer in females and the tenth in males: for both sexes combined it was the seventh most common cancer.3
The distribution of cases on the body also varies by sex (see Figure 1.1 above): over a third of male cases arise on the trunk of the body, particularly the back, while the most common site for females is on the legs.11
Malignant melanoma is rare in children, while in adults the incidence rates rise steadily with age (Figure 1.2).3
Although the rates are highest in the over 75s, there is a substantial number of cases at younger adult age. Almost a third of all cases occur in people aged less than 50 years and in the age-group 20-39 malignant melanoma is the second most common cancer (when NMSCs are excluded). This is an unusually young age distribution for an adult cancer and emphasises the importance of its prevention and early treatment to avert the potential loss of many years of life. On average, about 20 years of life are lost for each melanoma death.12
Another unusual feature of malignant melanoma is its positive association with affluence.9,13 For Scottish patients diagnosed between 1991-95, age-standardised incidence rates in the most affluent areas were nearly twice as high as those in the most deprived areas (13.6 v 7.4 per 100,000 population).9
In England and Wales between 1988-93, the age-standardised incidence rates for the most deprived areas were between 60-70% lower than those for the most affluent areas.13 If this difference in incidence is related to access to holidays abroad, where high intensity sun exposure is likely, then the gap between different deprivation groups is likely to narrow as more and more people can afford to holiday abroad. In 2005 UK residents made a record 66.2 million trips abroad, three times as many as in 1985. Two-thirds of these foreign visits were holidays and just under half were package holidays.14
Within the UK, the highest overall rates are recorded in Scotland (see Table 1.1 above).
The Cancer Atlas of the UK and Ireland, which analysed rates at local authority and health board level, showed that male and female melanoma incidence rates have a very similar geographical distribution. The highest rates for both sexes occur in south west England, illustrated for men in Figure 1.3.15
Higher than average (UK and Ireland average) melanoma incidence rates were also reported for Northern Ireland, Scotland, Ireland and much of southern England. There is some suggestion that the higher rates in Scotland as well as Northern Ireland and Ireland may reflect better ascertainment of cases: another reason for the elevated rates may be the larger proportion of high risk, fair-skinned people in those populations.15 The Atlas also showed some correlation between areas of low incidence and deprivation.
Around 48,000 new cases of melanoma occur each year in the EU. Within the EU, there is considerable variability of rates as shown in Figure 1.4 with the highest rates for the fairer-skinned north Europeans.16 The UK melanoma incidence rates for both men and women are above the EU average.
World melanoma incidence rates reflect the high risk for white populations in sunny climates with Australia and New Zealand leading the world with age-standardised rates between 30-40 per 100,000 population (Figure 1.5)17 (see risk factors section for incidence rates by ethnicity).
Over the last twenty-five years, the incidence of malignant melanoma has increased more than for any other major cancer in the UK. As Figure 1.6 shows, the male rates have increased almost five times from around 2.5 in 1975 to 12.3 in 2004, while the female rates have more than tripled from 3.9 to 13.8 over the same period in Great Britain.11
When the rates are analysed by age, it can be seen that there have been increases at all ages with the largest increase in the over 65s (Figure 1.7 and Figure 1.8).11
This pattern of increasing malignant melanoma incidence rates, with a faster rate of increase for men than women, is a feature of many fair-skinned populations.18 In Europe, the increases began first with Scandinavia and the UK and then spread to western, southern and eastern Europe.19 In most populations the increase has been mainly for thin melanomas.20,21
Some of the increase may be due to increased surveillance and early detection as well as changes in diagnostic criteria but most is considered to be real and linked to changes in sun behaviour as discussed in the risk factors section.22-24
Benefits from primary prevention are not expected to lead to a significant reduction in incidence for at least two decades although the higher proportion of thinner lesions will have immediate survival benefit (see survival).25
Worldwide the incidence of cutaneous melanoma is increasing faster than any other cancer with an approximate doubling of rates every 10-20 years in countries with white populations.18
The main preventable cause is known but translating this knowledge into changes in behaviour is not easy. Surveys in the UK have revealed that the majority of people regard a sun tan as a sign of health and few are knowledgeable about the dangers of UVR.26 However, there is evidence that there has been modest behavioural change particularly with regard to protecting children from over-exposure to sunlight. More public education is needed especially for high risk groups.
Further research into the many unanswered questions concerning the synthesis of vitamin D from sunlight such as establishing optimal vitamin D levels and how much UVR exposure is required to synthesise different levels of vitamin D, is ongoing. In the UK, the national skin cancer prevention programme, SunSmart, is run by Cancer Research UK and mainly funded by the UK Departments of Health.27