Non-melanoma skin cancer (NMSC) was the most common cancer in Ireland, accounting for 27% of all malignant neoplasms (Table 3.1). The average number of new cases diagnosed each year was 3,777 in women and 4,294 in men. During 1995-2007, the number of new cases increased by approximately 3% per annum; since 2002 it has been increasing by around 6% in RoI.
The risk of developing NMSC before the age of 75 was 1 in 12 for women and 1 in 8 for men and was slightly higher in RoI than in NI for both men and women. At the end of 2008, 11,629 women and 12,375 men aged under 65, and 30,748 women and 31,937 men aged 65 and over, were alive up to 15 years after their cancer diagnosis.
Table 3.1 Summary information for non-melanoma skin cancer in Ireland, 1995-2007
Ireland | RoI | NI | ||||
females | males | females | males | females | males | |
% of all new cancer cases | 27% | 28% | 28% | 29% | 24% | 27% |
average number of new cases per year | 3777 | 4294 | 2666 | 3080 | 1111 | 1215 |
cumulative risk to age 74 | 8.6% | 12.2% | 9.3% | 12.9% | 7.1% | 10.5% |
15-year prevalence (1994-2008) | 42377 | 44312 | 29736 | 31028 | 12641 | 13284 |
The incidence of NMSC increased with increasing age (Figure 3.1). The age distribution was similar for men and women and for RoI and NI. Only approximately 10% of cases occurred in those aged under 50 years and the largest number of cases for both sexes presented in the 70–79 age group.
Figure 3.1 Age distribution of non-melanoma skin cancer cases in Ireland, 1995-2007, by sex
No reliable data are available on international variations in non-melanoma skin cancer incidence.
Table 3.2 Risk factors for non-melanoma skin cancer, by direction of association and strength of evidence
Increases risk | Decreases risk | |
Convincing or probable | Sun exposure1,2 | |
| Skin colour2 | |
| Ability to tan2 | |
| Childhood freckling2 | |
| Presence of benign sun damage in the skin2 | |
| Sunbed/sunlamp use3 | |
| Immune suppression4 and some immunosuppressive drugs5 | |
| Infection with human papilloma viruses (HPV)6 | |
| Human immunodeficiency virus, type 1 (HIV-1)6 | |
| Methoxsalen5,7 | |
| Arsenic and inorganic arsenic compounds8 | |
| Ionizing radiation9 | |
Possible | Statins10 | |
1 International Agency for Research on Cancer, 1992; 2 Armstrong and Kricker, 2001; 3 Karagas et al., 2002; 4 Saladi and Persaud, 2005; 5 International Agency for Research on Cancer, 2011a; 6 International Agency for Research on Cancer, 2011b; 7 together with UV light; 8 Straif et al., 2009; 9 El Ghissassi et al., 2009; 10Kuoppala et al., 2008 |
Individuals who are immune suppressed, such as organ transplant recipients or those with AIDS, have a greatly increased risk of developing NMSC. Positivity for the human immunodeficiency virus, type 1 (HIV-1) is a cause of NMSC. Some immunosuppressive drugs—including azathioprine and ciclosporin—which are used to prevent organ rejection following transplant, or to treat autoimmune diseases such as rheumatoid arthritis and Crohn’s disease, are recognised to cause skin cancer. Risk of NMSC is also increased by exposure to the drug methoxsalen, which is used to treat some skin conditions, in combination with UV light. Residues of arsenic from agriculture, mining and industrial practices can end up in drinking water. Arsenic is carcinogenic (International Agency for Research on Cancer, 1987; International Agency for Research on Cancer, 2004a) and ingestion of arsenic and inorganic arsenic compounds causes NMSC. Low-dose ionizing radiation exposure (e.g. for benign skin conditions such as acne) increases risk of BCC.The two main types of non-melanoma skin cancer are squamous cell carcinoma (SCC) and basal cell carcinomas (BCC). Both types are caused by exposure to ultraviolet (UV) radiation present in sunlight. Occupational sunlight exposure has been mainly associated with SCC and recreational exposure with BCC. Individuals with a lighter skin colour, less ability to tan, and who had freckles as a child, are at increased risk, as are those with solar keratoses (benign sun damage to the skin). Independently of sun exposure, use of artificial tanning devices which emit UV radiation, such as sunbeds or sunlamps, has been associated with raised risk of BCC and, especially, SCC.
Human papilloma viruses (HPV) infect mucosal and cutaneous epithelia. Infection with particular HPV types (genus-beta types and specifically HPV5 and HPV8) may be causally related to NMSC (International Agency for Research on Cancer, 2011b). People who use statins may have an increased risk of NMSC (although the possibility that the association could be due to different levels of contact with health services among users and non-users of statins cannot be discounted).
Non-melanoma skin cancer had a strong geographical pattern, which was similar for men and women (Maps 3.1-3.3).
Regions of high relative risk were mainly seen in coastal areas, particularly along the east coast from Down to Wicklow, the south and west coasts from Waterford to Mayo and in Sligo (men) and Donegal. Areas of higher relative risk were also seen around the cities of Dublin, Waterford, Cork, Limerick and Galway.
Map 3.1 Non-melanoma skin cancer, smoothed relative risks: both sexes
Map 3.2 Non melanoma skin cancer, smoothed relative risks: males
Map 3.3 Non melanoma skin cancer, smoothed relative risks: females