Editorial : Skin Cancer, Sun and Susceptibility M. J. Moriarty and B. Herity
St. Luke's Hospital and Department of Community Medicine and Epidemiology, U.C.D. Skin cancer is an important malignancy in white skinned populations. In Ireland non melanoma skin cancer (MNSC) is by far the commonest malignancy accounting for about 25% of total new cases ~.2 and being significantly higher thanintheU.K. Malignantmelanoma (MM) is an uncommon tumour but has engendered more public and scientific concern due mainly to its natural history, associated mortality and in particular to its recent rapid increase in incidence in Northern Europe s,* including IrelandL However the number of deaths certified each year as being due to each type of skin cancer is similar at 50-60; 2% of total cancer deaths overall~. The association of both types of skin cancer with exposure to ultra violet (UV) radiation is evidenced by the geographical variation in incidence with high rates in low latitude countries, white populations, outdoor workers and the striking distribution of skin cancer on sun exposed areas of the bodyL In NMSC total cumulative exposure appears to be the most important factors particularly in persons who have light (fair/blonde/red) hair, light eyes (blue/grey/green) and pale skins. In MM intermittent high intensity exposure particularly ifassocated with burning and blistering is the main risk factor9 and is also confirmed in an Irish studyt~ In addition the presence and numbers of pigmented naevi, degree of freckling, family history, presence of light (fair/blond/red) hair and pale skin have been shown to be associated with MM tt. The particular susceptibility of the Irish population to skin cancer has al-
ready been alluded to and the study of Carey & Hogan published in this issue assesses the significance of chronic sun exposure in the pathogenesis of these lesions. This study documents the anatomic distribution of squamous cell carcinoma (SCC) and basal cell (BCC) lesions, and the ratio SCC:BCC in this country as well as studying solar elastosis. They conclude that a significant proportion of these cases were not related to chronic sun exposure and only malignant melanomas (MM) arising in lentigo maligna were associated with long term solar irradiation. In a case control study of risk factors in NMSC in Ireland t2 we found that differences in risk factors between the groups could not explain the high risk to individuals in an Irish populaton. This study therefore agreed with the article in this issue that risk factors other than exposure to UV radiation should be sought for. In this regard Cross t3 indicated the importance of local heat in the pathogenesis of lower limb skin carcinomas in females and these are an interesting but probably decreasing subgroup. In summary, there can be no doubt that avoidance of excessive exposure both chronic and acute to sunlight and artificial forms of UV radiation is still the main preventive measure against the development of both NMSC and MM. In the latter group it is probably now possible to predict a subgroup of the poulation who are at increased risk and in whom public education is particularly important and likely to be of extra benefit in the early detection of these lesions. However as indicated from the study in this issue further research into Irish
39
susceptibility to the development, in particular, of NMSC should be undertaken involving for example epidemiological, pathological and genetic features of an Irish population as compared to other populations such as in the UK and Denmark. References
I. Soathem Tumonr Registry. Report of the Registry Committee for 1985. Cork: 1987. 2. S~ Luke's Hospital. annual Report on n e w patients 1986. (unpublished). 3. Jensen, O. M. and Bolander, A. M. Trends in malignant melanoma of the skin. Wld. Hlth. Stat. Q., 1980: 33, 2-26. 4. Magnus, K. Incidence of malignant melanoma of the skin in Norway, 1955-79. Variation in time and space and solar radiation. Cancer, 1973: 32, 1275-86. 5. Moriarty, M., O'Loughlin, G. et al. Epidemiological features of malignant melanoma in Ireland. Irish J. Med. Sci. 1982: 151, lO, 304307. 6. Central Statistics Office. Report on Vital Statistics 1985. Dublin; Stationery Office, 1988. 7. Fitzpatrick, T. B., Sober, A. J. Sunlight and skin cancer. New Engl, J. Med. 1985: 313, 818-9. 8. Urbach, F. Cancer of the skin, in: Bourke G. J. ed. The Epidemiology of Cancer. Lamdon: Croom Helm, 1983: 102-15. 9. Osterlind, A., "Fucker, M. A. et al. The Danish case control study of cutaneous malignant melanoma L[. Importance of UV light exposure. Int. J. Cancer 1988: 42, 219-24. 10. Herity, Lane, Dunne et al. Case control study of risk factors in malignant melanomas (in preparation). 11. Osterlind, A., Tucker, M. A. et al. The Danish case-control study of cutaneous malignant melanoma I. Importance of host factors. Int. J. Cancer 1988: 42, 200-206. 12. Hedty, B., O'Loughlin, G. et al. Risk factors for non-melanoma skin cancer. Ir. Med. Journal, 1989: 82, 151-2. 13. Cross, F. On a tuff(peat) fine cancer, malignant change superimposed on crythema. Proc. R. Soc. Med. 60, 1307.
St. Luke's Hospital and Department of Community Medicine and Epidemiology, U.C.D. Skin cancer is an important malignancy in white skinned populations. In Ireland non melanoma skin cancer (MNSC) is by far the commonest malignancy accounting for about 25% of total new cases ~.2 and being significantly higher thanintheU.K. Malignantmelanoma (MM) is an uncommon tumour but has engendered more public and scientific concern due mainly to its natural history, associated mortality and in particular to its recent rapid increase in incidence in Northern Europe s,* including IrelandL However the number of deaths certified each year as being due to each type of skin cancer is similar at 50-60; 2% of total cancer deaths overall~. The association of both types of skin cancer with exposure to ultra violet (UV) radiation is evidenced by the geographical variation in incidence with high rates in low latitude countries, white populations, outdoor workers and the striking distribution of skin cancer on sun exposed areas of the bodyL In NMSC total cumulative exposure appears to be the most important factors particularly in persons who have light (fair/blonde/red) hair, light eyes (blue/grey/green) and pale skins. In MM intermittent high intensity exposure particularly ifassocated with burning and blistering is the main risk factor9 and is also confirmed in an Irish studyt~ In addition the presence and numbers of pigmented naevi, degree of freckling, family history, presence of light (fair/blond/red) hair and pale skin have been shown to be associated with MM tt. The particular susceptibility of the Irish population to skin cancer has al-
ready been alluded to and the study of Carey & Hogan published in this issue assesses the significance of chronic sun exposure in the pathogenesis of these lesions. This study documents the anatomic distribution of squamous cell carcinoma (SCC) and basal cell (BCC) lesions, and the ratio SCC:BCC in this country as well as studying solar elastosis. They conclude that a significant proportion of these cases were not related to chronic sun exposure and only malignant melanomas (MM) arising in lentigo maligna were associated with long term solar irradiation. In a case control study of risk factors in NMSC in Ireland t2 we found that differences in risk factors between the groups could not explain the high risk to individuals in an Irish populaton. This study therefore agreed with the article in this issue that risk factors other than exposure to UV radiation should be sought for. In this regard Cross t3 indicated the importance of local heat in the pathogenesis of lower limb skin carcinomas in females and these are an interesting but probably decreasing subgroup. In summary, there can be no doubt that avoidance of excessive exposure both chronic and acute to sunlight and artificial forms of UV radiation is still the main preventive measure against the development of both NMSC and MM. In the latter group it is probably now possible to predict a subgroup of the poulation who are at increased risk and in whom public education is particularly important and likely to be of extra benefit in the early detection of these lesions. However as indicated from the study in this issue further research into Irish
39
susceptibility to the development, in particular, of NMSC should be undertaken involving for example epidemiological, pathological and genetic features of an Irish population as compared to other populations such as in the UK and Denmark. References
I. Soathem Tumonr Registry. Report of the Registry Committee for 1985. Cork: 1987. 2. S~ Luke's Hospital. annual Report on n e w patients 1986. (unpublished). 3. Jensen, O. M. and Bolander, A. M. Trends in malignant melanoma of the skin. Wld. Hlth. Stat. Q., 1980: 33, 2-26. 4. Magnus, K. Incidence of malignant melanoma of the skin in Norway, 1955-79. Variation in time and space and solar radiation. Cancer, 1973: 32, 1275-86. 5. Moriarty, M., O'Loughlin, G. et al. Epidemiological features of malignant melanoma in Ireland. Irish J. Med. Sci. 1982: 151, lO, 304307. 6. Central Statistics Office. Report on Vital Statistics 1985. Dublin; Stationery Office, 1988. 7. Fitzpatrick, T. B., Sober, A. J. Sunlight and skin cancer. New Engl, J. Med. 1985: 313, 818-9. 8. Urbach, F. Cancer of the skin, in: Bourke G. J. ed. The Epidemiology of Cancer. Lamdon: Croom Helm, 1983: 102-15. 9. Osterlind, A., "Fucker, M. A. et al. The Danish case control study of cutaneous malignant melanoma L[. Importance of UV light exposure. Int. J. Cancer 1988: 42, 219-24. 10. Herity, Lane, Dunne et al. Case control study of risk factors in malignant melanomas (in preparation). 11. Osterlind, A., Tucker, M. A. et al. The Danish case-control study of cutaneous malignant melanoma I. Importance of host factors. Int. J. Cancer 1988: 42, 200-206. 12. Hedty, B., O'Loughlin, G. et al. Risk factors for non-melanoma skin cancer. Ir. Med. Journal, 1989: 82, 151-2. 13. Cross, F. On a tuff(peat) fine cancer, malignant change superimposed on crythema. Proc. R. Soc. Med. 60, 1307.
