CORRESPONDENCE

Re: Sun Exposure and Mortality From Melanoma

Philippe Autier, Gianluca Severi, Mathieu Boniol, Esther de Vries, Jan-Willem Coebergh, Jean-François Doré

Affiliations of authors: Unit of Epidemiology, Prevention and Screening, Jules Bordet Institute, Brussels, Belgium (PA); Cancer Epidemiology Centre, The Cancer Council Victoria, Carlton, Australia (GS); International Agency for Research on Cancer (IARC), Lyons, France (MB); Department of Public Health, Erasmus University MC, Rotterdam, The Netherlands (EdV); Comprehensive Cancer Centre South (IKZ), Eindhoven, The Netherlands (J-WC); Institut National de la Santé et de la Recherche Médicale Unit 590, Centre Léon Bérard, Lyon, France (JFD)

Correspondence to: Philippe Autier, MD, Unit of Epidemiology and Prevention, Jules Bordet Institute, 121 Bd of Waterloo, Brussels 1000 (e-mail: Philippe.autier{at}bordet.be).

The study by Berwick et al. (1) suggests that high sun exposure is associated with increased survival of patients with cutaneous melanoma, independent of prognostic factors, such as Breslow thickness or anatomic location. The presence of solar elastosis in the skin specimen harboring the melanoma was the sun exposure indicator that was mainly associated with increased survival. Similar to solar keratoses, solar elastosis is more prevalent on chronically sun-exposed skin, and it increases sharply after age 50 years (2).

Sun exposure is recognized as the main environmental cause of the melanoma epidemic that has stricken white populations since 1950. Melanomas in body sites chronically exposed to the sun (e.g., head and neck) are the most prevalent at older ages, whereas melanomas in body sites exposed to intermittent sun exposure are the most prevalent melanomas in people younger than 50 years (3). This suggests that intermittent sun exposure has a greater potential to cause melanomas at younger ages than chronic sun exposure. There is now evidence that skin normally covered by clothing is more sensitive to solar radiation than skin normally exposed to the sun (4) and that melanoma may arise from different biologic pathways (5,6). These elements prompt us to hypothesize that some melanomas could be associated with intermittent sun exposure and with the numbers and size of acquired nevi that develop during childhood and adolescence and would mainly occur on covered skin areas (e.g., the trunk). Other melanomas could be associated with chronic sun exposure and thus also with solar keratoses and solar elastosis and would mainly occur on uncovered body sites (e.g., the head). The results of Berwick et al. (1) suggest that tumors that arise more as a consequence of chronic sun exposure have a less aggressive phenotype than tumors that arise more as a consequence of intermittent sun exposure.

This suggestion is supported by the observation that lentigo melanoma (excluded in the study by Berwick et al.) is often associated with squamous cell skin cancer, solar keratosis, and chronic sun exposure. Lentigo melanoma has a less aggressive clinical course than nodular and superficial spreading melanoma. To test the possible effect of type of sun exposure (chronic versus intermittent) on survival of melanoma patients, it would be important to know whether indicators of intermittent sun exposure were associated with survival (with and without including solar elastosis in the model). It would also be important to know the age and body site distribution of melanomas separately for melanomas with and without signs of solar elastosis and whether solar elastosis was associated with indicators of intermittent sun exposure.

From a public health point of view, however, the findings of Berwick et al. do not bring any motive for changing the prevention messages aiming to control the incidence of cutaneous melanoma through reductions in sun exposure.

REFERENCES

(1) Berwick M, Armstrong BK, Ben-Porat L, Fine J, Kricker A, Eberle C, et al. Sun exposure and mortality from melanoma. J Natl Cancer Inst 2005;97:195–9.[Abstract/Free Full Text]

(2) Larsen TE, Grude TH. A retrospective histological study of 669 cases of primary cutaneous malignant melanoma in clinical stage I. The relation of dermal solar elastosis to sex, age and survival of the patient and to localization, histological type and level of invasion of the tumour. Acta Pathol Microbiol Scand [A] 1979;87A:361–6.[ISI]

(3) Elwood JM, Gallagher RP. Body site distribution of cutaneous malignant melanoma in relationship to patterns of sun exposure. Int J Cancer 1998;78:276–80.[CrossRef][ISI][Medline]

(4) Autier P, Boniol M, Severi G, Giles G, Cattaruzza MS, Luther H, et al. The body site distribution of melanocytic naevi in 6-7 year old European children. Melanoma Res 2001;11:123–31.[CrossRef][ISI][Medline]

(5) Bataille V, Sasieni P, Grulich A, Swerdlow A, McCarthy W, Hersey P, et al. Solar keratoses: a risk factor for melanoma but negative association with melanocytic naevi. Int J Cancer 1998;78:8–12.[CrossRef][ISI][Medline]

(6) Whiteman DC, Watt P, Purdie DM, Hughes MC, Hayward NK, Green AC. Melanocytic nevi, solar keratoses, and divergent pathways to cutaneous melanoma. J Natl Cancer Inst 2003;95:806–12.[Abstract/Free Full Text]



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