Sunshine is Really Good for You After all — And Prevents Cancer

Berwick M, Armstrong BK, Ben-Porat L, Fine J, Kricker A, Eberle C, Barnhill R. Sun exposure and mortality from melanoma. J Natl Cancer Inst. 2005 Feb 2;97(3):195-9.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15687362

ABSTRACT

BACKGROUND: Melanoma incidence and survival are positively associated, both geographically and temporally. Solar elastosis, a histologic indicator of cutaneous sun damage, has also been positively associated with melanoma survival. Although these observations raise the possibility that sun exposure increases melanoma survival, they could be explained by an association between incidence and early detection of melanoma. We therefore evaluated the association between measures of skin screening and death from cutaneous melanoma.

METHODS: Case subjects (n = 528) from a population-based study of cutaneous melanoma were followed for an average of more than 5 years. Data, including measures of intermittent sun exposure, perceived awareness of the skin, skin self-screening, and physician screening, were collected during in-person interviews and review of histopathology and histologic parameters (i.e., solar elastosis, Breslow thickness, and mitoses) for all of the lesions. Competing risk models were used to compute risk of death (hazard ratios [HRs], with 95% confidence intervals [CIs]) from melanoma. All statistical tests were two-sided.

RESULTS: Sunburn, high intermittent sun exposure, skin awareness histories, and solar elastosis were statistically significantly inversely associated with death from melanoma. Melanoma thickness, mitoses, ulceration, and anatomic location on the head and neck were statistically significantly positively associated with melanoma death. In a multivariable competing risk analysis, skin awareness (with versus without, HR = 0.5, 95% CI = 0.3 to 0.9, P = .022) and solar elastosis (present versus absent, HR = 0.4, 95% CI = 0.2 to 0.8, P = .009) were strongly and independently associated with melanoma death after adjusting for Breslow thickness, mitotic index, and head and neck location, which were also independently associated with death.

CONCLUSIONS: Sun exposure is associated with increased survival from melanoma.

Smedby KE, Hjalgrim H, Melbye M, Torrang A, Rostgaard K, Munksgaard L, Adami J, Hansen M, Porwit-MacDonald A, Jensen BA, Roos G, Pedersen BB, Sundstrom C, Glimelius B, Adami HO. Ultraviolet radiation exposure and risk of malignant lymphomas. J Natl Cancer Inst. 2005 Feb 2;97(3):199-209.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15687363

ABSTRACT

BACKGROUND: The incidence of malignant lymphomas has been increasing rapidly, but the causes of these malignancies remain poorly understood. One hypothesis holds that exposure to ultraviolet (UV) radiation increases lymphoma risk. We tested this hypothesis in a population-based case-control study in Denmark and Sweden.

METHODS: A total of 3740 patients diagnosed between October 1, 1999, and August 30, 2002, with incident malignant lymphomas, including non-Hodgkin lymphoma, chronic lymphocytic leukemia, and Hodgkin lymphoma, and 3187 population controls provided detailed information on history of UV exposure and skin cancer and information on other possible risk factors for lymphomas. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by logistic regression. Statistical tests were two-sided.

RESULTS: Multivariable-adjusted analyses revealed consistent, statistically significant negative associations between various measures of UV light exposure and risk of non-Hodgkin lymphoma. A high frequency of sun bathing and sunburns at age 20 years and 5-10 years before the interview and sun vacations abroad were associated with 30%-40% reduced risks of non-Hodgkin lymphoma (e.g., for sunbathing four times a week or more at age 20 versus never sunbathing, OR = 0.7, 95% CI = 0.6 to 0.9; for two or more sunburns a year at age 20 versus no sunburns, OR = 0.6, 95% CI = 0.5 to 0.8). These inverse associations increased in strength with increasing levels of exposure (all P(trend)< or =.01). Similar, albeit weaker, associations were observed for Hodgkin lymphoma. There were no clear differences among non-Hodgkin lymphoma subtypes, although associations were stronger for B-cell than for T-cell lymphomas. A history of skin cancer was associated with a doubling in risks of both non-Hodgkin and Hodgkin lymphoma.

CONCLUSIONS: A history of high UV exposure was associated with reduced risk of non-Hodgkin lymphoma. The positive association between skin cancer and malignant lymphomas is, therefore, unlikely to be mediated by UV exposure.