Long-term Ultraviolet Flux, Other Potential Risk Factors, and Skin Cancer Risk: A Cohort Study

Abstract

Background Few prospective studies have examined the relationship between sun exposure, other potential risk factors, and risk of different skin cancers [including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma] simultaneously. Methods We evaluated the association between a number of potential risk factors and skin cancer risk in a cohort of 108,916 US women, the Nurses’ Health Study II (1989-2009). Results During 2.05 million years of follow-up, we identified 6,955, 880, and 779 diagnoses of BCC, SCC, and melanoma, respectively. Compared to participants in the lowest quintile of cumulative ultraviolet flux in adulthood, participants in the highest quintile had multivariable-adjusted relative risks (RR) of 2.35 (Ptrend<0.0001) for BCC, 2.53 (Ptrend=0.009) for SCC, and 0.68 (Ptrend=0.38) for melanoma. In contrast, the RRs were 1.68 (95%CI: 1.55-1.82) for BCC, 1.68 (95%CI: 1.34-2.11) for SCC and 1.80 (95%CI: 1.42-2.28) for melanoma for participants with ≥5 blistering sunburns when compared to participants without sunburn between ages 15-20. We found significant interactions between family history of melanoma, number of blistering sunburns between ages 15-20 and BCC risk, and between sunburn reaction as a child/adolescent and SCC risk (all Pinteraction<0.05). Conclusion In a cohort of US women, we found that sun exposures in both early life and adulthood were predictive of BCC and SCC risks, whereas melanoma risk was predominantly associated with sun exposure in early life. Impact Our results may have potential implications for the prevention of skin cancers.

History of Keratinocyte Carcinoma and Risk of Melanoma: A Prospective Cohort Study

“…Interestingly, the association was more apparent among participants who lived in areas with lower annual UV flux. High levels of cumulative UV flux have been associated with increased risk of melanoma in previous studies (21,26). It is thus plausible that having a history of KC may represent a more susceptible state and could raise the risk of melanoma more substantially among individuals with lower UV exposure.…”

“…30.0 g/day), citrus consumption (quintiles), and caffeine intake (quintiles). To avoid overadjustment, a host risk score was created for each participant using cohort-derived hazard ratios associated with each of the six host risk factors of melanoma (ie, ethnicities, family history of melanoma, natural hair color, number of moles on arms, skin reaction after prolonged sun exposure as a child/adolescent, and number of severe or blistering sunburns) (21) and was adjusted in the models as quintiles. A meta-analysis approach was used to combine the risk estimates in different cohorts using a random effect model.…”

“…Information on dietary factors, including consumption of citrus products, alcohol, and coffee, was repeatedly collected using a validated food frequency questionnaire at least every four years during the follow-up (17). Data on the following phenotypic and sun exposure-related factors were also collected in the follow-up questionnaires: ethnicities; family history of melanoma in first-degree relatives (parents, siblings, or offspring); natural hair color at an early age (age 21 years in NHS, and age 18 years in NHSII/HPFS); number of moles on extremity (arms in NHS/HPFS and legs in NHSII); skin reaction after prolonged sun exposure as a child/adolescent; number of severe or blistering sunburns; average time spent in direct sunlight in summer months since high school; regular use of sunscreen in summer months; and cumulative UV flux since baseline (a measure of long-term UV exposure) (14,17,21).…”

“…In the model analysis, we controlled for a set of host, environmental, lifestyle, and dietary factors, most of which have been associated with risk of melanoma or KC in previous epidemiologic studies ( [14][15][16]21,[23][24][25]. Interestingly, the association was more apparent among participants who lived in areas with lower annual UV flux.…”

Skin colour: No hiding in the dark

“…For those with skin rich in eumelanin, this typically results in a tan. But for many pheomelanin-rich white people, burning and blistering is more common -and the risk of melanoma jumps for every blistering sunburn experienced during childhood 3 . But pheomelanin can cause cancer even in the absence of ultraviolet light, says David Fisher, director of the melanoma programme at the Massachusetts General Hospital Cancer Center in Boston.…”