MedicalResearch.com Interview with:
Reza Ghiasvand, PhD
Oslo Centre for Biostatistics and Epidemiology
Faculty of Medicne
University of Oslo
MedicalResearch.com: What is the background for this study?
Response: Melanoma is the most dangerous type of skin cancer. It is estimated that about 288,000 individuals will be diagnosed and about 61,000 will die from it in 2018, with the majority of patients in Australia, New Zealand, Europe and North America. Ultraviolet (UV) exposure (from both the sun and tanning beds) is the most important preventable risk factor for melanoma. However, the association between UV exposure and melanoma is complex and does not accord with a simple model in which risk increases directly with exposure. An individual risk of melanoma also depends on personal characteristics such as skin color and skin sensitivity to the UV exposure, hair color, number of moles, and age.
It has been hypothesized that the pattern of UV exposure may play a role in melanoma development in different body sites. For example, melanoma on the trunk (chest and back) has been linked to the recreational UV exposure such as sunbathing and frequent sunburns in people with high number of moles on their body. In contrast, melanomas on the head and neck have been linked to constant sun exposure such as occupational UV exposure, mainly in older people. Epidemiologic and molecular evidence in support of this hypothesis has been published based on analyses of small datasets. Also, melanoma on legs and arms is less studied under this hypothesis.
In our study, we examined UV exposure (sunbathing, sunburn and sunbed use) and pigmentary factors (skin, eye, and hair color, freckling, and number of moles), and risk of melanoma on different body sites. We used information from the Norwegian Women and Cancer Study, a population-based cohort study that started in 1991, and includes more than 161,000 Norwegian women followed for an average of 18 years.
MedicalResearch.com: What are the main findings?
- Number of sunbathing vacations and sunbed sessions were associated with a higher risk of melanoma on the trunk and legs, but not on arms and head/neck. Sunbathing vacation before age 20 years was associated with significantly increased risk of melanoma on legs.
- Fair skin color, light hair color, high number of moles and history of sunburn were associated with higher risk of melanoma on all body sites.
- Our findings suggest that determinants of melanoma on legs are more similar to the trunk, while determinants of upper limb melanoma are more similar to head/neck.
MedicalResearch.com: What should readers take away from your report?
Response: The legs are the most common site of melanoma among women. Our findings suggest that avoiding excess sun exposure and sunbed use can reduce the risk of melanoma on legs. Moreover, our finding that sunbathing vacation before age 20 years is associated with significantly increased risk of melanoma on legs highlights the importance of starting sun protection early in life.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: I would encourage researchers to replicate this study in men. Our study included only women and we cannot extrapolate the findings to men since their site-specific pattern of sun exposure differs from that in women.
Disclosures: This study was funded by the Norwegian Cancer Society and the funding source had no role in study design, data analysis, data interpretation, or writing of the report.
The authors have no conflicts of interest to declare.
Ghiasvand R, Robsahm TE, Green AC, et al. Association of Phenotypic Characteristics and UV Radiation Exposure With Risk of Melanoma on Different Body Sites. JAMA Dermatol. Published online November 21, 2018. doi:10.1001/jamadermatol.2018.3964
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