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Abstract
Introduction The incidence and mortality rates of cutaneous melanoma (CM) are increasing among fair-skinned populations worldwide. Ultraviolet radiation (UVR) is the principal risk factor for CM, but is also the main source of 25-hydroxyvitamin D (25(OH)D), which has been associated with reduced risk and better prognosis of some cancer types. However, both low and high 25(OH)D levels have been associated with increased risk of CM. Obesity as measured by body mass index (BMI) is associated with risk of several cancers and has also been suggested as a risk factor for CM, and may also be related to insufficient 25(OH)D and/or high leptin levels. Moreover, contracting a CM diagnosis has been associated with increased risk of developing second cancer. We aim to study whether low prediagnostic serum levels of 25(OH)D, high prediagnostic levels of BMI and high serum leptin levels influence CM incidence, Breslow thickness and CM mortality, and risk of second cancer and survival after a CM diagnosis.
Methods and analysis Cohort and nested case–control studies will be carried out using the population-based Janus Serum Bank Cohort (archival prediagnostic sera, BMI, smoking and physical activity), with follow-up from 1972 to 2014. Additional data will be received from the Cancer Registry of Norway, the national Cause of Death Registry, Statistics Norway (education and occupation) and exposure matrices of UVR. Time-to-event regression models will be used to analyse the cohort data, while the nested case–control studies will be analysed by conditional logistic regression. A multilevel approach will be applied when incorporating group-level data.
Ethics and dissemination The project is approved by the Regional Committee for Medical Research Ethics and is funded by the Norwegian Cancer Society. Results will be published in peer-reviewed journals, at scientific conferences and in the news media.
- Vitamin D
- 25-hydroxyvitamin D
- leptin
- serum samples
- Obesity
- body mass index
- ultraviolet radiation
- melanoma
- incidence
- mortality
- second cancer
- survival
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Footnotes
Contributors TER conceived the study. JSS, TKG, JRR, LV, RB, MBV and TER contributed to the project design. TER and JSS are responsible for data acquisition. JSS and TER drafted the manuscript, and MBV, TKG, JRR, LV and RB reviewed and revised it critically for important intellectual content and approved the final version for submission. JSS and TER are the guarantors.
Funding The research project has been reviewed and granted funding by the Norwegian Cancer Society (no 5829980-2014) and the Cancer Registry of Norway Research Fund.
Competing interests None declared.
Ethics approval This project has approval from the Regional Committee for Medical and Health Research Ethics (no 2014/185).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Requests for data sharing/case pooling may be directed to the corresponding author. This project uses third-party data derived from State government registries, which are ultimately governed by their ethics committees and data custodians. Thus, any requests to share these data will be subject to formal approval from each data source used in this project.
Correction notice This paper has been amended since it was published Online First. Owing to a scripting error, some of the publisher names in the references were replaced with 'BMJ Publishing Group'. This only affected the full text version, not the PDF. We have since corrected theseerrors and the correct publishers have been inserted into the references.