The Network of Cancer Genes (NCG) is a manually curated repository of 2372 genes whose somatic modifications have known or predicted cancer driver roles. These genes were collected from 275 publications, including two sources of known cancer genes and 273 cancer sequencing screens of more than 100 cancer types from 34,905 cancer donors and multiple primary sites. This represents a more than 1.5-fold content increase compared to the previous version. NCG also annotates properties of cancer genes, such as duplicability, evolutionary origin, RNA and protein expression, miRNA and protein interactions, and protein function and essentiality. NCG is accessible at http://ncg.kcl.ac.uk/.Electronic supplementary materialThe online version of this article (10.1186/s13059-018-1612-0) contains supplementary material, which is available to authorized users.

The Network of Cancer Genes (NCG) is a manually curated repository of 2,372 genes whose somatic modifications have a known or predicted cancer driver role.These genes were collected from 275 publications, including two sources of known cancer genes and 273 cancer sequencing screens of 119 cancer types in 31 primary sites from 34,905 cancer donors. This represents a more than 1.5-fold increase in content as compared to the previous version. NCG also annotates properties of cancer genes, such as duplicability, evolutionary origin, RNA and protein expression, miRNA and protein interactions, protein function and essentiality. NCG is accessible at http://ncg.kcl.ac.uk/.

Vitamin D synthesis by exposure of skin to solar ultraviolet radiation (UVR) provides the majority of this hormone that is essential for bone development and maintenance but may be important for many other health outcomes. This process, which is the only wellestablished benefit of solar UVR exposure, depends on many factors including genetics, age, health, and behavior. However, the most important factor is the quantity and quality of UVR reaching the skin. Vitamin D synthesis specifically requires ultraviolet B (UVB) radiation that is the minority component (<5%) of solar UVR. This waveband is also the most important for the adverse effects of solar exposure. The most obvious of which is sunburn (erythema), but UVB is also the main cause of DNA damage to the skin that is a prerequisite for most skin cancers. UVB at the Earth's surface depends on many physical and temporal factors such as latitude, altitude, season, and weather. Personal, cultural, and behavioral factors are also important. These include skin melanin, clothing, body surface area exposed, holiday habits, and sunscreen use. There is considerable disagreement in the literature about the role of some of these factors, possibly because some studies have been done by researchers with little understanding of photobiology. It can be argued that vitamin D supplementation obviates the need for solar exposure, but many studies have shown little benefit from this approach for a wide range of health outcomes. There is also increasing evidence that such exposure offers health benefits independently of vitamin D: the most important of which is blood-pressure reduction. In any case, public health advice must optimize risk versus benefit for solar exposure. It is fortunate that the individual UVB doses necessary for maintaining optimal vitamin D status are lower than those for sunburn, irrespective of skin melanin.

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