Table 1.

Detailed search strategy of Cochrane Library.

Number	Search terms
1	MeSH descriptor: (Lung Neoplasms) explode all trees
2	MeSH descriptor: (Skin Neoplasms) explode all trees
3	((Neoplasm, Lung∗) or (Lung Neoplasm∗) or (Neoplasm, Pulmonary ∗) or (Pulmonary Neoplasm∗) or (Lung Cancer∗) or (Cancer, Lung∗) or (Pulmonary Cancer∗) or (Cancer, Pulmonary∗) or (Cancer of Lung ∗) or (Lung Carcinoma, Non-Small-Cell∗) or (Non Small Cell Lung Carcinoma∗) or (Non-Small Cell Lung Cancer∗) or (Skin Cancer∗) or (Cutaneous Cancer∗) or (Cutaneous Malignancy∗) or (Skin Neoplasms∗) or (Skin Metastasis∗)):ti, ab, kw
4	Or 1–3
5	MeSH descriptor: (Vitamin D) explode all trees
6	((Vitamin D∗) or (25-hydroxuvitain D∗) or (25(OH) vitamin D∗)):ti, ab, kw
7	Or 5–6
8	MeSH descriptor: (Case-control Studies) explode all trees
9	((Case-control Study∗) or (Case-referent Study∗) or (Case-controlled Study∗) or (Observational Study∗) or (Cohort Study∗) or (Studies∗)):ti, ab, kw
10	Or 8–9
11	4 and 7 and 10