Table 3.

Studies on the investigation of the old vitamin D role in combating lung cancer.

Study Type	Study Design	Parameter Examined	Findings	Ref
Clinical Studies	Double-blind, randomized trial, Vitamin D 1200 IU/d (n = 77) v/s placebo (n = 78)	Overall survival and relapse-free survival.	Patients with early-stage lung adenocarcinoma may benefit from vitamin D therapy.	[82]
Preclinical Studies	A/J Mouse model, Vitamin D3 (2.5 or 5 microgram/Kg diet)	Tumor incidence and tumor cell differentiation.	Reduces incidence of the tumor as well as having combating potential against lung carcinogenesis.	[83]
	Mouse model of N-nitroso-tris-chloroethyl urea; Vitamin D3 2000 IU/Kg.	The premalignant tumors progressing of Carcinoma	Reduces proliferation, development of premalignant lesion, swelling of squamous cell carcinoma of the lung.	[84]
In vitro studies	NCI-H1975 and A549 tumor cells	Metastasis, tumor cell apoptosis.	The tumor cell growth, infiltration, and metastasis are inhibited, while tumor cell apoptosis is promoted.	[85]