Here’s a list of studies about vitamin D and lung cancer:
Could Ultraviolet B Irradiance and Vitamin D be Associated With Lower Incidence Rates of Lung Cancer? (2008)
Conclusion: Lung cancer incidence rates were investigated in 111 different countries. Lung cancer rates were found to be higher in latitudes farther from the equator and in areas with higher cloud cover. These would also be areas of the world that receive less solar UVB radiation, which is necessary for vitamin D production.
Seasonal and Geographical Variations in Lung Cancer Prognosis in Norway. Does Vitamin D from the Sun Play a Role? (2007)
Conclusion: An investigation of lung cancer incidence rates in Norway found that patients diagnosed in autumn have a lower fatality rate than those diagnosed in winter – winter being when most people’s vitamin D levels drop.
Circulating 25-hydroxyvitamin D Levels Predict Survival in Early-Stage Non-Small-Cell Lung Cancer Patients (2007)
Conclusion: 447 early-stage non-small-cell lung cancer patients were observed for an average of 6 years and it was found that those with higher vitamin D levels and higher vitamin D intake had higher survival rates than those with lower vitamin D levels and lower vitamin D intake.