“…Possibly, viral infections in VAD animals contribute to the development of pre-neoplastic changes in the lung that can, in some cases, progress to high-grade dysplasia and carcinoma [ 60 , 61 ]. The relationship between lung cancer and vitamin A precursors has been previously examined [ 62 , 63 , 64 , 65 , 66 ], and (as for other cancers) vitamin supplementation as a treatment for lung cancer has yielded variable results [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 ].…”