Commentary on “Plasma carotenoids and vitamin C concentrations and risk of urothelial cell carcinoma in the European Prospective Investigation into Cancer and Nutrition.” Ros MM, Bueno-de-Mesquita HB, Kampman E, Aben KK, Büchner FL, Jansen EH, van Gils CH, Egevad L, Overvad K, Tjønneland A, Roswall N, Boutron-Ruault MC, Kvaskoff M, Perquier F, Kaaks R, Chang-Claude J, Weikert S, Boeing H, Trichopoulou A, Lagiou P, Dilis V, Palli D, Pala V, Sacerdote C, Tumino R, Panico S, Peeters PH, Gram IT, Skeie G, Huerta JM, Barricarte A, Quirós JR, Sánchez MJ, Buckland G, Larrañaga N, Ehrnström R, Wallström P, Ljungberg B, Hallmans G, Key TJ, Allen NE, Khaw KT, Wareham N, Brennan P, Riboli E, Kiemeney LA, National Institute for Public Health and the Environment, Bilthoven, Netherlands