HMOX1 and head and neck cancer: HO-1 may play a protumor role in most tumor types, as demonstrated in some gastrointestinal cancers [43,44,45,46,47], glioma [48], head and neck cancer [49], lung cancer [50,51], thyroid cancer [52], genitourinary cancers [53,54,55,56], melanoma [57] and hematological malignancies [58,59].