title: Second primary cancers in head and neck cancer patients:  a challenging entity.
authors.forename: Gilberto
authors.initials: G
authors.lastname: de Castro
authors.forename: Ahmad
authors.initials: A
authors.lastname: Awada
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000209:etiology*; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D005260:Female; D006258:Head and Neck Neoplasms / Q000209:etiology*; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D016609:Neoplasms, Second Primary / Q000209:etiology*; D012307:Risk Factors