This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oral cavity, Subject name: Surgery
A 80-year-old patient presents with a midline tumor of the lower jaw, involving the alveolar margin. He is edentulous. Treatment of choice is: 
Select and explain. 
A. Hemimandibulectomy, B. Commando operation, C. Segmental mandibulectomy, D. Marginal mandibulectomy
C: Segmental mandibulectomy
Answer: C: Segmental mandibulectomy 
Explanation: Mandibulectomy Marginal Mandibulectomy Segmental Mandibulectomy Conservative mandibulectomy Paial excision of the superior poion of mandible in veical phase Inner coical surface and a poion of underlying medullary cavity is excised Preserve mandibular continuity Indicated when Tumor lies within 1 cm of the mandible or abuts the periosteum without evidence of direct bony invasion Entire segment of mandible is resected. Results in mandibular discontinuity Requires major reconstructive procedure for cosmetic and functional purposes Indications 1. Invasion of the medullary space of the mandible 2. Tumor fixation to the occlusal surface of the mandible in the edentulous patient 3. Invasion to tumor into the mandible the mandibular or mental foramen 4. Tumor fixed to the mandible