A 62-year-old woman with a 20-year history of betel nut and tobacco chewing presents with a 3-month history of a painful ulcer on the left lateral border of the tongue. Examination shows an indurated ulcer with rolled margins, and palpation reveals a hard, fixed mass. Cervical lymph nodes are enlarged and firm. Biopsy confirms well-differentiated squamous cell carcinoma. CT imaging shows no distant metastases. The patient is counseled regarding treatment options. Which of the following is the most appropriate initial management for this T3N2M0 oral tongue cancer?