A 62-year-old male with a 40 pack-year smoking history presents with a 4-month history of progressive hoarseness and stridor. Flexible laryngoscopy reveals a 1.5 cm sessile, white lesion on the right vocal cord with intact cord mobility and no involvement of the anterior commissure or arytenoid. The lesion is confined to the vocal cord. Biopsy confirms squamous cell carcinoma. Staging CT shows no distant metastases and no pathologically enlarged lymph nodes. What is the most appropriate primary treatment for this patient?