A 52-year-old man from Delhi presents with a 3-month history of progressive dysphagia and retrosternal discomfort. Upper endoscopy reveals a 4 cm ulcerated lesion in the lower third of the esophagus. Biopsy confirms squamous cell carcinoma. CT chest and abdomen shows the tumor invades the muscularis propria but does not breach the adventitia. There is no evidence of regional lymph node involvement or distant metastasis. What is the TNM stage of this tumor?