A 58-year-old male farmer from rural Maharashtra presents with a 4-month history of a non-healing ulcer on the left buccal mucosa. He reports a 20 pack-year smoking history and chews betel quid daily. On examination, the ulcer measures 2.5 cm × 2 cm with rolled, indurated margins and a granular base. Regional lymph nodes are palpable and firm. Biopsy confirms squamous cell carcinoma. CT staging shows the tumour confined to the buccal mucosa with ipsilateral level I lymph node involvement (no distant metastases). According to TNM 8 classification, what is the stage of this carcinoma?

Explanation

## TNM 8 Staging for Oral Cavity Carcinoma **Key Point:** The TNM 8 classification for oral cavity carcinoma incorporates both tumour size/depth and nodal involvement. This patient has T2N1M0 disease, which corresponds to Stage III. ### T-Stage Assessment - **T1:** Tumour ≤2 cm in greatest dimension, depth of invasion (DOI) ≤5 mm - **T2:** Tumour >2 cm but ≤4 cm in greatest dimension, OR DOI >5 mm but ≤10 mm - **T3:** Tumour >4 cm in greatest dimension, OR DOI >10 mm - **T4a:** Tumour invades adjacent structures (bone, deep muscle, maxillary sinus, skin) - **T4b:** Tumour invades masticator space, pterygoid plates, or skull base This patient's tumour is 2.5 cm × 2 cm (>2 cm), making it **T2** (assuming DOI >5 mm, which is typical for a granular ulcerative lesion with indurated margins). ### N-Stage Assessment - **N0:** No regional lymph node metastasis - **N1:** Metastasis in a single ipsilateral lymph node, ≤3 cm - **N2a:** Metastasis in a single ipsilateral lymph node, >3 cm but ≤6 cm - **N2b:** Metastasis in multiple ipsilateral lymph nodes, all ≤6 cm - **N2c:** Metastasis in bilateral or contralateral lymph nodes, all ≤6 cm - **N3a:** Metastasis in a lymph node >6 cm - **N3b:** Metastasis in multiple ipsilateral, bilateral, or contralateral nodes, any >6 cm This patient has **ipsilateral level I lymph node involvement** (firm, palpable), consistent with **N1**. ### Stage Grouping (TNM 8) | Stage | T | N | M | |-------|---|---|---| | I | T1 | N0 | M0 | | II | T2 | N0 | M0 | | III | T1–T2 | N1 | M0 OR T3 | N0 | M0 | | IVA | T4a | Any N | M0 OR Any T | N2–N3 | M0 | | IVB | T4b | Any N | M0 | | IVC | Any T | Any N | M1 | **Diagnosis: T2N1M0 = Stage III** **High-Yield:** The presence of any nodal metastasis (N1 or higher) automatically upgrades oral cavity carcinoma to at least Stage III, even if the primary tumour is small (T1 or T2). **Clinical Pearl:** Betel quid chewing is a major risk factor for oral cavity carcinoma in South Asia, particularly in India. The combination of tobacco, areca nut, and slaked lime creates a carcinogenic environment. Patients often present late because ulcers are attributed to poor oral hygiene or minor trauma. **Mnemonic: DOTS** — **D**epth of invasion, **O**ccurrence (size), **T**umour extent, **S**taging nodal involvement. Always assess DOI in oral cancers as it is a critical prognostic factor.