Head and Neck Oncologic Surgery
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Direct answer
Oral cavity squamous carcinoma is the commonest cancer in Indian men across most population-based registries, fuelled by betel quid, gutkha and tobacco, and its surgery turns on depth of invasion rather than surface diameter. AJCC 8 made a 2 cm tumour with 6 mm depth a T2 while a 3 cm lesion with 4 mm depth stays lower — DOI crosses 5 mm and 10 mm to define T2 and T3, and above roughly 3–4 mm it triggers elective neck dissection in the clinically N0 neck. Margins aim for a centimetre of healthy tissue with 5 mm as the "close" threshold, and positive margins or extracapsular nodal spread commit the patient to post-operative cisplatin chemoradiation. Reconstruction ranges from the pectoralis major myocutaneous flap — still the Indian workhorse — to radial forearm, anterolateral thigh and fibula free flaps.
What you must remember
- DOI into T-stage (AJCC 8): T1 ≤2 cm and ≤5 mm; T2 = ≤2 cm with DOI >5 mm, or 2–4 cm with DOI ≤10 mm; T3 >4 cm or DOI >10 mm; T4 invades adjacent structures. Measure depth, not surface.
- Elective neck dissection in cN0 oral cancer is offered once DOI exceeds about 3–4 mm; for well-lateralised tumours this means levels I–III (extended to IV for oral tongue).
- Margins: 1 cm of clinically normal tissue is the target; a margin under 5 mm is "close" and, like a positive margin, drives adjuvant therapy decisions.
- Neck dissection vocabulary: selective (chosen levels), modified radical (levels I–V preserving internal jugular vein, sternomastoid or accessory nerve), radical (sacrificing all three — shoulder syndrome follows accessory loss).
- Adjuvant chemoradiation indications: positive margins and extracapsular extension (the EORTC 22931/RTOG 9501 merged teaching); radiation alone for multiple nodes, perineural or lymphovascular invasion.
- Flap ladder: pectoralis major myocutaneous for bulk and reliability without microsurgery; radial forearm free flap for tongue and floor of mouth; fibula free flap for mandibular segment; anterolateral thigh for large soft-tissue defects.
- Mandible: marginal (rim) resection for cortical proximity without invasion, segmental resection for bone involvement.
- Buccal mucosa is the Indian index site — betel-quid side, aggressive biology with skin involvement, and associated oral submucous fibrosis, a potentially malignant disorder of areca nut users.
A typical exam case: the buccal mucosa ulcer
A 55-year-old man with two decades of gutkha use has a 3 cm ulcer of the right buccal mucosa, biopsy-proven squamous carcinoma, DOI 8 mm, and a clinically N0 neck. Surgery is composite: peroral wide excision with 1.5 cm margins, marginal mandibulectomy for cortical proximity (segmental had bone invasion been shown on imaging), and elective ipsilateral selective neck dissection of levels I–III because depth exceeds 3 mm. A through-and-through cheek defect is reconstructed with a pectoralis major myocutaneous flap, or a folded anterolateral thigh flap where microsurgery is favoured. Histology returns margins clear at 6 mm, two positive level II nodes, and extracapsular extension — so he goes to post-operative cisplatin chemoradiotherapy, not radiation alone. Had margins been involved, re-excision would be weighed against boosting the radiation dose. The viva tests each branch point: why neck dissection (depth), why marginal not segmental mandible (cortical relation), why chemotherapy added (extracapsular spread).
How the examiner frames it
The classic traps are measuring the ulcer's diameter and ignoring depth; equating a "modified radical" with a selective dissection; and stopping the adjuvant conversation at node count while missing extracapsular extension, the one indication that mandates concurrent cisplatin. Indian examinations add two favourites: oral submucous fibrosis as a premalignant condition of areca nut chewers (fibrous bands, burning, trismus — counsel and survey), and the field-cancerisation concept that makes every follow-up visit a screening examination of the whole upper aero-digestive tract in continuing tobacco users.
Frequently asked questions
How does depth of invasion alter T-staging in oral cavity cancer?
AJCC 8 uses DOI cut-offs of 5 mm and 10 mm: a small tumour deeper than 5 mm becomes T2, and DOI beyond 10 mm is T3 even under 4 cm surface diameter.
Which levels are dissected in a clinically N0 oral cavity cancer?
Levels I–III for most sites, extended to level IV for oral tongue primaries; sentinel node biopsy is an alternative in small anterior tongue tumours in experienced centres.
What triggers post-operative chemoradiation rather than radiation alone?
Positive margins and extracapsular nodal extension — both mandate concurrent cisplatin; multiple nodes or perineural and lymphovascular invasion warrant radiation alone.
Which flap reconstructs which defect?
Pectoralis major myocutaneous flap for bulk and reliability; radial forearm free flap for tongue and floor of mouth; fibula osteocutaneous flap for mandibular segment; anterolateral thigh for large composite defects.
When is segmental rather than marginal mandibulectomy done?
Marginal (rim) resection suits cortical proximity or superficial disease; segmental resection is required for demonstrable bone invasion, gross dentulous-sector involvement, or prior radiotherapy.
What is oral submucous fibrosis and why does it matter?
Chronic, progressive fibrosing disorder of areca nut and gutkha chewers causing blanched mucosa, fibrous bands and trismus; a potentially malignant disorder requiring cessation counselling and surveillance.