Mouth Tumors (Oral Cavity Cancer and Benign Oral Neoplasms): Diagnosis and Treatment — Overview, Diagnosis & Treatment Options | MyMedicPlus

Mouth (oral cavity) tumors encompass a spectrum from benign neoplasms to malignant carcinomas. Oral cavity squamous cell carcinoma (OC-SCC) accounts for over 90% of malignant oral tumors and is the sixth most common cancer globally, with approximately 380,000 new cases and 180,000 deaths per year (GLOBOCAN 2020). The oral cavity is anatomically defined as the region from the lips to the junction of the hard and soft palates and circumvallate papillae — encompassing the lip, anterior tongue (oral tongue, anterior two-thirds), floor of mouth, hard palate, buccal mucosa, upper and lower gingiva, and retromolar trigone. OC-SCC is predominantly driven by tobacco and alcohol — unlike the HPV-associated oropharyngeal cancer epidemic, OC-SCC remains largely tobacco-associated, with betel nut use a major risk factor in South and Southeast Asia. Benign oral tumors — fibromas, papillomas, pyogenic granulomas, peripheral giant cell granulomas, and pleomorphic adenoma of minor salivary glands — are common incidental findings managed by excision. Pre-malignant lesions — leukoplakia and erythroplakia — require surveillance and biopsy to exclude dysplasia or carcinoma in situ.

Tobacco use in all forms — cigarettes, cigars, pipe, cigar, bidi, khaini, gutka (smokeless tobacco), and betel quid with tobacco — is the dominant risk factor for OC-SCC. Risk is dose-dependent and synergistic with alcohol. Heavy alcohol consumption (>4 units/day) independently doubles risk and acts multiplicatively with tobacco — combined use confers a 30-fold increased risk. Betel nut (areca nut) chewing — common in India, Papua New Guinea, Southeast Asia, and the Pacific islands — is an independent carcinogen classified as Group 1 by IARC; associated oral submucous fibrosis (a pre-malignant condition) markedly elevates risk. Chronic mechanical trauma (ill-fitting dentures, sharp teeth) is associated with lateral tongue SCC in the absence of other risk factors — particularly in elderly patients. HPV infection plays a minor role in oral cavity SCC (as opposed to oropharyngeal SCC), contributing to 5–10% of cases. Solar radiation (UV) causes carcinoma of the vermilion border of the lip. Lichen planus — particularly the erosive form — has a malignant transformation rate of 1–5%. Immunosuppression (post-transplant, HIV) elevates risk. Fanconi's anemia and dyskeratosis congenita are genetic cancer predisposition syndromes.

OC-SCC classically presents as a non-healing mucosal ulcer with indurated (hard) raised edges — endophytic (ulcerative) or exophytic (proliferative) growth. A white patch (leukoplakia) or red patch (erythroplakia) on oral mucosa that cannot be wiped off and persists beyond 2 weeks must be biopsied. Erythroplakia — a velvety red mucosal lesion — carries 20–30 times greater malignant transformation risk than leukoplakia. Pain is often absent in early cancer (a dangerous clinical feature leading to diagnostic delay) and develops as tumors infiltrate deeper structures or adjacent nerves. Tongue SCC causes tongue mobility restriction, dysarthria, and dysphagia as the extrinsic tongue muscles are invaded. Floor-of-mouth tumors cause trismus (restricted jaw opening) when the masseter or pterygoid muscles are involved. Cervical lymphadenopathy from regional metastases — ipsilateral levels I–III nodes — is found in 30–50% of oral SCC at presentation. Advanced disease causes bleeding, fetor, and odynophagia.

Incisional or punch biopsy of the suspicious oral lesion is the diagnostic gold standard; the lesion should not be excised before histological diagnosis in any case where malignancy is suspected. Histopathology confirms invasive SCC (vs. carcinoma in situ vs. severe dysplasia), grade, and depth of invasion (DOI) — a crucial AJCC 8th edition T-stage determinant for oral cavity SCC. Depth of invasion ≥5 mm elevates T classification regardless of tumor surface dimension (T staging for oral SCC uses the 'worst of' between tumor size and DOI). MRI of the primary site with gadolinium is mandatory for local staging — superior to CT for tongue, floor of mouth, and mandibular involvement. CT neck is standard for cervical lymph node assessment. PET-CT detects occult distant metastases and synchronous primaries. Orthopantomogram (OPG) dental X-ray and CT mandible evaluate mandibular cortical invasion (which determines whether marginal or segmental mandibulectomy is required). HPV/p16 testing is performed but results rarely alter OC-SCC management (as HPV-driven OC-SCC is rare). AJCC 8th edition T-staging for OC-SCC uniquely incorporates DOI as a staging determinant.

Surgery is the primary treatment modality for most OC-SCC. Primary tumor excision requires histologically confirmed margins of ≥5 mm (clear margin) — close margins (<1 mm) necessitate re-excision or adjuvant radiotherapy. Elective neck dissection — selective neck dissection of levels I–IV — is performed for all T2+ primaries (due to >20% occult nodal metastasis rate), and for T1 tumors with DOI ≥4 mm. Reconstruction after wide excision uses primary closure, local flaps (nasolabial, palatal), or free flaps (radial forearm free flap for tongue, fibula free flap for mandible reconstruction) to restore speech and swallowing function. Adjuvant radiation (60–66 Gy IMRT) is indicated for pT3–4 disease, multiple positive nodes, or perineural invasion. Adjuvant concurrent cisplatin-chemoradiation is given for extranodal extension or positive surgical margins — demonstrably improving locoregional control per RTOG 9501 and EORTC 22931 landmark trials. Definitive chemoradiation is reserved for unresectable or surgically unfit patients. Pembrolizumab + chemotherapy is first-line for recurrent/metastatic disease per KEYNOTE-048.

Prognosis for oral cavity squamous cell carcinoma is strongly stage-dependent. Stage I OC-SCC (T1N0M0) treated with surgery achieves 5-year survival of 85–95%; Stage II achieves 70–85%. Locally advanced disease (Stage III–IVA) with surgery and adjuvant chemoradiation achieves 5-year survival of 40–65%. Metastatic disease (Stage IVB/C) has a median overall survival of 12–14 months with pembrolizumab-based systemic therapy. The most important adverse prognostic factors for OC-SCC include positive or close surgical margins, extranodal extension of nodal metastases (the most powerful independent adverse factor, mandating adjuvant cisplatin-chemoradiation), multiple positive cervical nodes, perineural invasion, lymphovascular invasion, and depth of invasion ≥10 mm. Tongue SCC has a higher rate of occult nodal metastasis than other oral cavity sites, necessitating elective neck dissection even for T1 tumors with DOI ≥4 mm. Benign oral tumors (fibromas, papillomas, pleomorphic adenoma of minor salivary glands) are cured by excision with minimal recurrence risk for most types. Oral submucous fibrosis carries a 7–13% malignant transformation rate over 10 years. Leukoplakia with severe dysplasia has a malignant transformation rate of 15–30% and requires close specialist surveillance. Long-term survivors of oral cavity cancer require 3-monthly clinical examination and imaging for 2 years, then 6-monthly thereafter to 5 years, with lifelong dental and nutritional support after radiation.

Oral cavity cancer is largely preventable by addressing modifiable risk factors. Tobacco cessation — in all forms including smokeless tobacco — is the single most important intervention and markedly reduces OC-SCC risk after cessation. Alcohol reduction, particularly avoiding concurrent heavy tobacco and alcohol use, is a key preventive measure. Betel nut cessation is critical in endemic populations; government-level banning of gutka has reduced exposure in India. Routine dental examination — a unique opportunity for oral cancer screening — should include visual inspection of all oral mucosal surfaces; dentists and dental hygienists should be trained in recognizing pre-malignant and malignant lesions. Any leukoplakia or erythroplakia persisting beyond 2 weeks in a high-risk patient (tobacco user, alcohol user, age >40) should be biopsied. Oral submucous fibrosis — caused by betel nut chewing — requires regular monitoring and biopsy of suspicious areas. HPV vaccination is recommended as a general cancer prevention measure, though its impact on oral cavity SCC (as opposed to oropharyngeal SCC) is expected to be modest.

Consult a dentist or doctor urgently for: any oral ulcer, white patch, red patch, or swelling that does not heal within 3 weeks; unexplained tongue pain, numbness, or restricted movement; jaw pain or trismus; a painless neck lump; or unexplained loose teeth without dental disease. Urgent 2-week-wait referral to an oral and maxillofacial or head and neck surgeon is mandated by NICE NG12 for patients over 45 with unexplained oral mucosal lesions or cervical lymphadenopathy. Do not reassure patients that a non-healing oral ulcer is 'aphthous' without having it examined by a specialist, particularly in tobacco or alcohol users. Patients with oral submucous fibrosis, oral lichen planus, or prior head and neck cancer require regular specialist surveillance — every 3–6 months — for life.