Lip and Oral Cavity Cancer: Causes, Symptoms, Diagnosis and Treatment — Overview, Diagnosis & Treatment Options | MyMedicPlus

Lip and oral cavity cancer is squamous cell carcinoma (SCC in over 90% of cases) arising from the mucosal lining of the oral cavity — which encompasses the lips, buccal mucosa, upper and lower gum (gingiva), floor of the mouth, hard palate, retromolar trigone, and the mobile oral tongue (anterior two-thirds). Approximately 54,000 new US cases of oral cavity and pharyngeal cancer are diagnosed annually, with oral cavity cancer accounting for approximately half. The mobile oral tongue is the most common subsite in Western nations; buccal mucosa SCC predominates in South and Southeast Asia due to widespread betel quid and tobacco chewing. Oral cavity SCC is biologically distinct from oropharyngeal SCC: it is predominantly HPV-negative, strongly tobacco- and alcohol-associated, and requires primary surgical resection as the preferred treatment modality (unlike oropharyngeal cancer, which is amenable to chemoradiation). Tobacco-associated leukoplakia and erythroplakia are recognized premalignant precursor lesions. The AJCC 8th edition staging system (2017) incorporated depth of invasion as a staging criterion for oral tongue cancer, reflecting the strong correlation between DOI greater than 4 mm and occult cervical nodal metastasis.

Tobacco smoking is the primary risk factor for oral cavity SCC in Western countries, with a clear dose-response relationship. Smokeless tobacco (chewing tobacco, snuff) causes specific patterns: buccal and labial mucosal cancers at the site of tobacco placement. Betel quid (areca nut with slaked lime, with or without tobacco) chewing — a practice widespread in South Asia, Southeast Asia, and parts of the Pacific — is the dominant risk factor for buccal mucosa carcinoma and accounts for the high incidence in India, Pakistan, and Taiwan. Heavy alcohol consumption acts synergistically with tobacco, multiplying risk by up to 30-fold compared to non-users of both. Poor oral hygiene, ill-fitting dental prostheses causing chronic mucosal irritation, and nutritional deficiencies (iron deficiency in Plummer-Vinson syndrome) contribute modestly to risk. Lip cancer specifically has an additional risk factor of cumulative UV radiation exposure, particularly in fair-skinned outdoor workers. HPV contributes to a minority (less than 15%) of oral cavity SCCs, without the dramatic prognostic benefit seen in HPV-associated oropharyngeal cancer.

Oral cavity SCC typically presents as a persistent ulcer, white patch (leukoplakia), red patch (erythroplakia), or exophytic (outwardly growing) mass in the oral cavity that persists beyond 3 weeks without healing. Tongue cancers cause tongue pain (glossodynia), particularly with eating spicy foods, or otalgia (referred ear pain via the lingual branch of the trigeminal nerve). Tongue fixation from deep muscle invasion causes speech difficulties and restricted tongue mobility. Floor-of-mouth cancers may cause submandibular swelling from sublingual gland compression. Mandibular invasion by gingival tumors produces dental pain, tooth mobility, and numbness along the distribution of the inferior alveolar nerve (mental nerve). A painless neck mass from cervical lymph node metastasis may be the presenting complaint, particularly for tongue and floor-of-mouth cancers with occult primary lesions. Advanced disease causes trismus (inability to fully open the mouth) from pterygoid muscle invasion, weight loss from dysphagia, and halitosis from tumor necrosis.

Clinical examination of the entire oral cavity under adequate lighting, with palpation of all mucosal surfaces including the floor of the mouth and tongue, is the initial diagnostic step. Biopsy of suspicious lesions is mandatory; incisional biopsy or punch biopsy provides histological diagnosis. CT of the neck and chest with IV contrast is the primary staging imaging, assessing tumor extent, mandibular cortical invasion (crucial for planning composite resection vs. marginal mandibulectomy), cervical nodal disease, and pulmonary metastases. MRI of the primary is superior for assessing DOI, tongue muscle invasion, perineural invasion along the inferior alveolar nerve, and floor-of-mouth extent. Panoramic dental radiograph (OPG) assesses mandibular cortical integrity. PET-CT identifies occult distant metastases. AJCC 8th edition TNM staging for oral cavity: T1 (tumor 2 cm or less, DOI 5 mm or less), T2 (2-4 cm or DOI greater than 5-10 mm), T3 (greater than 4 cm or DOI greater than 10 mm), T4a (moderately advanced: adjacent structures, cortical bone, tongue extrinsic muscles, floor of mouth skin, maxillary sinus), T4b (very advanced: masticator space, pterygoid plates, skull base, carotid artery). HPV testing and p16 IHC are performed to exclude misclassified oropharyngeal carcinoma.

Surgical resection is the primary treatment for oral cavity SCC, preferred over radiation-first approaches because it allows pathological staging, margin assessment, and avoidance of late radiation toxicity (osteoradionecrosis, xerostomia). T1-T2 oral tongue SCC (DOI 2-4 mm or less): wide local excision with 1-cm clinical margins plus ipsilateral selective neck dissection (levels I-III); primary closure or skin graft reconstruction. T2-T4a oral cavity SCC with nodal disease: composite resection (marginal or segmental mandibulectomy plus soft tissue resection) plus bilateral selective neck dissection, followed by microvascular free flap reconstruction (radial forearm free flap for tongue, fibular osteocutaneous free flap for mandibular reconstruction, anterolateral thigh flap for large soft tissue defects). Postoperative adjuvant treatment: high-risk features (positive margins, extranodal extension) require concurrent postoperative chemoradiation with cisplatin 100 mg/m2 plus 60-66 Gy (EORTC 22931/RTOG 9501 trials: improved DFS and OS). Risk features without ENE/positive margins: postoperative radiation 60-66 Gy alone. Recurrent or metastatic disease: pembrolizumab plus platinum-5FU or pembrolizumab monotherapy (PD-L1 CPS 1 or greater) per KEYNOTE-048; cetuximab plus radiation for cisplatin-ineligible patients.

Five-year overall survival: Stage I oral cavity SCC approximately 80-85%; Stage II approximately 65-70%; Stage III approximately 50-60%; Stage IVA approximately 40-50%; Stage IVB-C less than 20%. Extranodal extension (ENE) of cervical nodal metastasis is the strongest pathological adverse prognostic factor, mandating adjuvant chemoradiation. DOI greater than 10 mm is associated with greater than 40% rate of occult nodal metastasis. Perineural invasion and lymphovascular invasion are independent poor prognostic features. Oral cavity SCC has a substantial rate of local recurrence (20-30%) and second primary cancers from tobacco field cancerization. The prognosis for Lip and Oral Cavity Cancer: Causes, Symptoms, Diagnosis and Treatment varies depending on severity at diagnosis, the patient's overall health, and how promptly treatment is initiated. With early diagnosis and appropriate management, many patients achieve good outcomes and maintain quality of life. Regular follow-up with healthcare providers is essential to monitor progress, adjust treatment as needed, and detect any complications early. Adherence to prescribed treatments and lifestyle modifications significantly improves long-term prognosis.

Tobacco cessation — stopping all forms including smoking, chewing tobacco, snuff, and betel quid — is the single most impactful primary prevention measure. Risk reduction begins within 5 years of cessation and approaches near-normal after 15-20 years. Alcohol reduction, particularly eliminating heavy drinking combined with tobacco use, removes the synergistic co-carcinogen. UV-protective lip balm (SPF 30 or greater) and sun-protective hats protect against UV-induced lip carcinoma in outdoor workers. Early detection through oral cavity self-examination monthly and annual dental/medical oral examination enables detection of premalignant lesions (leukoplakia, erythroplakia) before invasive cancer develops. Biopsy of any suspicious white or red mucosal patch is the standard approach; lesions with moderate or severe dysplasia require ablative treatment or close surveillance. The Indian oral health programs and Sri Lanka oral cancer screening initiatives have demonstrated mortality reduction from systematic visual oral examination in high-risk populations. Good oral hygiene and prompt replacement of ill-fitting dentures reduce chronic mucosal irritation.

Seek urgent dental or medical evaluation for any mouth ulcer, white patch, red patch, or lump that fails to heal or regress within 3 weeks. Most benign mouth ulcers resolve within 10-14 days; persistence beyond 3 weeks mandates biopsy. Tongue or gum pain not explained by dental pathology, particularly in a tobacco user or heavy alcohol drinker, should be assessed by an oral surgeon or ENT specialist. Difficulty moving the tongue, restricted mouth opening (trismus), or new dental looseness without apparent dental disease in a tobacco user require urgent oral cavity examination. A painless or slowly growing lump on the lip — particularly in a fair-skinned person with a history of outdoor work or chronic sun exposure — should be evaluated by dermatology or oral medicine. Any person with a known premalignant oral lesion (leukoplakia, erythroplakia) who notices a new ulcerated or indurated area within the lesion should contact their specialist immediately. Bloody saliva, unexplained foul breath, or pain radiating to the ear combined with oral symptoms warrants same-day or next-day oral maxillofacial or ENT evaluation.