Radiation Oncology · Supplementary · from Radiation Oncology

Case 2: Definitive Chemoradiation for Head and Neck Cancer

Patient Presentation

Demographics: 57-year-old male truck driver

Chief Complaint: "I've had a sore throat for 3 months and found a lump in my neck."

History of Present Illness: A 57-year-old male presents with a 3-month history of progressive sore throat, initially on the left side, now bilateral. He reports difficulty swallowing solid foods and has lost 7 kg over 3 months. Two weeks ago, he noticed a firm, non-tender lump in his left neck. He also reports referred pain to his left ear (otalgia) and a change in voice quality (muffled, "hot potato" voice). He denies hemoptysis, stridor, or trismus.

He was evaluated by his primary care physician, who referred him to an otolaryngologist. Flexible nasopharyngolaryngoscopy revealed a 3 cm exophytic mass arising from the left base of tongue extending to the left tonsillar fossa. Biopsy confirmed squamous cell carcinoma, p16-positive (HPV-associated). CT neck with contrast and PET/CT were performed for staging.

Given the stage and HPV-positive status, the multidisciplinary tumor board recommended definitive concurrent chemoradiation therapy with organ preservation, rather than primary surgery.

Past Medical History:

• Hypertension
• Gastroesophageal reflux disease
• No prior head and neck cancer
• No prior radiation exposure

Medications:

• Losartan 50 mg daily
• Omeprazole 40 mg daily

Social History:

• Truck driver (long-haul)
• Former smoker: 15 pack-years, quit 10 years ago
• Social alcohol: 4-6 beers per week
• Divorced, lives alone
• No illicit drug use

Family History:

• Father: lung cancer at age 72
• No family history of head and neck cancer

Physical Examination

• Vital Signs: BP 136/82 mmHg, HR 78 bpm, RR 14/min, Temp 37.0°C, SpO2 98% on room air, Weight 82 kg (down from 89 kg), Height 180 cm
• General: Thin male, appears fatigued, mild odynophagia when speaking
• HEENT:
• Oral cavity: Normal dentition (dental clearance obtained pre-RT), no trismus (interincisal distance 42 mm)
• Oropharynx: 3 cm exophytic, ulcerated mass arising from left base of tongue, crossing midline, extending to left tonsillar fossa; right tonsil appears normal
• Indirect laryngoscopy: Bilateral true vocal cord mobility normal
• Neck:
• Left level II: 3.5 cm firm, fixed, non-tender lymph node
• Left level III: 2.0 cm firm node
• Right neck: no palpable lymphadenopathy
• Cardiovascular: Regular rate and rhythm
• Lungs: Clear bilaterally
• Neurological: Cranial nerves II-XII intact, no hypoglossal weakness

Workup and Results

Laboratory Studies:

Pathology:

• Squamous cell carcinoma, non-keratinizing
• p16-positive by IHC (block positivity >70%)
• HPV-16 detected by in situ hybridization

Imaging/Additional Studies:

• CT Neck with contrast: 3.2 cm enhancing mass in left base of tongue crossing midline; left level II node 3.8 cm with central necrosis; left level III node 2.2 cm; no retropharyngeal nodes
• F-18 FDG PET/CT: Intensely FDG-avid primary tumor (SUVmax 18.2); FDG-avid left level II (SUVmax 12.4) and level III (SUVmax 8.8) nodes; no distant metastases; no FDG-avid contralateral nodes
• MRI Neck: Better soft tissue delineation; tumor extends to left glossotonsillar sulcus; no skull base invasion; no prevertebral fascia involvement
• Staging: T3N1M0 (AJCC 8th edition, p16-positive oropharyngeal), Stage I (p16+ staging)

Clinical Image

Diagram showing intensity-modulated radiation therapy (IMRT) treatment plan for oropharyngeal cancer with dose color wash demonstrating high-dose volume encompassing primary tumor and involved nodes, intermediate-dose volume covering at-risk nodal regions, and parotid gland sparing to reduce xerostomia. Source: Educational illustration.

Diagnosis

HPV-Positive (p16+) Squamous Cell Carcinoma of the Left Base of Tongue, T3N1M0, AJCC 8th Edition Stage I, Planned for Definitive Concurrent Chemoradiation

Key Diagnostic Criteria:

• Biopsy-confirmed squamous cell carcinoma with p16 positivity (HPV-associated)
• Primary tumor >4 cm (T3) involving left base of tongue crossing midline
• Ipsilateral single lymph node metastasis <6 cm (N1)
• No distant metastases on PET/CT
• p16-positive oropharyngeal SCC has a significantly better prognosis than HPV-negative disease (3-year OS >80%)

Treatment Plan

1. Radiation therapy prescription:

• High-risk CTV (primary tumor + involved nodes): 70 Gy in 35 fractions (2 Gy/fraction) over 7 weeks
• Intermediate-risk CTV (at-risk bilateral nodal levels II-IV, retropharyngeal nodes): 56 Gy in 35 fractions (1.6 Gy/fraction) simultaneously
• Low-risk CTV (bilateral level V, level IB): 54 Gy in 35 fractions (if indicated)

1. Technique: Volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB); daily CBCT for image guidance
2. Concurrent chemotherapy: Cisplatin 100 mg/m² IV on days 1, 22, and 43 of radiation (standard high-dose cisplatin regimen)
3. Pre-treatment preparation:

• Dental extraction of carious teeth (completed)
• Custom fluoride trays fabricated for daily fluoride application (lifelong for radiation caries prevention)
• Prophylactic PEG tube placement given tumor size and anticipated severe mucositis/dysphagia
• Baseline swallowing evaluation with speech-language pathology
• Begin prophylactic swallowing exercises (Mendelsohn maneuver, tongue base retraction)

1. OAR dose constraints:

• Parotid glands: Mean dose <26 Gy to at least one parotid (sparing to reduce xerostomia)
• Spinal cord: Max dose <45 Gy
• Brainstem: Max dose <54 Gy
• Mandible: Max dose <70 Gy
• Pharyngeal constrictors: Mean dose <50 Gy (reduce dysphagia)
• Larynx: Mean dose <40 Gy

1. Supportive care during treatment:

• Weekly oncology clinic visit for toxicity assessment and weight monitoring
• Aggressive oral care (salt/baking soda rinses, nystatin for candidiasis prophylaxis)
• Pain management escalation (viscous lidocaine to opioid analgesics as needed)
• IV hydration with cisplatin; monitor renal function, electrolytes, audiometry
• Nutritional support via PEG tube if oral intake <60% of caloric needs

1. Post-treatment response assessment: PET/CT at 12 weeks post-treatment completion; if complete metabolic response, surveillance; if residual PET-avid disease, consider neck dissection for nodal disease

Key Learning Points

• HPV-positive oropharyngeal squamous cell carcinoma is a distinct disease entity with significantly better prognosis than HPV-negative disease, leading to de-escalation trials aimed at reducing treatment toxicity while maintaining cure rates
• Intensity-modulated radiation therapy (IMRT) or VMAT enables precise dose sculpting that spares parotid glands, significantly reducing the incidence and severity of chronic xerostomia compared to older 3D-conformal techniques
• Concurrent cisplatin-based chemoradiation is the standard of care for locally advanced oropharyngeal cancer, with cisplatin providing a 6-8% absolute survival benefit as a radiosensitizer
• Acute toxicities of head and neck chemoradiation include mucositis (grade 3 in ~50% of patients), dysphagia, dermatitis, and myelosuppression; proactive supportive care and nutritional support are essential
• Prophylactic swallowing exercises during and after radiation reduce the risk of chronic dysphagia and pharyngeal stricture, a major quality-of-life concern for long-term survivors

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