Residency · Residency · Otolaryngology
Systemic Therapy in Head and Neck Cancer
Introduction
Systemic therapy plays an increasingly important role in the management of head and neck squamous cell carcinoma (HNSCC) and other head and neck malignancies. This includes cytotoxic chemotherapy, targeted therapy, and immunotherapy. The otolaryngologist must understand the indications, commonly used agents, mechanisms of action, and toxicity profiles to participate effectively in multidisciplinary cancer care.
Role of Systemic Therapy
Concurrent Chemoradiation
Standard of care for locally advanced HNSCC (Stage III-IVB). Chemotherapy acts as a radiosensitizer, enhancing radiation-induced tumor cell kill. Improves locoregional control and overall survival compared to radiation alone. Cisplatin is the standard concurrent agent: 100 mg/m2 every 3 weeks x 3 cycles during RT.
Adjuvant Chemoradiation (Post-Surgical)
Indicated for high-risk pathologic features after primary surgery: Positive surgical margins. Extranodal extension (ENE). Cisplatin 100 mg/m2 every 3 weeks concurrent with 60-66 Gy RT. Based on EORTC 22931 and RTOG 9501 trials.
Induction Chemotherapy
Given before definitive treatment (radiation or chemoradiation). Controversial; does not consistently improve overall survival over concurrent chemoradiation alone. TPF regimen (docetaxel, cisplatin, 5-fluorouracil): standard induction regimen when used. Potential role: organ preservation in laryngeal/hypopharyngeal cancer, rapid tumor debulking for impending airway obstruction.
Palliative Systemic Therapy
For recurrent or metastatic (R/M) HNSCC not amenable to curative-intent surgery or radiation. Goal: prolong survival, palliate symptoms, maintain quality of life.
Chemotherapy Agents
| Agent | Class | Mechanism | Key Toxicities |
|---|---|---|---|
| Cisplatin | Platinum alkylating | DNA cross-linking | Nephrotoxicity, ototoxicity, neuropathy, emesis |
| Carboplatin | Platinum alkylating | DNA cross-linking | Myelosuppression; less nephro/ototoxic |
| 5-Fluorouracil | Antimetabolite | Thymidylate synthase inhibition | Mucositis, diarrhea, myelosuppression |
| Docetaxel | Taxane | Microtubule stabilization | Neutropenia, neuropathy, alopecia |
| Methotrexate | Antimetabolite | DHFR inhibition | Low toxicity at palliative doses |
| Cetuximab | Anti-EGFR mAb | Blocks EGFR activation | Acneiform rash, infusion reactions |
| Pembrolizumab | Anti-PD-1 | Restores T-cell anti-tumor activity | irAEs (thyroiditis, pneumonitis, colitis) |
| Nivolumab | Anti-PD-1 | Restores T-cell anti-tumor activity | irAEs (similar to pembrolizumab) |
Cisplatin
Platinum-based alkylating agent: cross-links DNA, preventing replication. Cornerstone of HNSCC treatment. Toxicities: nephrotoxicity (requires aggressive hydration), ototoxicity (high-frequency SNHL), neurotoxicity (peripheral neuropathy), severe nausea/vomiting (highly emetogenic), myelosuppression. Carboplatin: alternative for patients who cannot tolerate cisplatin (less nephro/ototoxic but more myelosuppressive).
5-Fluorouracil (5-FU)
Antimetabolite: inhibits thymidylate synthase, disrupting DNA synthesis. Used in combination regimens (TPF induction, palliative settings). Toxicities: mucositis, diarrhea, myelosuppression, hand-foot syndrome. DPD deficiency: rare genetic condition causing severe, life-threatening toxicity; pretreatment testing recommended.
Docetaxel (Taxotere)
Taxane: stabilizes microtubules, preventing cell division. Part of the TPF induction regimen. Toxicities: myelosuppression (neutropenia), peripheral neuropathy, alopecia, fluid retention.
Methotrexate
Antimetabolite: inhibits dihydrofolate reductase. Used as single-agent palliative therapy for R/M HNSCC, Low toxicity profile; weekly dosing, Modest response rates (10-15%).
Targeted Therapy
Cetuximab (Erbitux)
Monoclonal antibody targeting EGFR (epidermal growth factor receptor). Binds the extracellular domain of EGFR, blocking ligand-mediated activation. Bonner trial: cetuximab + RT improved overall survival vs. RT alone in locally advanced HNSCC. Used as an alternative to cisplatin for patients who cannot tolerate platinum-based chemotherapy (renal insufficiency, hearing loss, neuropathy). Toxicities: acneiform rash (correlates with treatment response), infusion reactions, hypomagnesemia, interstitial lung disease (rare). Cetuximab + RT is inferior to cisplatin + RT in HPV-positive oropharyngeal cancer (RTOG 1016, De-ESCALaTE).
Other EGFR Inhibitors
Panitumumab: fully human anti-EGFR antibody; less infusion reactions than cetuximab. Afatinib: oral irreversible EGFR tyrosine kinase inhibitor; second-line setting.
Immunotherapy
Immune Checkpoint Inhibitors
Pembrolizumab (Keytruda): anti-PD-1 monoclonal antibody. KEYNOTE-048: pembrolizumab +/- chemotherapy is first-line standard for R/M HNSCC. Pembrolizumab monotherapy: for PD-L1 CPS >=1 tumors. Pembrolizumab + cisplatin/carboplatin + 5-FU: for all R/M HNSCC regardless of PD-L1 status. Nivolumab (Opdivo): anti-PD-1 monoclonal antibody. CheckMate 141: improved OS vs. standard chemotherapy in platinum-refractory R/M HNSCC. Second-line treatment after platinum failure.
Mechanism of Action
Tumor cells upregulate PD-L1 to evade immune surveillance. Anti-PD-1 antibodies block the PD-1/PD-L1 interaction, restoring T-cell anti-tumor activity. Immunotherapy can produce durable responses in a subset of patients.
Biomarkers
PD-L1 Combined Positive Score (CPS): percentage of PD-L1-positive cells (tumor + immune cells); higher CPS correlates with better response to pembrolizumab monotherapy. Tumor mutational burden (TMB): emerging biomarker; higher TMB may predict immunotherapy response. HPV status: HPV-positive tumors may respond differently; ongoing investigation.
Immune-Related Adverse Events (irAEs)
Thyroiditis/hypothyroidism: most common endocrine irAE; monitor TSH. Pneumonitis: cough, dyspnea; may be fatal if unrecognized. Colitis: diarrhea, abdominal pain. Hepatitis: elevated transaminases. Dermatitis: rash, pruritus. Rare but serious: myocarditis, nephritis, adrenal insufficiency, myasthenia gravis. Management: severity-based; mild (continue with monitoring), moderate (hold treatment, corticosteroids), severe (discontinue permanently, high-dose steroids, additional immunosuppression).
Special Populations
HPV-Positive Oropharyngeal Cancer
Generally better prognosis than HPV-negative disease. De-escalation trials (reduce treatment intensity) are ongoing. Cisplatin + RT remains standard; cetuximab + RT is inferior (RTOG 1016). Immunotherapy trials specifically in HPV-positive disease are active.
Nasopharyngeal Carcinoma
Gemcitabine + cisplatin induction followed by concurrent chemoradiation is standard for advanced disease. Checkpoint inhibitors show promising activity in R/M nasopharyngeal carcinoma.
Salivary Gland Cancers
Limited role for conventional chemotherapy. Androgen receptor-positive salivary duct carcinoma: androgen deprivation therapy (leuprolide + bicalutamide). HER2-positive tumors: trastuzumab-based therapy. NTRK fusion-positive tumors: larotrectinib or entrectinib (tumor-agnostic approval).
Otolaryngologist's Role in Systemic Therapy
Pre-treatment assessment: baseline audiogram, dental evaluation, airway evaluation, PEG placement if needed. Monitoring during treatment: hearing changes, swallowing function, airway patency. Post-treatment surveillance: clinical examination, imaging, management of late effects. Multidisciplinary tumor board participation: essential for treatment planning.
Key Clinical Pearls
Cisplatin remains the standard concurrent chemotherapy agent for locally advanced HNSCC; obtain baseline audiometry and renal function before treatment. Cetuximab + RT is not equivalent to cisplatin + RT in HPV-positive oropharyngeal cancer — do not substitute without justification. Pembrolizumab is now first-line for recurrent/metastatic HNSCC — PD-L1 CPS testing is essential for treatment selection. Monitor for immune-related adverse events during checkpoint inhibitor therapy — early recognition prevents life-threatening complications. The otolaryngologist should actively participate in multidisciplinary tumor boards and understand the toxicity profiles of systemic agents to manage treatment-related complications.
References
- Vermorken JB, Mesia R, Rivera F, et al. Platinum-based chemotherapy plus cetuximab in head and neck cancer (EXTREME trial). N Engl J Med. 2008;359(11):1116-1127.
- Burtness B, Harrington KJ, Greil R, et al. Pembrolizumab alone or with chemotherapy versus cetuximab with chemotherapy for recurrent or metastatic squamous cell carcinoma of the head and neck (KEYNOTE-048). Lancet. 2019;394(10212):1915-1928.
- Bernier J, Domenge C, Ozsahin M, et al. Postoperative irradiation with or without concomitant chemotherapy for locally advanced head and neck cancer. N Engl J Med. 2004;350(19):1945-1952.
- Gillison ML, Trotti AM, Harris J, et al. Radiotherapy plus cetuximab or cisplatin in human papillomavirus-positive oropharyngeal cancer (NRG Oncology RTOG 1016). Lancet. 2019;393(10166):40-50.