What is the treatment for squamous cell carcinoma of the parotid gland?

Treatment of Squamous Cell Carcinoma of the Parotid Gland

Surgery combined with adjuvant radiation therapy is the standard of care for squamous cell carcinoma of the parotid gland, with at least a superficial parotidectomy recommended for all cases. 1

Surgical Management

Primary Surgery

• Extent of Parotidectomy:
  • At minimum, superficial parotidectomy should be performed for all parotid squamous cell carcinomas 1
  • For advanced (T3-T4) or high-grade tumors, consider total or subtotal parotidectomy to address risk of intraparotid nodal metastases 1
  • Complete surgical resection with negative margins is essential for improved overall survival 1

Facial Nerve Management

• Decision algorithm for facial nerve:
  1. Preserve facial nerve when preoperative function is intact and a dissection plane can be created between tumor and nerve 1
  2. Resect involved facial nerve branches when:
     • Preoperative facial weakness is present
     • Branches are encased or grossly involved by confirmed malignancy 1

Neck Dissection

• Regional lymph node dissection is indicated for squamous cell carcinoma with nodal involvement 1
• For clinically positive nodes, comprehensive neck dissection is recommended 2
• For clinically negative neck with parotid involvement:
  • Supraomohyoid neck dissection including external jugular lymph nodes for anterolateral primary tumors 2
  • Include level V dissection for posterior primary tumors 2

Adjuvant Treatment

Radiation Therapy

• Postoperative radiation therapy is recommended for:
  • pT3-4 tumors
  • Positive surgical margins (R1/R2)
  • Perineural infiltration
  • Lymphatic infiltration
  • Multiple positive lymph nodes
  • Extracapsular extension 1

Chemoradiation

• Postoperative chemoradiation is indicated for:
  • R1 resection (microscopic positive margins)
  • Extracapsular rupture 1
• Standard concurrent chemotherapy: cisplatin 100 mg/m² on days 1,22, and 43 of RT 1
• For patients unfit for cisplatin, alternatives include:
  • Carboplatin combined with 5-FU
  • Cetuximab with RT
  • Hyperfractionated or accelerated RT without chemotherapy 1

Timing

• Postoperative RT or chemoradiation should start within 6-7 weeks after surgery 1

Advanced/Metastatic Disease

Systemic Therapy Options

• For PD-L1 expressing tumors (CPS ≥1):
  • Pembrolizumab plus platinum/5-FU (when rapid tumor shrinkage needed)
  • Pembrolizumab monotherapy 1
• For PD-L1 negative tumors:
  • Platinum/5-FU/cetuximab is standard therapy 1
• For recurrence after platinum therapy:
  • Nivolumab for patients who progress within 6 months of platinum therapy 1

Prognostic Factors

• Poor prognostic indicators include:
  • Tumor size >6 cm 3
  • Facial nerve involvement 3
  • Immunosuppression (significantly worse overall survival, cancer-specific survival, and progression-free survival) 4
  • Larger nodal size (predictive of locoregional control) 4

Treatment Outcomes

• Despite multimodality treatment, parotid SCC has moderate rates of recurrence 4
• Median survival for primary parotid SCC is approximately 24 months 5
• Five-year overall survival rates range from 44-64% in immunocompetent patients, but drop to 14-40% in immunosuppressed patients 4

Important Considerations

• Patients should be treated at high-volume facilities with multidisciplinary teams 1
• Single-modality treatment is insufficient for parotid SCC, which is typically aggressive and requires combination therapy 3
• Close monitoring for recurrence is essential, particularly in the first 2-3 years after treatment