What is the treatment protocol for salivary gland tumors as per National Comprehensive Cancer Network (NCCN) guidelines?

Treatment Protocol for Salivary Gland Tumors

Complete surgical excision is the cornerstone of treatment for salivary gland malignancies, with postoperative radiation therapy added based on specific high-risk pathologic features including positive margins, perineural invasion, lymph node metastases, high-grade histology, and T3-T4 tumors. 1

Preoperative Evaluation

Imaging Requirements

• Perform CT with IV contrast or MRI of the neck and primary site for all suspected salivary gland cancers 1
• Use CT with IV contrast specifically when bone involvement is suspected 1
• Obtain contrast-enhanced MRI with diffusion sequences extending to the skull base when perineural invasion or skull base involvement is a concern 1
• Consider PET/CT from skull base to mid-thighs for advanced-stage high-grade tumors (though evidence is weaker for routine use) 1

Tissue Diagnosis

• Obtain tissue biopsy via fine needle aspiration (FNAB) or core needle biopsy (CNB) to distinguish malignant from benign lesions 1
• Use CNB when FNAB is inadequate or the location precludes FNAB (e.g., deep minor salivary glands) 1
• Pathologists should report risk stratification with attention to high-grade features 1

Surgical Management

Primary Tumor Resection

• Perform open surgical excision for all histologically confirmed malignancies 1
• For major salivary gland tumors: complete excision of the entire gland 1
• For minor salivary gland tumors: wide radical resection 1
• Achieve negative margins ≥5 mm when possible 2

Facial Nerve Management

• Preserve the facial nerve whenever it is not directly infiltrated by tumor 2
• Resect involved facial nerve branches only when there is preoperative facial nerve impairment or intraoperative finding of nerve encasement/gross involvement 1
• Nerves should not be conserved at the expense of tumor clearance 1

Neck Management

• Perform elective neck treatment (not observation) for T3-T4 tumors and high-grade malignancies in clinically negative necks 1
• For parotid malignancies: ipsilateral selective neck dissection of levels 2-4 1
• For T2 high-grade tumors: routine ipsilateral neck dissection 1
• For cN1 disease: ipsilateral neck dissection of involved and at-risk levels, potentially extending to levels 1-5 1

Postoperative Radiation Therapy

Mandatory Indications (Strong Evidence)

Postoperative RT should be offered for: 1

• All resected adenoid cystic carcinomas (regardless of other features)
• High-grade tumors
• Positive surgical margins
• Perineural invasion
• Lymph node metastases
• Lymphatic or vascular invasion
• T3-T4 tumors

Additional Indications

• Close margins or intermediate-grade tumors (weaker recommendation) 1
• Stage II, III, and IV high-grade tumors 1
• Low-grade stage III and IV tumors 1
• Any macro- or microscopically incomplete resection 1

Radiation Technique

• Target the salivary gland surgical bed and appropriate nodal levels with high-dose radiation 1
• When perineural invasion is present, cover the associated nerve(s) with elective or intermediate dose extending to the skull base 1
• Offer elective neck irradiation for cN0 disease with T3-T4 cancers or high-grade malignancies 1
• Use standard fractionation with photons ± electrons 1
• Particle therapy (proton, neutron, carbon ion) may be used but has no proven superiority over photon/electron therapy 1

Systemic Therapy

Adjuvant Setting

• Do not routinely add concurrent chemotherapy to adjuvant radiotherapy outside of clinical trials (evidence quality is low) 1
• Do not routinely offer adjuvant endocrine or targeted therapy for AR or HER2-Neu expressing tumors outside clinical trials 1

Recurrent/Metastatic Disease

• For limited metastases (≤5 lesions) in adenoid cystic carcinoma or low-grade tumors with indolent biology: consider local ablative treatments (metastatectomy or stereotactic body radiation) to delay progression 1
• For progressive metastatic disease: consider cisplatin-based chemotherapy (response rate ~25% in adenoid cystic carcinoma, >45% overall in palliative setting) 3, 2
• Chemotherapy should only be used when disease is overtly progressing 2

Recurrent Locoregional Disease

• Without distant metastases: offer revision resection with appropriate reconstruction 1
• With distant metastases: consider palliative revision resection if metastatic disease is not rapidly progressive or imminently lethal 1
• Evaluate all patients undergoing revision surgery for potential adjuvant therapy 1

Inoperable Disease

• Offer definitive radiotherapy to patients who are not surgical candidates due to extent of disease or medical comorbidity 1
• The high-dose target should cover gross disease in the salivary gland and appropriate nodal levels 1
• Neutron therapy alone may be considered for inoperable tumors when available 1
• Do not routinely add concurrent chemotherapy to definitive radiotherapy outside clinical trials 1

Surveillance Protocol

Follow-up Schedule

• Perform clinical examination with decreasing frequency as time elapses from treatment completion 1
• Obtain baseline imaging (contrast CT or MRI, or PET/CT) at 3 months after completing all treatment 1
• Years 1-2: surveillance imaging of primary site and chest CT every 6-12 months 1
• Years 3-5: imaging directed by symptoms and physical findings; yearly imaging may be offered for high-grade histology or poor prognostic features 1
• Beyond 5 years: yearly examination for all patients; yearly chest CT may be offered for high-grade histology or poor prognostic features 1

Critical Pitfalls to Avoid

• Do not perform inadequate initial surgery followed by radiation as this approach is inferior to complete resection 1
• Do not base major surgical decisions (such as facial nerve resection) on indeterminate preoperative or intraoperative diagnoses alone 1
• Do not omit postoperative radiation for adenoid cystic carcinoma even with complete resection, as this histology requires adjuvant RT 1
• Do not use chemotherapy routinely in the adjuvant setting as evidence does not support benefit outside clinical trials 1