Update: May 2003

Tumours of the salivary glands, both major (parotid, submandibular and sublingual) and minor, comprise only a small minority (3%) of head and neck cancers (1). Of these, approximately 80% are classified as benign and 20% as malignant.

Pathology

Benign lesions include pleomorphic adenoma (mixed tumour), papillary cystadenoma lymphomatosum (Warthin's tumour), benign lymphoepithelial tumour (Godwin's tumour), oncocytoma, papilloma, and monomorphic tumours.

Malignant lesions include mucoepidermoid carcinoma (low and high grade), malignant mixed tumour, adenoid cystic carcinoma, acinic cell carcinoma, adenocarcinoma, SCC, oncocytic cell carcinoma, clear cell carcinoma, lymphoma, melanoma and metastatic lesions.

Presentation

Benign lesions are often present for many years with little change. A malignant lesion often presents as a rapidly growing mass. Facial weakness, skin involvement, pain, adenopathy and speed of growth suggest malignant disease (2).

Workup

This should include history and physical, basic lab work (CBC, electrolytes, BUN, creatinine, LFT's), and imaging (CT of head and neck, Panorex, CXR). FNA is indicated in some circumstances, especially when one suspects malignant disease, or the patient is not a good surgical risk (3).

Staging

AJCC staging using TNM system.

Prognostic Factors

• Stage

• Grade: all malignant tumours are divided into low or high risk, depending on grade.

  "low risk" = low grade = low grade mucoepidermoid, acinic and oncocytic cell
  "high risk"= high grade = high grade mucoepidermoid and all the rest.

• Adenoid cystic is subdivided histologically:
  • Tubular pattern: best prognosis
  • Cribriform pattern: intermediate prognosis
  • Solid pattern: worst prognosis

Management

Surgery: type of surgery depends on location, grade and adenopathy. For both benign and malignant lesions, en bloc surgery with margin and without spillage.

• Low grade: superficial parotidectomy, sparing 7th nerve.
• High grade, deeply invasive or nerve involvement: sacrifice nerve to get good resection and use sural nerve for grafting.

Radiotherapy: indications (4):

• Primary treatment: only when patient medically unfit or refusing surgery.
• Adjuvant treatment for both benign and malignant lesions:
  • Benign: recurrent disease, tumour spillage, narrow margin or enucleation.
  • Malignant: depends on risk:
    • Low grade, no radiation unless tumour spillage, positive margin, gross residual disease, recurrence.
    • High grade, all require treatment.

Outcomes

Benign:

• after narrow excision or enucleation, recurrence rate is 20% at 10-15 years without radiation, and 3% with radiation (5).

Malignant:

• for low grade, 10 % recurrence if well resected and 20% if partial resection or biopsy only.
• For high grade, 30-50% recurrence without radiotherapy, decreases to 10-15% with radiotherapy, but this is dependent on stage at diagnosis.

References:

1. DeVita, V.T., et al, Cancer, Principles & Practice of Oncology, 5th Edition, Vol. 1, 29(4), p 830.

2. Million, R.M, and Cassisi, N.J., Management of Head and Neck Cancer, A Multidisciplinary Approach, 2nd Edition, p 716.

3. DeVita, V.T., et al, Cancer, Principles & Practice of Oncology, 5th Edition, Vol. 1, 29(4), p 836.

4. DeVita, V.T., et al, Cancer, Principles & Practice of Oncology, 5th Edition, Vol. 1, 29(4), p 836.

5. Million, R.M., and Cassisi, N.J.,Management of Head and Neck Cancer, A Multidisciplinary Approach, 2nd Edition, p730.