11: MAJOR SALIVARY GLAND TUMORS

Adam Ferro, MD, MS
Ana Kiess, MD, PhD

WORKUP

All Cases

Image  H&P including complete head and neck exam and cranial nerve exam

Image  Imaging—contrast-enhanced CT and MRI of neck

Image  Fine-needle aspiration (FNA) of primary tumor

Image  Dental and nutrition evaluations prior to radiation

Stages III to IV

Image  PET/CT or CT chest

Image  MRI of skull base if concern for perineural spread

TREATMENT RECOMMENDATIONS BY STAGE

Benign

Surgery. Consider adjuvant RT for recurrent multifocal pleomorphic adenoma.

cT1–T4a

Surgery → adjuvant treatment as indicated (see “Post-op” section)

Post-op pT1–T2

Consider adjuvant RT for int/high grade, adenoid cystic histology, tumor spillage, or perineural invasion (PNI)

Post-op pT3–T4

Adjuvant RT for int/high grade, adenoid cystic histology, close/positive margins, PNI, nodal metastases, or LVI

OR consider adjuvant chemoRT for positive margins or ECE

Gross residual disease T4b

Unresectable

Unfit for surgery

Definitive RT

OR chemoRT

OR palliation with chemo or RT

OR supportive care

M1

Palliation with chemo, RT, or surgery

OR supportive care

TECHNICAL CONSIDERATIONS

Simulation

Simulate supine with neck extended, immobilize with thermoplastic mask. Consider mouthpiece. Wire scars. Consider bolus for disease near skin. Intravenous (IV) contrast if no contraindications. Fuse pre-op imaging.

Dose Prescription

Definitive RT

Image  High-risk areas: 66 Gy in 30 to 33 fx or 70 Gy in 35 fx

Image  Intermediate-risk areas: 60 Gy in 30 fx, or 63 Gy in 35 fx

Image  Low-risk areas: 54 Gy in 30 fx, or 56 Gy in 35 fx

Adjuvant RT

Image  High-risk areas: 63 Gy in 30 fx or 66 Gy in 33 fx

Image  Intermediate-risk areas: 60 Gy in 30 fx

Image  Low-risk areas: 54 Gy in 30 fx

ChemoRT

Image  High-risk areas: 70 Gy in 35 fx

Image  Intermediate-risk areas: 63 Gy in 35 fx

Image  Low-risk areas: 56 Gy in 35 fx

Target Delineation

Definitive

Image  GTV = gross disease based on exam and imaging

Image  Clinical target volume (CTV) high risk = GTV + margin for subclinical disease (5–10 mm)

Image  CTV intermediate risk:

      Image  Parotid: entire parotid, facial nerve track if PNI, or adenoid cystic carcinoma

      Image  Submandibular: entire submandibular, lingual or hypoglossal nerve track if PNI, or adenoid cystic carcinoma

      Image  Neck: ipsilateral IB-V if node involvement

      Image  CTV low risk = ipsilateral IB-III if node negative (may omit neck in adenoid cystic or low-grade histologies)

      Image  PTV = CTV + 3- to 5-mm margin, depending on image guidance

Post-Op

Image  CTV high risk = areas of positive margins or ECE

Image  CTV intermediate risk:

      Image  Parotid: entire parotid bed, facial nerve track if PNI, or adenoid cystic carcinoma

      Image  Submandibular: entire submandibular bed, lingual or hypoglossal nerve track if PNI, or adenoid cystic carcinoma

      Image  Neck: ipsilateral IB-V if node involvement

      Image  Post-op areas

Image  CTV low risk = ipsilateral IB-III if node negative (may omit neck in ACC or low-grade histologies)

Image  PTV = CTV + 3- to 5-mm margin, depending on image guidance

Treatment Planning

Image  6-MV photons

Image  Intensity-modulated radiation therapy (IMRT) preferred, with image guidance if available

Image  Prefer starting post-op cases within 6-weeks postsurgery

FOLLOW UP

Posttreatment baseline imaging of head and neck within 6 months after adjuvant RT. If asymptomatic, H&P every 1 to 3 months for year 1, every 2 to 6 months for year 2, every 4 to 8 months for years 3 to 5, then annually. Thyroid screening every 6 to 12 months. Management of nutrition, dental, speech, swallow, hearing, and smoking cessation as indicated. Chest imaging as indicated for smoking history.

SELECTED STUDIES

UCSF Risk Factors (Chen, Int J Radiat Oncol Biol Phys 2007)

Retrospective study of 207 patients with major salivary carcinomas treated with surgery without post-op radiotherapy. Five- and 10-year local/regional control were 86% and 74%, respectively. Independent predictors of local/regional recurrence were pathologic lymph node metastasis, high grade, positive margins, and T3 to 4 disease. The presence of one negative prognostic factor decreased LRR control to 37% to 63% at 10 years.

NWHHT (Terhaard, Int J Radiat Oncol Biol Phys 2005)

Retrospective analysis of 498 patients treated with surgery and post-op RT or surgery alone. Post-op RT improved 10-year LC for patients with T3 to 4 tumors (84% vs. 18%), close margins (95% vs. 55%), incomplete resection (82% vs. 44%), bone invasion (86% vs. 54%), and perineural invasion (88% vs. 60%).

UCSF cN0 Series (Chen, Int J Radiat Oncol Biol Phys 2007)

Retrospective analysis of 251 patients with cN0 salivary gland carcinoma treated with surgery and adjuvant RT. 131 patients (52%) received elective nodal irradiation. Elective nodal irradiation reduced the 10-year nodal failure rate from 26% to 0%. No nodal failures in patients with adenoid cystic or acinic cell histology.

UF ACC Series (Mendenhall, Head Neck 2004)

Retrospective study of 101 patients with adenoid cystic carcinoma treated with RT ± surgery. The combined modality arm resulted in improved LC at 10-years (91% vs. 43%) and overall survival (OS) at 10 years (55% vs. 42%).

UCSF ACC Series (Chen, Int J Radiat Oncol Biol Phys 2006)

Retrospective study of 140 patients with adenoid cystic carcinoma treated with surgery ± RT. T4 disease, perineural invasion, omission of post-op radiation, and major nerve involvement were independent predictors of LR. Among patients treated with surgery and post-op radiation, dose lower than 60 Gy, T4 disease, and major nerve involvement were predictors of LR.