BACKGROUND

What staging system is used for cancer of the ear?

The AJCC 7^th edition (2011) for nonmelanoma skin cancer staging system is used for ear cancer (refer to Chapter 84).

WORKUP/STAGING

What is the general workup for tumors of the inner ear?

Tumor of the inner ear workup: H&P, otoscopy, LN exam, CT/MRI, tissue Bx, and audiometry

What structures constitute the outer and inner components of the ear?

Outer ear: pinna (auricle), external auditory canal, tympanic membrane, and middle ear

Inner ear: temporal bone (mastoid bone of bony and membranous labyrinth)

What is the lymphatic drainage of the ear?

The ear drains to the parotid, retroauricular, and cervical nodes.

What are the most common cancer histologies of the outer vs. the inner ear?

Pinna: basal cell carcinoma

Rest (canal, middle ear, mastoid): squamous cell carcinoma (SCC) (85%)

What % of pts with ear cancer present with nodal mets?

<15%

What anatomic site in addition to the ear has been added as a high-risk subsite per the 7^th AJCC edition?

Hair-bearing lip

Why is a tumor of the ear considered a high-risk feature per the 7^th edition AJCC?

Increased LR and potential for metastatic spread

What are all of the high-risk features for the primary tumor staging (T)?

DOI >2 mm, Clark level ≥IV, +PNI, poorly differentiated or undifferentiated, primary site ear or non-hair-bearing lip

TREATMENT/PROGNOSIS

What is the general Tx paradigm for a pt with ear cancer?

Surgery or definitive RT (surgery preferred for cartilage invasion)

What features of the primary tumor merit consideration of elective LN irradiation?

Elective LN irradiation is considered for large tumors (>4 cm) and deep invasion of underlying structures (i.e., cartilage).

How should SCC of the mastoid be treated?

SCC of the mastoid Tx: mastoidectomy or temporal bone resection → PORT

How are tumors of the pinna treated?

Electrons or orthovoltage RT (1-cm margin for <1-cm tumors; 2–3-cm margin for larger tumors)

How should tumors of the external auditory canal be treated?

Include in the Tx volume the entire external auditory canal and temporal bone with 2–3-cm margins, and include ipsi regional nodes (pre-/postauricular, level II); these tumors should be treated to 60–70 Gy.

How should the RT doses be modified based on tumor size?

Conventional fx of 1.8–2 Gy:

Small thin lesions <1.5 cm: 50 Gy

Larger tumors: 55 Gy

Min cartilage/bone involvement: 60 Gy

Cartilage/bone involvement: 66 Gy

When should higher-energy electrons be used for ear lesions?

Higher-energy electrons should be used for large, deep, unresectable tumors (to cover the deepest extent).

What simple technique can reduce heterogeneity and reduce inner dose in a pt being treated with electrons?

Per Morrison WH et al. (IJROBP 1995), place pt in true lat position, and use water bolus to account for inhomogeneity when treating external ear.

TOXICITY

What is the max dose allowed in order to minimize the likelihood of osteoradionecrosis?

Osteoradionecrosis can be minimized by keeping bone doses to <70 Gy (∼10% rate for doses >65 Gy).

What are some complications in the Tx of the ear with RT?

RT complications include osteo- or cartilage necrosis, hearing loss, chronic otitis, and xerostomia.

Data from Canadian series (Hayter C, IJROBP 1996; Silva P et al., IJROBP 2000) suggest what Tx feature was associated with increased necrosis risk?

Large fx size; to prevent necrosis, doses <4 Gy daily should be used.

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