Oropharyngeal Cancer - Early Stage

Summary:

Treatment options for early stage oropharyngeal cancers include:
1. Definitive Radiation alone 70 Gy in 35 fractions (preferred)
2. Definitive Radiation to 50 Gy then 20 - 30 Gy delivered via brachytherapy
3. Surgical resection with neck dissection +/- adjuvant chemoradiation or radiation as needed.

These patients can expect to do well, with good local control ~80 -100% and good overall survival 70-100% at 5 years

__________________

Early stage oropharyngeal cancers include T1N0 and T2N0 tumors.

Treatment options include:

1. Definitive radiation alone
   
2. Surgical resection with neck dissection +/- chemoradiation or radiation adjuvantly

Since the oropharynx is a central structure that plays a key role in phonation, speech and swallowing definitive radiation is the preferred treatment modality to maximize function after curative treatment. Surgery may be an option for small, accessible tumors that can be resected with adequate margins without compromising function.

There is a lack of Level I or even Level II evidence to definitively guide treatment. Data comes from single institution retrospective analyses from the 1980's demonstrating high rates of control. Some of the older data have worse outcomes, but keep in mind that this pre-dates 3D CRT never mind IMRT and newer treatment techniques.

5 yr LC:
T1N0 = 90-100%
T2N0 = 70-90%

5yr OS:
T1: 80-100%
T2: 70-90%

Definitive radiation can be delivered as EBRT alone or in combination with brachytherapy. A standard dose for EBRT alone is 70 Gy in 35 fractions. There is experience and retrospective data showing that adding brachytherapy after 50 Gy of EBRT has good local control rates. Altered fractionation, such as concomitant boost may be considered; however, the reasoning is based on extrapolation primarily from RTOG 90-03. This study showed improved local control, but the study population was locally advanced tumors, although some were T3N0's.

Special considerations:
Soft palate and pharyngeal cancers tend to drain bilaterally to the neck and retropharyngeal lymphatics.

Early stage tonsillar cancers drain unilaterally. Bilateral drainage in advanced cancers.

Treatment Planning
Plan by IMRT!

GTV = Gross tumor & suspicious LNs
CTV70 = GTV + 1 cm
CTV64 = CTV70 + LN areas at risk (usually regional LN and LN region above and below)
CTV56 = LN region considered to be at lower risk (adjacent to CTV60 LN groups)

PTV = CTV + 3 mm

ENT Anatomy - Pharynx Part I

The Pharynx is subdivided into three sites:
1. The Nasopharynx
2. The Oropharynx
3. The Hypopharynx





1. The Nasopharynx

The Nasopharynx is located posterior to the nasal cavity choanae (anterior border). It is bounded superiorly by the sphenoid sinus and inferiorly by the soft palate. The posterior wall overlies the base of skull including the clivus and atlas. The lateral walls are the nasopharyngeal mucosa. Located on the lateral walls is the Taurus Tubarius, which is the opening of the Eustachian Tube. Posterior to this is Rosenmueller's Fossa, which is a common site of origin for nasopharyngeal cancers. The roof of the nasopharynx is lined with adenoid lymphatics, which are a component of Waldeyer's ring.


The nasopharynx is innervated by the Glossopharyngeal Nerve (CN IX) and the Maxillary Nerve (CN V2).

Multiple foramen in this region act as potential points of entry for nasopharyngeal cancers. Notably the Foramen Lacerum, which allows entrance into the middle cranial fossa. Other foramen include Foramen Jugulare, Foramen Ovale, Foramen Spinosum, the Carotid Canals and the hypoglossal canals




2. The Oropharynx

The oropharynx is bounded superiorly by the soft palate and inferiorly by the superior aspect of the hyoid bone. The mucosa overlying the C2 and C3 verterbral bodies form the posterior wall. The anterior aspect consists of the anterior palatine pillar and the anterior edge of the soft palate.

The oropharynx consists of 4 subsites:
The soft palate, the tonsillar region, the base of tongue and the pharyngeal walls.

The soft palate includes the uvula. The tonsils are found between the anterior and posterior tonsillar pillars. The base of tongue encompasses the tongue found between the vallecula and the circumvallate papilla.


Lymphatic drainage of this region is primarily to the jugulodigastric lymph node or Level II lymph nodes. Pharyngeal walls are drained by the retropharyngeal. The retropharyngeal nodes consist of a medial and lateral component. The lateral component is also known as Rouviere Nodes. Drainage is primarily unilateral, unless a tumor invades midline structures where it may drain the bilateral cervical chains.

Innervation of this area is primarily via CN IX & X.


3. The Hypopharynx or Laryngopharynx

See next post...