Background

Question 1

What is the incidence of oropharyngeal cancer (OPC) in the United States?

Answer 1

∼36,000 cases/yr of OPC in the United States with 6,850 deaths (2013 data)

Question 2

How does the incidence of OPC compare to that of other H&N sites?

Answer 2

The incidence of OPC is increasing, whereas cancer of other H&N sites is decreasing.

Question 3

Is there a sex predilection for OPC?

Answer 3

Yes. Males are more commonly affected than females (3:1).

Question 4

What are the 4 subsites of the OPX?

Answer 4

Soft palate, tonsils, base of tongue (BOT), and pharyngeal wall

Question 5

From which subsite do most OPCs arise?

Answer 5

The tonsil (ant tonsil pillar and fossa) is the most common primary site.

Question 6

What are the borders of the OPX?

Answer 6

Anterior: oral tongue/circumvallate papillae

Superior: hard palate/soft palate junction

Inferior: valleculae

Posterior: pharyngeal wall

Lateral: tonsil

Question 7

What 3 structures make up the walls of the tonsillar fossa?

Answer 7

Walls of the tonsillar fossa:

Ant tonsillar pillar (palatoglossus muscle)
Post tonsillar pillar (palatopharyngeus muscle)
Inf glossotonsillar sulcus

Question 8

What are the 4 most important risk factors for the development of OPC?

Answer 8

Risk factors for developing OPC:

Smoking
Alcohol
HPV infection (up to 80% of cases now)
Betel nut consumption

Question 9

What is the 1st-echelon drainage region for most OPCs?

Answer 9

The 1st-echelon drainage site for most OPCs is the level II (upper jugulodigastric) nodes.

Question 10

Are skip mets common for OPC?

Answer 10

No. Skip mets are extremely rare in OPC (<1%).

Question 11

What are the 2 most common histologies encountered in the OPX? Rare histologies?

Answer 11

Most common histologies: squamous cell carcinoma (SCC) (90%), non-Hodgkin lymphoma (10% tonsil, 2% BOT)

Rare histologies: lymphoepithelioma, adenoid cystic carcinoma, plasmacytoma, melanoma, small cell carcinoma, mets

Question 12

What proportion of pts with OPC fail locoregionally vs. distantly?

Answer 12

1:1 proportion of locoregional:distant failures

Question 13

How prevalent is HPV infection in OPC?

Answer 13

Depending on the series, 40%–80% of OPCs are associated with HPV infection.

Question 14

Which HPV serotype is most commonly associated with OPC?

Answer 14

HPV 16 is the most common serotype in OPC (80%–90%).

Question 15

What is a surrogate marker of HPV infection in OPC that can be used as an indirect indication of HPV seropositivity?

Answer 15

The surrogate marker for HPV infection is p16 staining; E7 protein inactivates Rb, which upregulates p16.

Question 16

Which pt population is most likely to present with HPV-related OPC?

Answer 16

Nonsmokers and nondrinkers are most likely to have HPV+ SCC of the OPX.

Question 17

Do HPV+ or HPV– OPC pts have a better prognosis?

Answer 17

HPV+ OPC pts have a better prognosis. Data from RTOG 0129 (Ang KK et al., NEJM 2010) showed better 3-yr OS (82.4% vs. 57.1%) and risk of death (HR 0.42) for HPV+ pts. Smoking was an independent poor prognostic factor.

Question 18

What is the hypothesis behind why HPV+ OPC pts have a better prognosis?

Answer 18

HPV+ H&N cancers are usually in nonsmokers and nondrinkers, so p53 status is usually nonmutated; p53 mutation (which is common in non–HPV-related H&N cancers) predicts for a poor response to Tx.