2017 Section 7 Green Book

sponse. The lower the pretreatment SUV value, themore response

to chemotherapywas seen.

Ameta-analysis demonstrated that PET

is highly accurate for response monitoring or relapse detection af-

ter radiotherapy with or without chemotherapy in advanced head

and neck cancers. This study showed 94% sensitivity, 82% speci-

ficity, 75% positive predictive value, and 95% negative predictive

value for PET in detecting residual lesions.

Sjovall et al

evalu-

ated 82 patients with head and neck cancer (85% OPSCC) and re-

portedthatPET/CThasasensitivityandspecificityof100%and78%,

respectively, in detecting residual tumor after radiotherapy.

The other issue is the optimal timing to evaluate the treatment

responsewith PET. Although on one handwe shouldwait for radia-

tion therapy and chemotherapy to show their full effect and treat-

ment inflammation to decrease (8-10 weeks), on the other, we do

not want to wait too long to prevent tumor progression or missed

treatment opportunities. Sensitivity of PET in therapy assessment

is lowwhenperformed less than 10weeks after treatment, whereas

specificity seems not to be related to timing.

Most reports stud-

ied the capability of PET in treatment evaluation within 2 months

after therapy.

Kimet al

reported high negative predictive value

of PET on evaluation of radiotherapy after 1 month. However, PET

used later than 12 weeks after treatment can decrease the number

of diagnosticneckdissections needed.

Ingeneral, it seems that PET

is a good modality for therapy assessment of OPSCC approxi-

mately3monthsafterradiotherapyand/orchemotherapy(

Figure4

Role of PET in Recurrence Detection of OPSCC

Despite all advances in treatment methods (surgery, radiotherapy,

chemotherapy), the locoregional recurrence rate of HPV-negative

OPSCC remains high. Some articles claim that up to 24% of pa-

tients with advanced head and neck cancer developed locore-

gional recurrence.

Although most of the time when the recur-

rence is detected, it is advanced and has aggressive tumor

characteristics (eFigures 2 and 3 in the

Supplement )

, a recent study

by Fakhry et al

showed improved survival in patients with recur-

rent HPV-related OPSCC treated with salvage surgery. In recur-

rence detection, PET has a lower false-negative and false-positive

rate when compared with conventional imaging.

A meta-

analysis by Isles et al

showed that PET has a sensitivity and speci-

ficity of 94%and 82%, respectively, for detecting residual or recur-

rent head and neck cancer. In a study that compared PET/CT vs

whole-body MRI in detecting recurrence in oropharyngeal and hy-

popharyngeal SCC, PET/CT had higher accuracy.

Positron emis-

sion tomography was reported to be a powerful tool in early recur-

rence detection of OPSCC

(eFigure 4 in the

Supplement )

Role of PET in Prognosis of OPSCC

Some studies evaluated the role of PET in predicting prognosis of

OPSCC and showed that a negative PET/CT result after therapy is

associated with lower chance of recurrence and better prognosis.

Therefore, this subgroup of patients needs less frequent radiologic

surveillance. The effect of negative PET result ismore prominent in

HPV-positive patients and is a better predictor of survival than OP-

SCC stage for these patients.

Different studies evaluated the

relationship between PET parameters (SUV

max,

SUV

mean,

SUV

peak

TLG,MTV)andprognosticfactorssuchasdisease-freesurvival(DFS),

progression-free survival (PFS), overall survival (OS), and disease-

specific survival (DSS). Because of its observer-independent mea-

surement, SUV is a popular PET parameter used by multiple

scientists.

Some previous studies claimthat SUV

max

predicts head

andneckcanceroutcomeandhigherSUV

max

isassociatedwithworse

DFS.

Most of these studies evaluated tumors from various head

and neck sites, with different tumor characteristics, risk factors, and

different overall prognosis. However, several recent studies re-

ported that SUVhadpoor predictiveperformance for treatment out-

come andhadno independent relation toOSorDFS, especiallywhen

corrected for stage.

13,46

Overall, it should not be a valuable predic-

tive factor for prognosis.

3,46

Figure 4. Therapy Assessment

A, Axial fused positron emission tomography/computed tomography (PET/CT)

image of initial scan of a man in his 60s with a history of left tongue base

squamous cell carcinoma, which presented as a fludeoxyglucose-avid lesion

(standard uptake value, 9.99) (arrowhead) in PET/CT. The patient was treated

with chemoradiation (9 weeks cetuximab, 7000 cGy). B, Three months after

treatment, PET/CT scan showed good response with diffuse uptake suggestive

of postradiotherapy inflammation (diffuse uptake, standard uptake value, 6.74).

C, The 9-month follow-up PET/CT showed complete response without any

interval treatment.

Use of FDG-PET/CT in Oropharyngeal Squamous Cell Carcinoma

Review

Clinical Review & Education

jamaotolaryngology.com

(Reprinted)

JAMA Otolaryngology–Head & Neck Surgery

January 2016 Volume 142, Number 1