Adjuvant Radiotherapy for Oral Tongue Cancer: Pearls and Pitfalls

Adjuvant Radiotherapy for Oral Tongue Cancer:
Pearls and Pitfalls of Treatment Planning
Jennifer L. Harper, MD
Associate Professor
Department of Radiation Oncology
Medical University of South Carolina
August 01, 2014
Why this Topic?
• 1. Common Clinic Challenges
• 2. Recent Literature to Guide IMRT
Treatment Planning for Oral Tongue
Cancer
Overview
• Oral tongue anatomy and patterns of regional
nodal metastasis
• Assessing risk for occult nodal disease
• IMRT treatment planning (selective targeting)
• Oncologic outcomes using IMRT
Anatomy of Oral Tongue
Lips
Hard Palate
FOM
Buccal
Mucosa
ACS US CANCER STATISTICS 2014
Site
Incidence
Deaths
Oral
Cavity
28,030
5,850
Tongue
13,590
2,150
Alveolus
Oral
Tongue
RMT
(48%)
Mukherji et al Neurographics 2003
Lymphatic Drainage of Oral Tongue
Levels
I,II, III
Level IV
Mukherji Radiology 1997
Surgical Management of cN0 Neck
Supraomohyoid Selective Neck Dissection
Indication for Postoperative
Radiotherapy
• Primary site
– T3 T4
– PNI, LVI, Close or Positive Margin
• Neck
– Multiple Positive Nodes
– Extracapsular Extension
• Elective treatment of the cN0
– Risk based
Assessing Risk of Occult Nodal
Metastasis for T1/T2 Oral Tongue
Cancer
Spiro et al Am J Surg 1986
Assessing Risk of Occult Nodal Metastasis
Reference
Spiro Am J Surg 1986
Brown Cancer 1989
Fakih Am J Surg 1989
Kurokawa Head Neck 2002
Lim Clin Cancer Res 2004
Threshold Ranges:
1.5 to 10 mm
Byers Head Neck 1998
Sparano Head Neck Surg 2004
Alkureishi Laryngoscope 2008
Fukano Head Neck 1997
Hosal Eur Arch Otorhino 1998
Kane EJSO 2006
O-charoenrat Oral Oncol 2003
Yuen Am J Surg 2000
Yuen Head Neck 2002
Shintani Oncology 1997
Why the confusion?
Challenges to Accurate Measurement
Exophytic
“tumor
thickness”
Ulcerated
“depth of
invasion”
Endophytic
“depth of
invasion”
AJCC staging Manual 7th edition
Why the confusion?
Challenges to Accurate Measurement
• Extensive hyperkeratosis that make it difficult
to determine where to begin measuring from
surface
• Peritumoral inflammation can make it difficult
to determine the invasive front of the tumor
• Formalin fixation can shrink the specimen
resulting in an artifactually smaller
measurement
Chandler et al Head and Neck Pathology 2011
Is There a Better Metric?
Superficial Muscle Invasion
Keratin Layer
Tumor
Superficial
Muscle
Chandler et al Head and Neck Pathology 2011
Superficial Muscle Invasion
Predictor of Occult Nodal Disease
• pT1 cN0 Oral Tongue SCC
– N=61
– Negative margins
– At least 2 yrs of follow up
– Compared the PPV of 3mm DOI vs muscle invasion
Chandler et al Head and Neck Pathology 2011
cN0 Neck Over-treat or Under-treat ?
• 4 Randomized Trials
• 283 patients
• Studies spanned 4 decades (19662004)
Fasunla et al Oral Oncol 2011
Meta-analysis Results
Elective Neck Dissection Decreases
Disease Specific Death
Fasunla et al Oral Oncol 2011
Take Home
• Early Stage cN0 Oral Tongue Consider the
Neck
– Radiographic staging alone is not adequate for
staging the neck
– cN0: pathologic factors should be used to direct
neck management (DOI, Tumor Thickness, Muscle
Invasion)
– Address the cN0 with Surgery or Radiation if the
risk of occult disease is >20%
Radiation Therapy
Treatment Planning
Oral Tongue Cancer Case:
• 65 yo male presenting with 4cm left lateral oral
tongue SCC and palpable nodes in the left Level 1B
and level 2 (cT2 cN2b cM0)
• s/p partial glossectomy and left selective neck
dissection (level 1-4)
• Path: 4cm SCC primary with PNI, all margins >1cm.
Neck-5 nodes positive (levels 1-2) no ECE
• pT2 pN2b cM0
Radiation Therapy Treatment Planning:
Historical Perspective
44Gy
56Gy
e-
60Gy
Ang and Garden Radiotherapy for Head and Neck Cancers 2002
Radiation Therapy Treatment Planning:
Historical Perspective
WE COULDN’T MISS !
Treatment Planning in the IMRT Era
• “Dose Painting”
56Gy
60Gy
Damast et al Head and Neck 2012
Treatment Planning in the IMRT Era
• 22 yo female presented with a R lateral oral
tongue SCC
• s/p R Hemiglossectomy and R selective neck
dissection
• Path: 2.1 cm SCC, thickness 7mm, +superficial
muscle invasion, +PNI, +LVI. Neck Level II 1/6+
nodes +ECE, Level I and Level III were negative
• pT2 pN1 cM0
Damast et al Head and Neck 2012
Treatment Planning in the IMRT Era
• Postoperative RT and Erbitux
• IMRT to primary site and upper right neck
Damast et al Head and Neck 2012
Treatment Planning in the IMRT Era
• Follow up imaging 3 months post treatment
•
•
•
•
180 consecutive pt OCSS
sp Surg IMRT +/- Chemo (2005-2010)
Report of 2 yr OS, DFS and LRR
Analyzed the patterns of failure
– LRR were spatially localized in relation to
dosimetric plans
Chan Oral Oncol 2013
Demographics
Treatment Details
Neck Nodal Targeting
Bilateral Necks
65%
Unilateral Neck
25%
Primary Site Only
10%
Refining Site of Failure
• In-field
> 95%Vrec was within the 95% isodose line
• Marginal
20%-95%Vrec was within the 95% isodose line
• Out of Field
<20%Vrec was within the 95% isodose line
Results: Patterns of LRR
Patterns of LR Recurrence
In-field
68%
Marginal
Out of
Field
19%
13%
N=26
N=7
N=5
32% of
recurrences
Contralateral Neck Failures in pN2b
High Level II/ Skull Base isp to + nodes
Intentionally spared regions near parotid isp
to + nodes
Results:
2yr OS
Results:
Chan et al Oral Oncol 2013
Take Home Pearls
• Bilateral neck irradiation in patient with pN2b
disease. (Some experts recommend for all oral
tongue)
• Include high Level II (up to jugular foramen) in the
presence of nodal involvement
• Don’t compromise CTV coverage at the level of
parotid on involved neck
• Ensure dosimetric coverage to Level I
• Primary target volume should include entire tongue
and flap