Advanced Staging of Nasopharyngeal Carcinoma

in the AJCC 9th Edition: Implications for Radiologists

Introduction

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• Nasopharyngeal carcinoma (NPC) is a radiosensitive malignancy typically managed with chemoradiation, making imaging-based staging essential.
• The AJCC 9th Edition for NPC, released in 2024, continues to treat nasopharyngeal cancer as a distinct staging entity, now published as a site-specific monograph separate from other head and neck cancers.
• Radiologists are pivotal in NPC staging, as most criteria rely on MRI and CT interpretation rather than surgical pathology.
• This exhibit reviews the updated staging system with imaging examples and tips to enhance diagnostic accuracy and reporting consistency.

Objectives

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

1. Review recent updates to the AJCC 9th Edition staging system for nasopharyngeal carcinoma.
2. Recognize key imaging features relevant to T and N category staging.
3. Improve confidence in applying updated staging criteria to radiologic reporting.

Overview of Staging Updates

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• AJCC 9th Edition reflects advances in risk stratification and imaging-based staging of NPC.
• Key changes focus on refined definitions of T3 and N3 categories.
• Other categories remain largely consistent with the 8th Edition.

• No change in M category, but future editions may refine oligometastatic disease definitions.
• Imaging interpretation now directly influences staging more than ever.

T Category – Key Points

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• T staging in nasopharyngeal carcinoma is based on the anatomic extent of tumor spread.
• The major revision involves a clarified definition of T3 bone invasion.
• imaging evidence of definite bone invasion — not just sclerosis or abutment

T Category – Key Points

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• New clarification: Inferior orbital fissure (IOF) involvement is now explicitly categorized as T4.
• Cranial nerve involvement must be unequivocal (radiologic and/or clinical) to qualify as T4.

T Category – Staging Landmarks

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• T staging is based on the anatomic extent of tumor spread.
• Accurate identification of bone invasion, parapharyngeal extension, and cranial nerve involvement is essential.
• Both MRI and CT should be used complementarily to improve staging precision.

T Category – T2: Parapharyngeal Extension

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• The parapharyngeal space is a fat-filled space lateral to the superior pharyngeal constrictor muscle and medial to the medial pterygoid muscle.

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Imaging Tip:

• Loss of the fat plane between the tumor and parapharyngeal space
• Displacement or obliteration of the parapharyngeal fat pad
• Use T1WI without fat saturation to assess preserved fat planes
• Parapharyngeal extension = T2, regardless of involvement depth

T Category – T3: Unequivocal Bone Invasion

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• T3 requires unequivocal bone invasion of the skull base, cervical vertebrae, or paranasal sinuses.
• Imaging must show cortical destruction or marrow signal abnormality, not just contact or sclerosis.

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Imaging Tip:

• CT is preferred for cortical breach (d)
• MRI is sensitive for marrow infiltration (a,b)

T Category – T4: IOF Involvement

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• Inferior orbital fissure (IOF) is the junction between the orbit and pterygopalatine fossa.

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Imaging Tip:

• Use axial and coronal T1WI with contrast to evaluate tumor abutment or invasion of the IOF
• Loss of the bony cortex, soft tissue extension into or through the IOF, or fat infiltration = suggestive of IOF involvement
• Not be confused with pterygopalatine fossa or infratemporal fossa extension alone

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T Category – T4: Cranial Nerve Involvement

Introduction

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Overview

T Category

N Category

Tips for Report

Summary

References

• Involvement of cranial nerves, particularly CN V (V2/V3) and CN VI
• Only unequivocal perineural spread, either radiologic or clinical, qualifies

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Imaging Tip:

• Track tumor along foramina:
• Foramen rotundum (V2)
• Foramen ovale (V3)
• Dorello’s canal (CN VI)
• Look for nerve thickening, enhancement, or extension to Meckel’s cave, cavernous sinus
• Use contrast-enhanced T1WI with fat suppression

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Foramen ovale / Meckel's cave

Foramen rotundum

N Category – Key Points

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• N staging is determined by size, laterality, location, and now, presence of advanced extranodal extension (ENE).
• AJCC 9th Edition adds radiologic advanced ENE as a defining feature of N3 disease.
• Accurate assessment of ENE on imaging is essential for proper nodal staging.

N Category – Advanced ENE

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• Advanced ENE is defined as unequivocal radiologic evidence of tumor extension beyond the lymph node capsule.
• It must involve adjacent structures, such as:
• Skeletal muscle (e.g., sternocleidomastoid)
• Skin
• Neurovascular bundles
• Pathologic confirmation is not required — radiologic diagnosis alone is sufficient.
• The following features do not meet the criteria for advanced ENE
• Irregular or indistinct nodal margins
• Perinodal fat stranding
• Adjacent nodal matting / conglomeration
• Coalescent or matted nodes
• ENE of retropharyngeal lymph nodes (explicitly excluded)

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N Category – Advanced ENE

Introduction

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Overview

T Category

N Category

Tips for Report

Summary

References

Imaging Tip:

Direct invasion into the ipsilateral internal jugular vein, scalene muscle, and sternocleidomastoid muscle

Tips for Radiologic Reporting

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• Systematic search and structured reporting are essential for accurate AJCC 9th Edition staging in NPC.
• Begin at the primary site and evaluate tumor spread directionally, referencing key anatomic landmarks from the T category.
• Assess nodal involvement by size, laterality, level, and features of advanced extranodal extension (ENE).
• Align reporting with staging criteria by describing what structures are involved, not just the stage label.

Tips for Radiologic Reporting

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

• Reporting Check List for T/N Staging

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Staging Exercise

Introduction

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Overview

T Category

N Category

Tips for Report

Summary

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Case 1 (69/F)

Staging Exercise

Introduction

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Overview

T Category

N Category

Tips for Report

Summary

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Case 1 (69/F)

Staging Exercise

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

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Case 1 (69/F)

Staging Exercise

Introduction

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Overview

T Category

N Category

Tips for Report

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Case 1 (69/F)

Answer: T3

Staging Exercise

Introduction

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Overview

T Category

N Category

Tips for Report

Summary

References

Case 2 (74/M)

5.5cm

Staging Exercise

Introduction

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T Category

N Category

Tips for Report

Summary

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Case 2 (74/M)

Staging Exercise

Introduction

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T Category

N Category

Tips for Report

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Case 2 (74/M)

Staging Exercise

Introduction

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T Category

N Category

Tips for Report

Summary

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Case 2 (74/M)

Answer: T2N2

Staging Exercise

Introduction

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Overview

T Category

N Category

Tips for Report

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Case 3 (63/M)

Staging Exercise

Introduction

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Overview

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N Category

Tips for Report

Summary

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Case 3 (63/M)

Staging Exercise

Introduction

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Overview

T Category

N Category

Tips for Report

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Case 3 (63/M)

Staging Exercise

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N Category

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Case 3 (63/M)

Answer: T2N3

Staging Exercise

Introduction

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N Category

Tips for Report

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Case 4 (67/M)

Staging Exercise

Introduction

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Overview

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N Category

Tips for Report

Summary

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Case 4 (67/M)

Staging Exercise

Introduction

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Overview

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N Category

Tips for Report

Summary

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Case 4 (67/M)

Staging Exercise

Introduction

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Overview

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N Category

Tips for Report

Summary

References

Case 4 (67/M)

Answer: T4N1

Summary

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

T Category

• AJCC 9th Edition emphasizes clear bone involvement as the threshold for T3.
• Unequivocal cranial nerve involvement (particularly CN V and VI) or intracranial extension qualifies as T4.

→ Look for perineural spread via foramen rotundum, ovale, or into Meckel’s cave.

• IOF involvement is explicitly classified as T4, resolving prior ambiguity.

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N Category

• Advanced ENE (muscle, vessel, skin invasion) is now included as a criterion for N3.
• Fat stranding or irregular margins alone ≠ advanced ENE.
• Retropharyngeal ENE is excluded from N3 criteria.

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Summary

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

Reporting Tips

• Use a structured, anatomy-based approach aligned with AJCC 9th Edition.
• Always specify:
• Involved structures
• Nodal location, laterality, size, and ENE features
• Avoid vague terms; be definitive when features meet criteria (e.g., “muscle invasion,” “perineural spread”).

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“Accurate staging begins at the radiologist’s desk.”

References

Introduction

Objectives

Overview

T Category

N Category

Tips for Report

Summary

References

1. Amin MB, Edge SB, Greene FL, et al, eds. AJCC Cancer Staging Manual. 8th ed. New York: Springer; 2017.
2. Pan JJ, Mai HQ, Ng WT, et al. Ninth version of the AJCC and UICC nasopharyngeal cancer TNM staging classification. JAMA Oncol. 2024;10:1627.
3. Lee A, Huang SH, Chua M, American Joint Committee on Cancer. AJCC Cancer Staging System: Nasopharynx. American Joint Committee on Cancer; 2025.
4. Rai S, Xu CC, Olsen S, et al. The 9th version of the AJCC staging system for nasopharyngeal carcinoma: a guide for radiologists. AJR Am J Roentgenol. Published online 2025. doi:10.2214/AJR.25.33016
5. Razek AAKA, King A. MRI and CT of nasopharyngeal carcinoma. Am J Roentgenol. 2012;198:11–18.
6. Yu E, O’Sullivan B, Kim J, Siu L, Bartley E. Magnetic resonance imaging of nasopharyngeal carcinoma. Expert Rev Anticancer Ther. 2010;10:365–375.
7. Petersson F. Nasopharyngeal carcinoma: a review. Semin Diagn Pathol. 2015;32:54–73.
8. Pan JJ, Ng WT, Zong JF, et al. Proposal for the 8th edition of the AJCC/UICC staging system for nasopharyngeal cancer in the era of intensity-modulated radiotherapy. Cancer. 2016;122:546–558.
9. Xiao Y, Pan J, Chen Y, et al. The prognosis of nasopharyngeal carcinoma involving masticatory muscles: a retrospective analysis for revising T subclassifications. Medicine (Baltimore). 2015;94:e420.
10. Feng AC, Wu MC, Tsai SY, et al. Prevertebral muscle involvement in nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys. 2006;65:1026–1035.
11. Goh J, Lim K. Imaging of nasopharyngeal carcinoma. Ann Acad Med Singapore. 2009;38:809–816.
12. Glastonbury CM, Salzman KL. Pitfalls in the staging of cancer of nasopharyngeal carcinoma. Neuroimaging Clin N Am. 2013;23:9–25.
13. Medvedev O, Hedesiu M, Ciurea A, et al. Perineural spread in head-and-neck malignancies: imaging findings – an updated literature review. Bosn J Basic Med Sci. 2022;22:22–38.