Bundhit Tantiwongkosi, MD Frank R. Miller, MD University of Texas Health Science Center San Antonio, TX Annual Scientific Meeting American Society of Neuroradiology Chicago, IL April 25-30, 2015 T4a versus T4b of Head Neck Cancers: Current Concepts beyond Resectibility Issues Control #: 387 eEdE#: eEdE-95

 7 th Edition of American Joint Committee of Cancer (AJCC) staging defines T4a and T4b HN cancers as moderately advanced local and very advanced local disease respectively, instead of resectable and unresectable disease per the 6 th edition  Differences between the two stages are greatly important because they dictate treatment options and patient prognosis Introduction

Table of Content Oral Cavity Oral Cavity Oropharynx Larynx Hypopharynx References

Oral Cavity Cancer: T4a Oral Cavity Cancer: T4a Mucosal Lips, Buccal Mucosa, Upper & Lower Alveolar Ridges, Retromolar Trigone, Floor of Mouth, Hard Palate, Anterior 2/3 Tongue Structure involvedSurgery Extrinsic Tongue Muscles (A) Glossectomy with 1 cm margins Cortical Bone (B)Marginal or lingual mandibulectomy Medullary Bone (C)Segmental mandibulectomy Skin (D)Wide local excision with 1-2 cm margins Maxillary Sinus (E)Infrastructure, partial or total maxillectomy A B C D E A: FOM cancer (↓) involves M. Genioglossus (→) B: Oral tongue cancer (↑) involves lingual mandibular cortex (→) C: RMT cancer (↓) involves mandibular medulla (→) D: Mandibular alveolar ridge cancer (→)involves skin (↑) E: RMT cancer (↑) involves maxillary sinus (→) Surgery is followed by Radiation +/- CMT

Oral Cavity Cancer: T4b Structure involvedSurgery Masticator spaceExtended Total Maxillectomy/Mandibulectomy Pterygoid platesUnresectable ICACarotid artery resection with possible bypass (often deemed unresectable due to high rate of stroke) Skull baseSkull base resection (usually not surgically possible) Main treatment for T4b oral cavity cancer is chemoradiation with poorer local control when bone involvement occurs. Surgery options are limited as above A & B: Primary RMT cancer (→) involves M. Buccinator (↓), M. Medial Pterygoid (↑), M Massector, Pterygoid plates (←) B A

Oropharyngeal Cancer: T4a Base of Tongue (BOT), Palatine Tonsils, Soft Palate, Posterior Pharyngeal Wall : from hard palate to vallecula floor Oropharyngeal Cancer: T4a Base of Tongue (BOT), Palatine Tonsils, Soft Palate, Posterior Pharyngeal Wall : from hard palate to vallecula floor Structure involved Surgery Extrinsic Tongue Muscles (A) Glossectomy with 1 cm margins Medial pterygoid muscle (B) Extended Maxillectomy Larynx (C) Total laryngectomy Hard palate (D,E)Infrastructure Maxillectomy Mandible (not shown)Segmental Mandibulectomy A A B C D E A: BOT cancer (→) involves M. Genioglossus (←) B: Oropharyngeal wall cancer (↑) involves M. Medial Pterygoid (←) C: BOT cancer (↑) involves suprglottic larynx (←) D&E: Palatine tonsil cancer (→) involves maxillary sinus (↑) Both T4a and T4b OP cancers are treated with radiation first +/- CMT for organ preservation with possible surgical salvage for local failure in selected patients.

Oropharyngeal Cancer: T4b Structure involved Surgery M. Lateral Pterygoid (A) Unresectable Pterygoid plate (B) Unresectable Skull base (C)Skull base resection (usually not surgically possible) Nasopharynx (D)Wide local excision with 1 cm margin (usually not feasible) ICA (E)Carotid artery resection with possible bypass (often deemed unresectable due to high rate of stroke) A&B: Palatine tonsil cancer (→) involves M. Lateral Pterygoid (←) and pterygoid plate (→) C&D: Palatine tonsil cancer (↑) involves skull base ( → ) and lateral nasopharyngeal wall (←) E: Palatine tonsil cancer extends to encase ICA 360 degrees (→) Both T4a and T4b OP cancers are treated with radiation first +/- CMT for organ preservation with possible surgical salvage for local failure in selected patients. A D B E C

Larynx: T4a Supraglottic, glottic, subglottic Structure involvedSurgery Through thyroid cartilageTotal laryngectomy with thyroid lobectomy if i nvolved Extralarngeal soft tissue (strap muscle, trachea, esophagus, thyroid, tongue) Total laryngectomy with removal of involved ti ssues to achieve 1 cm margins (i.e. thyroid lobectomy; partial glossectomy; cervical esophogectomy) Total laryngectomy is followed by radiation +/- concurrent CMT A B A: Glottic cancer (→) involves through right thyroid cartilage B: Glottic cancer (→) destroys the anterior aspect of the thyroid cartilage to involve the strap muscles and soft tissue

Larynx: T4b Supraglottic, glottic, subglottic Structure involvedSurgery Prevertebral spaceUnresectable Carotid arteryCarotid artery resection with possible bypass (often deemed unresectable due to high rate of stroke) MediastinumUnresectable Chemoradiation is the mainstay of treatment with limited surgical options A B A&B: A large transglottic cancer (→) involves the left side of the prevertebral space (↑)

Hypopharynx: T4a Postcricoid Region, Pyriform sinuses, Posterior Paryngeal Wall: From vallecular floor to inferior border of the cricoid ring Structure involvedSurgery Thyroid/cricoid cartilages: Laryngopharyngectomy Central compartment soft tissue (strap muscle, subcutaneous fat) Laryngopharyngectomy with resection of additional soft tissue to achieve 1 cm margins Thyroid glandLaryngopharyngectomy with thyroid lobectomy Chemoradiation is the treatment of choice in order to preserve organ function with the surgical options as above A B A&B: Right pyriform sinus cancer (↑) invades through the right thyroid cartilage (←), right strap muscle (↓)and subcutaneous fat (→)

Hypopharynx: T4b Structure involvedSurgery Prevertebral spaceUnresectable Carotid arteryCarotid artery resection with possible bypass (often deemed unresectable due to high rate of stroke) MediastinumUnresectable Chemoradiation is the mainstay of treatment with limited surgical options A&B: Right pyriform sinus cancer (↑) involves the aryepiglottic fold (←), crosses the midline and invades the right prevertebral space (↑)

Take Home Points  T4a disease is anatomically resectable but patients often undergo non-surgical treatment due to overall poor prognosis, poor performance status, or quality of life issues  T4b disease has limited surgical options and chemoradiation is the main treatment  Precise localization of tumor invasion is crucial in staging and treatment planning  AJCC establishes criteria of staging in each sub site that radiologists need to follow for uniform staging and follow up

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