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Neck Dissection

Objectives. Natural history of metastatic neck diseaseTumour biologyOccult neck diseaseExtracapsular spreadClinical stagingCT/MRI/USS/PETOpen biopsy vs. sentinal nodeDifficult neck

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Neck Dissection

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    1. Neck Dissection Stephen Ball

    2. Objectives Natural history of metastatic neck disease Tumour biology Occult neck disease Extracapsular spread Clinical staging CT/MRI/USS/PET Open biopsy vs. sentinal node Difficult neck & contraindications Neck dissections

    3. Introduction Over 500 lymph nodes in the body 200 of these in the head & neck Normally 3mm – 3cm, most <1cm Many H&N tumours will undergo nodal spread Presence, absence, level & size of metastatic neck disease of significant prognostic determinant Literature confusing Retrospective analyses Non-randomised Selection bias Survival/locoregional control endpoint

    4. Natural history of Neck disease Key factors Tumour site Tumour size Tumour thickness <5mm 16% LN +ve, >5mm 64% LN +ve Previous treatment Tumour recurrence Tumour histology Tumour immunology

    5. Primary tumour site predictable based on distribution of cervical metastasis* Memorial Sloan-Kettering levels*

    7. Organ specific drainage

    9. Tumour biology Are lymph nodes favourable site for tumour growth Limitless replication vs. tumourlysis Cancer cells ? Lymphatic system via endothelial gaps Passive transport in lymph 2-4g tumour 4x106 cells/g/day* Anti-tumour/filtering function poorly understood

    10. SCC growth patterns within cervical LN* Subcapsular deposits growth within node ++ ? extranodal spread via capsular disruption Early extranodal spread from intranodal growth Malignant embolus ? subcapsular sinus + capsular lymphatics ? intra + extra nodal disease Only capsular embolus no intranodal disease ? early extranodal spread

    11. Stages of lymphatic metastasis Premetastatic invasion of tumour epithelial basal lamina Penetration of lamina Translocation of tumour cells through a lymphatic Exit from node Venous drainage Lymphatic drainage Direct spread

    12. Molecular detection of metastases Histologically normal tissue ? absence of tumour Molecular assays > 500x sensitive* Micro-array QRT-PCR Oligonucleotide mismatch assay Mitochondrial DNA mutations

    13. Occult nodal disease N0 N+ Neck ~25% Pathologically +ve nodes in 30% elective neck dissection* Occult neck disease can = subsequent clinical disease Subclinical spread ? early cancer Can only detect occult disease on removal Patients with micrometastasis 3x more curable than those with macroscopic disease* Literature currently does not justify discovering occult nodal disease on a routine basis N0 neck + risk occult mets from 10 site >20% consider SND 50% risk antr tongue, oropharynx & hypopharynx

    14. Extracapsular spread General consensus extracapsular spread = poor prognosis* Soft tissue invasion ?success by >80% Occult nodal disease & extracapsular spread poor prognosis No properly controlled prospective study comparing survival to extracapsular spread High risk patients (+ve resection margin, extranodal spread, perineural involvement) improved overall survival & locoregional control when treated with post op combined chemoradiation* ? tumour burden vs. ? tumour aggressiveness ? Depressed host-immune response?

    15. Clinical Staging UICC/AJC classification for regional cervical lymphadenopathy* Applies to all H&N tumours except nasopharynx & thyroid Criticisms Most important prognostic factors thought to be no. of nodes + extracapsular spread – neither can be measured clinically Clinical stage emphasises laterality Bilateral nodes ? worse prognosis eg. N1 supraglottis No independent classification of massive bilat nodes, often fixed & universally fatal.

    16. CT More accurate than clinical examination 647 neck dissections Sensitivity 84% Specificity 83% Clinical examination Sensitivity 74% Specificity 81 Especially useful in difficult necks: restaging, retropharynx As cancer invades the node Enlarges Necrotic centre Peripheral inflammation = rim enhancement CT nodes >1cm ~80% accuracy low-level II & high level III >1.5cm Difficulties: low-volume neck disease + residual/recurrent disease following surgery & irradiation

    17. MRI Similar accuracy to CT Size criteria similar Maybe better in evaluating N0 neck Window settings ~helpful in identifying malignant nodes Superparamagnetic iron oxide (SPIO) used as lymphangiographic agents Taken up up by RES in normal & inflammed nodes ? signal drop off No signal change in metastaic nodes

    18. Ultrasound Detect presence of cervical nodes Ability to differentiate malignant vs. benign limited Sensitivity ~75-95% Specificity ~63-91% Can be combined with FNA

    19. Radionuclide & PET Radionuclides e.g. Gallium-67, Technetium-99 dimercaptosuccinic acid (DMSA) Low sensitivity/specificity Inability to detect low volume disease PET – assess metabolic activity of nodes using 18 fluorodeoxyglucose (FDG)/ Still poor sensitivity/specificity for low volume disease CT/PET useful for: occult 10 Residual/recurrent disease following surgery & radiotherapy*

    20. Sentinal node Non-H&N melanoma + breast carcinoma Not routinely used: Exact nature of H&N lymphatic drainage unclear Skip metastasis do occur Collatral channels often present Necessitates operating in oncologically significant area Facial nerve risk in parotid nodes Learning curve & operator dependent Role limited to T1N0 oral cavity & oropharynx RCT by EORTC pending

    21. Open biopsy Generally avoided Equivocal cases/lymphoma/anaplastic carcinoma/FNAC not available No evidence in literature open Bx alters prognosis Provided correct treatment instigated within six weeks*. Incision should be planned to facilitate scar removal by subsequent standard neck dissection incision

    22. Difficult Neck Difficult to access Short stocky neck Recurrent disease Retropharyngeal nodes Extensive disease around vital structures Brachial plexus, prevertebral muscles, carotid Pre-op planning e.g. risk of hemiplegia by assessing collateral supply from circle of Willis.

    23. Contraindications Absolute vs. relative Primary tumour untreatable Medically unfit for anaesthetic Inoperable neck disease Fixation to skull base/brachial plexus Distant metastasis Radical radiotherapy/+- adjuvant chemotherapy/symptom palliation

    24. Recurrence & salvage surgery Poor prognosis 50% chance salvaging recurrent cancer in untreated neck 25% in electively irradiated neck 5% previously dissected neck*

    25. Neck Dissection 1906 Crile described classic radical neck dissection Popularised by Hayes Martin Comprehensive removal of all five lateral lymph node levels Selective

    26. Incision

    27. Radical neck dissection Removal of LN containing levels I-V All 3 non-lymphatic structures SAN SCM IJV

    28. Extended radical Radical neck dissection plus : One or more LN groups Retropharyngeal LN Parpharyngeal LN Parotid LN Level VI/VII LN Non-lymphatic structures Mandible Parotid Mastoid tip Prevertebral fascia & musculature Digastric Hypoglossal n. External carotid Skin Or both

    29. Modified radical neck dissection Removal of all level I-V LN with preservation =1 non-lymphatic structure Type 1 – SAN Type 2 – SAN & IJV Type 3 – SAN & IJV & SCM (functional)

    30. Selective neck dissection

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