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Parotid carcinoma ppt

Parotid cancers,anatomy, pathology, management and radiotherapy target volume contouring

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Parotid carcinoma ppt

  1. 1. Malignant Parotid Gland Tumours : Radiotherapy Perspective Dr. Gaurav Kumar Senior Resident Dept. of Radiotherapy SGPGI, Lucknow
  2. 2. Workup 1) History & Physical Examination ( Special emphasis on fixity of mass, neck nodes, facial nerve examination, trismus ) 2) Additional : Mirror and fibreoptic examination 3) CT/MRI of Face & Neck 4) Chest X-Ray (CT Thorax as clinically indicated) 5) FNA Biopsy 6) Routine Blood Parameters 7) Pure tone audiometry ( Additional)
  3. 3. Treatment Algorithm T1 & T2 (N0) Parotidectomy with complete resection of tumor (Neck dissection for high grade tumors) T1 & T2 (N+) Parotidectomy + Neck Dissection T3/T4/N+ Parotidectomy + Neck Dissection
  4. 4. Indications of Post operative Radiotherapy 1) T3/T4 tumors and/or 2) Incomplete or Close resection margin 3) High grade histology 4) Recurrent disease 5) Peri neural disease 6) Node + disease
  5. 5. Defining Parotid Bed: • The parotid gland extends from the zygomatic arch superiorly to beyond the lower border of the mandible inferiorly . • Posteriorly, the gland dips in the space between the mandible and the mastoid, with the adjoining external auditory meatus intimately surrounded by the gland in its free borders, that is, anteriorly and inferiorly. • On a deeper plane, the parotid is related to the styloid process and the muscles connected to it. Locoregional involvement : Local infiltration of tissues adjacent to the parotid gland is the main pattern of spread. This follows the anatomical borders of the parotid gland and in cases of perineural invasion, the facial nerve to the stylomastoid foramina.
  6. 6. • Soft tissue extension – The parotid gland, along with periparotid lymph nodes, facial nerve and vessels lie within the parotid facial compartment – The fascia is deficient in the medial aspect, thus an increased risk of spread to the parapharyngeal space.
  7. 7. • At risk areas: – Infratemporal fossa – Parapharyngeal space – Masseter – Diagastric – Skin • Bone infiltration - at risk areas include: – Lateral part of the floor of middle cranial fossa – Neck of mandible – External auditory meatus – Inferior surface of styloid process.
  8. 8. CLINICAL TARGET VOLUME DEFINITION (ICRU 50 & 62)
  9. 9. CLINICAL TARGET VOLUME SELECTION Position: Supine with arms by the side (use shoulder retraction) Immobilisation: Thermoplastic head and neck cast with head rest Planning CT Scan: 3mm slide (vertex to carina)
  10. 10. Superiorly: CT Slice passing through most lateral and superior extent of zygomatic arch (i.e. above TM Joint) Posteriorly: Posterior most attachment of pinna. Laterally: Skin Anteriorly: Posterior half of masseter. Medially: Infratemporal fossa and soft tissue plane in front of base of skull.
  11. 11. Anteriorly: Follows anterior border of masseter. Medially: Parapharyngeal space and lateral pterygoid plate Posteriorly: Include lateral retropharyngeal, soft tissue anterior to skull base and to include external auditary canal. Laterally: Skin
  12. 12. Below the level of external auditory canal/level of mastoid air cells Anteriorly: Anterior border of masseter Medially: Include Parapharyngeal space and lateral retropharyngeal nodes Posteriorly: Posterior border of mastoid process (posterior extent of mastoid air cells) and soft tissueplane anterior to skull base Laterally: Skin
  13. 13. Level of angle of mandible : Anteriorly: Anterior to the submandibular gland and includes level Ib nodal volume Medially: Medial border of level Ib and Submandibular gland, to include parapharyngeal space Posteriorly: To include level IIa and IIb nodal volumes Laterally: Skin
  14. 14. Inferior level : Superior cornu of hyoid bone Anteriorly : To include submandibular gland Medially : Medial border of level Ib and Submandibular gland, to include parapharyngeal space Posteriorly: To include nodal outlining of level IIb (following back to the sternocleidomastoid muscle) Laterally: Skin
  15. 15. When to apply skin bolus : Skin involvement • Poor prognostic indicator to develop distant metastasis • Relatively low incidence for local recurrence In order to obtain adequate skin dose, TMG recommends bolus in following situation: 1) Skin involvement 2) Close superficial margin 3) Tumor spillage/Capsular rupture
  16. 16. General points : • The margins described adapted to include any bone infiltration • The mandibular ramus is included in clinical target volume • Any air cavity is excluded from the clinical target volume Planning target volume: • Varies according to institution • Depends upon geometric accuracy of immobilisation system • PTV1 : Planning target volume to be treated to radical (in case of inoperable disease)or postperative dose • PTV2 : Planning target volume to be treated to an elective dose
  17. 17. Elective neck irradiation : (Neck not addressed by surgery) To include level Ib-IV TMG Consensus for elective nodal irradiation 1) High grade histolgy 2) T3/T4 disease 3) Histology: Squamous cell carcinoma Adenocarcinoma Undifferentiated carcinoma High grade mucoepidermoid carcinoma Salivary duct carcinoma
  18. 18. Post-operative neck irradiation : 1) Multiple nodes 2) > 2 nodal levels involved 3) Extracapsular spread + 4) N3 node Outlining Organs at Risk : • Both cochlea (with 3mm PRV) • Contralateral Parotid • Spinal Cord (with 3mm PRV) • Brainstem • Lens
  19. 19. Trial Management Group Recommendations : 1) Ipsilateral node group Ib-V are contoured and defined at risk nodal volumes 2) Ib, IIa, IIb commonly lie within surgical bed hence receive 60 Gy/30# dose 3) Patient without neck dissection, level III,IV,V are included in CTV2 (50 Gy/25# conventional or 54 Gy/30# in IMRT)in following situations • T3/T4 • All High Grade tumours • Histological subtypes Squamous cell carcinoma Adenocarcinoma Undifferentiated carcinoma High grade mucoepidermoid Salivary duct carcinoma
  20. 20. Trial Management Group Recommendations Continued: 4) Post-operative nodal irradiation recommended in: • Extracapsular spread • N2b disease • N3 status
  21. 21. Take Home Messages : 1) All T3/T4 should undergo Ipsilateral neck dissection (SOHND or preferably MRND) 2) T1/T2 N0 with favourable histology and low grade tumours can be spared of neck dissection and Primary & Neck node irradiation. 3) Ipsilateral level Ib,IIa,IIb nodes are always included in CTV1 (60Gy/30#) 4) If neck not addressed with surgery then it should be addressed during RT (even in case of cN0 status) in case of high grade tumours, T3/T4 disease and unfavourable histologies. 5) Recurrent tumours even if T1/T2 must receive PORT. 6) No role of concurrent chemotherapy till date (even in ECE). 7) Facial Nerve preservation in surgery and Cochlear sparing in Radiotherapy remains the state of art.
  22. 22. Thank You

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