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IGRT & IMRT In Head Neck Cancer

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IGRT & IMRT In Head Neck Cancer

  1. 1. IMRT & IGRT for Head Neck Cancers Dr Sapna Nangia Chief Radiation Oncologist International Oncology Centre Fortis Hospital Noida
  2. 2. PARSPORT trial : Category I Evidence in support ofefficacy of IMRT in reducing xerostomia Nutting et al Lancet Oncol 2011 12 (2) 127
  3. 3. PARSPORT trial : Numbers not enough to establish non-inferiority. Conventional IMRT radiotherapy 2 yr LR PFS 80% 78%Estimated 2 yr 76% 78% OS
  4. 4. Contouring the CTV – Learning New Skills Anatomical Boundary Cranial Caudal edge of lateral process of C1 Caudal Caudal edge of the body of hyoid bone Anterior Post. edge of sub-mandibular gland, ant. edge of int. carotid artery, post. edge of post. belly of digastric m. Posterior Post. border of the sternocleidomastoid m Medial Medial edge of int. carotid artery, paraspinal (levator scapulae) m. Lateral Medial edge of Cranial Boundary sternocleidomastoid
  5. 5. Contouring the CTV – Patterns of spread & failure Buccal Mucosa lesions involve the buccinator muscle and buccal fat pad Alveolar and retromolar trigone lesions involve bone early; Mandibular canal and inferior alveolar nerve / maxillary antrum and floor of nose – potential routes & sites of spread, respectively. Bone Involvement : Absence of fixation to bone / small size of a mandibular lesion, does not rule our bone involvement. INTRATEMPORAL FOSSA
  6. 6. Contouring the CTV – Patterns of spread & failure Buccal Mucosa lesions involve the buccinator muscle and buccal fat pad Alveolar and retromolar trigone lesions involve bone early; Mandibular canal and inferior alveolar nerve / maxillary antrum and floor of nose – potential routes & sites of spread, respectively. Bone Involvement : Absence of fixation to bone / small size of a mandibular lesion, does not rule our bone involvement. Yao et al IJROBP 2007 INTRATEMPORAL FOSSA 55 pts, oral cancer alone. Mostly postoperative IMRT 2/9 locoregional failures in the infratemporal fossa
  7. 7. Contouring the CTV – Lymph Node Involvement in N0 neck Level I Level II Level III Level IV Level VBuccal 44 11 0 0 0MucosaAlveolus 27 21 6 4 2Retro Molar 19 12 6 6 0Trigone Gregoire, R O 2000, 56, 135
  8. 8. Contouring the CTV – Lymph Node Involvement in N+ neck Level I Level II Level III Level IV Level VBuccal 82 42 65 65 0MucosaAlveolus 54 46 19 17 4Retro Molar 50 60 40 20 0Trigone Gregoire, R O 2000, 56, 135
  9. 9. The Node Positive Neck  What is a positive neck node ( Consensus at the 43rd meeting of ASTRO, San Fransisco,2001)  >1 cm in size ( 1.5 cm if jugulodigastric)  Shape spherical rather than ellipsoidal  Necrotic center, irrespective of size  Cluster of 3 or more borderline nodes  Our departmental protocol: Delineate ALL clinically & radiologicaly apparent nodes, irrespective of above criteria. Eisbruch et al, Seminars in Rad Onco 12 238- 249
  10. 10. Impact Of Patterns Of Failure On TargetDelineation StrategyResults Impact on PracticeDawson et al & Eisbruch et al2/58 failure & 21/133failures ,all in field Safe to omit contralat high level II if c/l neck negative3 RP node failures, all superior to CI vert Superior extent of RP nodes is base of skullIpsilat high Level II failure in OC & OP Consider treating ipsilateral high Level II in casePrimaries of OP primaries, even if N0Bussels et al2/72 failures at matchline . Consider including supraclavicular fossa in a single IMRT plan. Gregoire et al R & O 56 (2000) 135±150
  11. 11. Impact Of Patterns Of Failure On TargetDelineation StrategyResults Impact on PracticeCannon et al ? Do not disregard any nodules in a nodeNoted 3 periparotid failures, two in positive neck, even if radiologicaly / PETpatients with bilateral disease. insignificantRetrospectively, insignificant nodulesnoted in periparotid regionOne dermal failure in periparotid region in ?Consider sparing only the contralateral neckipsilateral neckNangia et al Investigation into dose ecscalation , hypoxia30/83 locoregional failures , 28 of which sensitisationwere within the high dose volumeNo failure in the area outlined as low riskvolume, using RTOG guidelines for Nodal delineation criteria validateddelineation of levels and using the 5 % cutoff for deciding which nodal levels toinclude Cannon et alIJROBP 70, (2008)660–665, Nangia et al, IJROBP In press
  12. 12. Results Eighty three patients  WDSCC 36  Larynx 35  MDCC 27  Hypopharynx 13  PDCC 16  Base tongue 17  Oral tongue 06  N0:N1:N2:N3 = 36:10:32:5  Oral cavity 02  TX:T2:T3:T4 = 3:29:37:14  MUO 03 LRFS at 3 years 60.8% OS at 3 years 81.7%
  13. 13. Treatment Related Factors AffectingOutcomeTotal Treatment Time < 53 Days/ > 53 days; Volume of 70Gy PTV <177cc/>177cc
  14. 14. Treatment Related Factors Affecting OutcomeCoverage of 70Gy PTV by Prescription dose >91% /<91%; Minimum Dose to 70Gy PTV >54Gy /<54 Gy
  15. 15. Model For Predicting Locoregional Relapse  Hazard of Locoregional Relapse [100 –( 1.07x X 100)] + [100 –( 0.91y X 100)] x = change in total treatment time y = change in coverage for V 100% for 70Gy PTV
  16. 16. Prescription for Head Neck IMRT60Gyequivalent GTV + Margin* 70Gy / 35 # N o d e70Gy/ 35# 50Gy Equivalent
  17. 17. Prescription for Head Neck IMRT 95% prescription dose to cover 98% of high dose PTV Prescription dose to cover at least 91% of high dose PTV 95% dose to cover at least 95% of low risk PTV Avoid hotspots >107% Parotid PRV Spine Mandible
  18. 18. Image Guided Radiotherapy“Image-guided radiation therapy(IGRT) is the process of frequenttwo and three-dimensionalimaging, during a course ofradiation treatment, used todirect radiation therapy utilizingthe imaging coordinates of theactual radiation treatment plan.”  EPID  kV-kV  CBCT  CT on rails  Fluoroscopy
  19. 19. The questions being asked today -IMRT IGRT OAR besides the parotid  Are we ensuring accurate Improving results treatment  Imaging for target  Can PTV margins be delineation trimmed below 5 mm  Hypoxia targeting  What are the serial  Dose escalation changes that take place Is SIB better than sequential during RT boost  Are we ready for adaptive planning
  20. 20. OARs besides the Parotid : Brachial Plexus  Three distinct syndromes  Transient neuropathy  Classic, delayed, progressive fibrosis - unlikely to occur <60 Gy  Acute ischemic plexopathy  Dose constraints  RTOG 0412 (RT+CT): 60 Gy/30 #  RTOG 0615 (RT+CT): 66Gy/303#
  21. 21. OARs besides the Parotid : TM Joint Trismus related to Pre RT Post RT  Post radiotherapy fibrosis MID MID  Scarring of muscles and ligaments around TM joint Conventional RT 44.68 cm 32.7 cm  Fibrosis and scarring of ( Wang et al (73.1%) the pterygoid muscles Laryngoscope, 2005, 115. ) Can be measured by Maximal Interincisor IMRT 46.2cm 45.4 distance ( MID) ( Hsiung et al BJR , ( 98.1)% 2008, 809) Especially important for nasopharyngeal cancer
  22. 22. OARs besides the Parotid : Thyroid Proposed constraints : 20% volume <20 Gy; 10% volume <30 Gy; 5%volume <40 Gy Maximum dose 50 Gy. Diaz, IJROBP 2010, 77,2, 468
  23. 23. OARs besides Parotid : DARS  Post-therapy abnormalities  Aspiration contributing to a high rate of  PC Mean dose >60 Gy aspiration:  PC V65 Gy > 50%  weakness of the posterior motion of base tongue  SGL V50 Gy >50%  prolonged pharyngeal transit  Stricture time  PC V70 Gy >50%  lack of coordination between the swallowing phases  reduced elevation of the larynx  reduced laryngeal closure and epiglottic inversionEisbruch IJROBP 2007 69 s 42
  24. 24. Other OARs besides Parotid : Miscellaneous ConstraintsCochlea < 45 - 50 Gy Sensorineural deafness starts at 45Gy. Significantly increased at 60 Gy. Starts at 10 Gy if cisplatin used, especially for higher frequenciesOptic Retina < 45 Gy Optic chiasm dose > 60 Gy, optic neuropathy 11% -apparatus Optic nerves & 47 %depending on fraction size, cut off 1.9 Gy chiasm <54 GyTemporallobes
  25. 25. Other OARs besides Parotid : Miscellaneous ConstraintsLacrimal Same as Severe dry eye syndrome, 100% at 57%. Can resultGland parotid in visual loss secondary to ulceration, opacification and neovascularisation.Carotid Narrowing in 50 % vessels after 40Gy.Post RT 79% patients likely to have significant stenosis.Mandible Max dose Dental Extractions; occur more often if max mandible < 70 mandibular dose > 70Gy, mean mandibular dose Gy/ 75Gy. >40 Gy. Incidence of ORN < 1% Mean dose < 40Gy
  26. 26. Can PTV margins be trimmed to < 5 mm Margin : 5 mm in 95 pts Margin : 3 mm in 130 pts No difference in marginal failures Margins can only be reduced with daily image guidance Shift > 3mm ML 10% SI 26% AP 18% Chen et al Head Neck 2011 JulyChen, IJROBP Article in press
  27. 27. IGRT : Calculating PTV margins pertinent toa setup ( patient & departmental) van Herk’s recipe for Wk2Lat Wk2Longi Wk2Vert PTV : -1.00 0.00 -2.00 -3.00 3.00 -1.00 3.00 0.00 4.00 1.00 0.00 -3.00 -4.00 1.00 -6.00 0.00 0.00 0.00 -3.00 -1.00 1.00 3.00 0.00 0.00 2.5 Σ + 0.7 σ 0.00 2.00 0.00 -1.00 -2.00 0.00 0.00 1.00 1.00 -4.00 2.00 7.00 2.00 1.00 -2.00 -2.00 -1.00 2.00 -2.00 -3.00 2.00Σ: SD of mean of all means 2.00 0.00 1.00 1.00 1.00 0.00σ: -2.00 -2.00 0.00 sum of all SDs ( actually -1.00 -2.00 1.00RMS) 0.00 0.00 -3.00 -1.00 -3.00 3.00 4.00 3.00 0.00 -4.00 -1.00 2.00 -1.00 0.00 -1.00 -2.00 -4.00 -1.00
  28. 28. SIB or Sequential Boost ?SIB: Ease of planning Radio-biologically sound Clinical results vouch for efficacySEQ: Standard fractionation Cone down fields allow bettersparing of normal tissuesE. Lamers-Kuijper R O 2011 98 51
  29. 29. Are we ready for adaptive planning
  30. 30. Weekly Volumetric Changes • Greatest reduction in CTV 1, 3.2 % between week 0 & 2 ( significant) • Statistically significant reduction in volume of CTV 2 , 10.5% and 5.5% between wk 0 & 2 and 2 &4 respectively • Parotid shrinks 14 % and 16% , wk 0&2, wk 2& 4 respectively • Significant reduction in minimum dose to CTV and increase in mean dose to parotid
  31. 31. Weekly Volumetric Changes • Greatest reduction in CTV 1, 3.2 % between week 0 & 2 ( significant) • Statistically significant reduction in volume of CTV 2 , 10.5% and 5.5% between wk 0 & 2 and 2 &4 respectively • Parotid shrinks 14 % and 16% , wk 0&2, wk 2& 4 respevtively • Significant reduction in minimum dose to CTV and increase in mean dose to parotid
  32. 32. Weekly Volumetric Changes • Greatest reduction in CTV 1, 3.2 % between week 0 & 2 ( significant) • Statistically significant reduction in volume of CTV 2 , 10.5% and 5 5 between wk 0 & 2 and 2 &4 respectively • Parotid shrinks 14 % and 16% , wk 0&2, wk 2& 4 respectively • Significant reduction in minimum dose to CTV and increase in mean dose to parotid •
  33. 33. Adaptive Planning - Before
  34. 34. Adaptive Planning - AfterImproved coverage / better sparing of OAR in 65% of cases of 23 patients who underwentrepeat scans at 11th, 22nd and 33rd fraction. Ahn et al IJROBP2011 80 3 677
  35. 35. Indications for implementing adaptiveplanning – Ahn etal
  36. 36. Indications for implementing adaptiveplanning – Ahn etalD max cord > 45 GyPTV-tumor or PTV-node D95% below 95% of prescriptionParotid D50% increased significantly above 26 GyMandible V60 Gy above 10%,Brainstem V54 Gy above 20%
  37. 37. Work In Progress Hypoxia targeting Dose escalationChange in hypoxic area ( and therefore boost target volume) 3 days apart in 4/7 patients Lin et al IJROBP 2008 70,4, 1219

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