Partial Breast Irradiation using adaptive MRgRT Shyama Tetar, radiation-oncologist VUmc Amsterdam 15-12-2017 5 th Vumc SBRT symposium 2017
Current practice Breast conserving treatment (BCT) Breast conserving surgery (BCS)/ lumpectomy Postoperative Whole Breast Irradiation o Hypofractionation: 16x 2.67Gy o Indication boost: 21x 2.20Gy breast + 21x 2.67Gy SIB
Current practice: treatment planning SIB
Rationale: Partial Breast Irradiation Majority of local recurrences occur in proximity to the tumor bed Less than 20% appear elsewhere in the breast Absolute number of failures is very low (<1%/year) Failures elsewhere are likely to be new primary breast cancer o Arose after initial therapy o Would not have been prevented by WBI Smith 2009, IJROBP
Benefits of Partial Breast Irradiation Smaller treatment volume Higher dose per fraction Shorter radiotherapy scheme Less number of fractions, for example 5x From 3-4 wk to a few days/ 1 week/ 1.5 weeks Less radiation exposure to OAR Breasts, Skin, Lungs, Heart Less toxicity Better cosmesis Recurrence/New Primary tumor, consider BCT again
Different Techniques for PBI Intra-operative radiotherapy Intra-cavitaryballoon brachytherapy Interstitial multi-catheter brachytherapy External beam RT
EBRT: Partial Breast Irradiation Florence-trial: RCT: WBI vs PBI, n= 520 pt WBI: 25 x 2 Gy + boost 5 x 2 Gy PBI: 5 x 6 Gy in 2wk, 4-5 coplanar 6MV beams, IMRT-technique IBTR @ 5jr: both groups 1,5% Significantly better toxicity (acute & late) and cosmesis above WBI External beam radiotherapy (EBRT): Dosimetric evaluation No invasive treatment Outpatient treatment / short duration Ipsilateral breast tumor recurrence minimal Livi, 215, EJC
Ongoing trial: NSABP B-39/RTOG 0413 A Randomized Phase III Study of Conventional Whole Breast Irradiation (WBI) vs Partial Breast Irradiation (PBI) for Women with Stage 0, I, or II Breast Cancer WBI 50-50,4Gy optional boost 60-66,6Gy PBI twice daily EBRT: 10 x 3,85 Gy Brachy: 10 x 3,4Gy Preliminary data (2008): 3311pt, median follow-up @ 19 months o No higher risk severe toxicity with EBRT Smith 2009, IJROPB Norris 2008
MRI-guided radiotherapy
Benefits of MRIdian versus CBCT Soft-tissue setup superior Setup on clips vs setup with MRI Real-time imaging and online gating Only 3mm PTV margin around CTV Adaptive plan optimization on surgical cavity Change of: seroma / position breast PARLOB Partial Breast Radiotherapy in Low-risk Breast cancer group using a MR-guided adaptive approach; a phase II study
Population: low risk good candidates/suitable GEC-ESTRO recommendation ASTRO consensus statement Polgar 2010, RO Smith 2009, IJROBP
Population: low risk GEC-ESTRO recommendation
PARLOB study: Prospective phase II Endpoints: PE: Toxicity in 1.5 year SE: Cosmesis, QoL Inclusion: low risk breast cancer N= 50 pt Treatment: 5 fracties of 6Gy or 6.5Gy Hypothesis: low tox / better cosmesis Combination of MRI-guided adaptive radiotherapy with smaller PTV-margin ensure no increasing toxicity with higher dose per fraction
PARLOB: Cosmetic outcome BCCT.core software Patient self-evluation questionnaire Breast shape Breast volume Deformity Nipple position Scar visibility Skin changes Panel evaluation Breast surgeon Plastic surgeon Layperson Haloua 2014, IJBC Cardoso 2007, The Breast
Treatment workflow PARLOB Consult + simulation (ipsilateral arm up) breath-hold in 17 sec 0,35T MR sim + CT sim Target volume and OAR delineation + Baseline treatment plan CTV= surgical cavity + isotropic margin of 1.5 cm PTV= CTV + 3mm Planning constraints conform RTOG 0413/NSABP B-39 Treatment 0,35 T MRI-scan + recontour deformed OAR Reoptimize baseline plan on current anatomy of the day MRgRT delivery with multiple breath-holds
PT1 PT2 PT3 PT4
Video feedback system for breath-hold Total treatment duration from setup: about 61 minutes Photography by Digidaan
PBI on the MRIdian
Take home messages PBI using adaptive MR guidance is feasible Accrual runs successfully Not everypatient needs activebreath-hold Challenges to expect Different location o Medial à constraints heart and contralateral breast / lung o Lateral à image quality