Partial Breast Irradiation using adaptive MRgRT

Transcription

1 Partial Breast Irradiation using adaptive MRgRT Shyama Tetar, radiation-oncologist VUmc Amsterdam th Vumc SBRT symposium 2017

2 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

3 Current practice: treatment planning SIB

4 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

5 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

6 Different Techniques for PBI Intra-operative radiotherapy Intra-cavitaryballoon brachytherapy Interstitial multi-catheter brachytherapy External beam RT

7 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 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

8 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 19 months o No higher risk severe toxicity with EBRT Smith 2009, IJROPB Norris 2008

9 MRI-guided radiotherapy

10 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

11 Population: low risk good candidates/suitable GEC-ESTRO recommendation ASTRO consensus statement Polgar 2010, RO Smith 2009, IJROBP

12 Population: low risk GEC-ESTRO recommendation

13 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

14 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

15 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

16 PT1 PT2 PT3 PT4

17 Video feedback system for breath-hold Total treatment duration from setup: about 61 minutes Photography by Digidaan

18 PBI on the MRIdian

19 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

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