ESTRO 2022

Session Item

Dosimetry

Session Code: 6034

Session Type: Poster (digital)

Track: Physics

An international, multicenter planning study on regional nodal irradiation in breast cancer

Marciana Nona Duma, Germany

Presentation Number: PO-1569

Abstract

Abstract Title:

An international, multicenter planning study on regional nodal irradiation in breast cancer

Authors:

Marciana Nona Duma¹, Birgitte Vrou Offersen², Marianne Bessermann Johansen³, Kristian Boye⁴, Bente Sommer Kristensen⁴, Icro Meattini⁵, Livia Marrazzo⁶, Vanessa Di Cataldo⁷, Alex De Caluwé⁸, Danilo Teixeira⁹, Pierfrancesco Franco¹⁰, Gianfranco Loi¹¹, Ingelise Jensen¹², Mette Møller¹³, Karolien Verhoeven¹⁴, Romain Marseguerra¹⁵, Kirsten Legård Jakobsen¹⁶, Sami Aziz-Jowad Al-Rawi¹⁶, Youlia Kirova¹⁷, Barbara Alicja Jereczek-Fossa¹⁸, Maria Cristina Leonardi¹⁹, Rosa Luraschi²⁰, Isabelle Kindts²¹, Laurence Goethals²¹, Pierre Loap¹⁷, Jeremi Vu-Bezim¹⁷, Steffen Weimann²², Tobias Teichmann²², Andrea Wittig²²

¹University Hospital Jena, Department of radiotherapy and radiation oncology, Jena, Germany; ²Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark; ³Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; ⁴Rigshospitalet, Department of Oncology, Copenhagen, Denmark; ⁵University of Florence; Careggi University Hospital, Experimental and Clinical Sciences “Mario Serio”; Radiation Oncology Unit, Florence, Italy; ⁶Medical Physics Unit, Careggi University Hospital, Florence, Italy; ⁷IFCA, Radiation Oncology Department, Florence, Italy; ⁸Institut Jules Bordet, Université Libre de Bruxelles; AZ St Maarten, Radiation Oncology department, Brussels, Mechelen, Belgium; ⁹Institut Jules Bordet, Université Libre de Bruxelles, Medical Physics department, Brussels, Belgium; ¹⁰University of Eastern Piedmont; ‘Maggiore della Carità’ University Hospital, Department of Translational Medicine (DIMET), Department of Radiation Oncology, Novara, Italy; ¹¹ ‘Maggiore della Carità’ University Hospital, Department of Medical Physics, Novara, Italy; ¹²Aalborg University Hospital, Department of Medical Physics, Aalborg, Denmark; ¹³ Aalborg University Hospital, Department of Oncology, Aalborg, Denmark; ¹⁴GROW School for Oncology, Maastricht University Medical Center, Department of Radiation Oncology (MAASTRO), Maastricht, The Netherlands; ¹⁵ Zealand University Hospital, Rigshospitalet, Department of Clinical Oncology and Palliative Care, Department of Oncology, Næstved, Copenhagen, Denmark; ¹⁶Zealand University Hospital, Department of Clinical Oncology and Palliative Care, Næstved, Denmark; ¹⁷Institut Curie, Department of Radiation Oncology, Paris, France; ¹⁸IEO, European Institute of Oncology IRCCS; University of Milan, Division of Radiation Oncology, Department of Oncology and Hematoncology, Milan, Italy; ¹⁹IEO, European Institute of Oncology IRCCS, Division of Radiation Oncology, Milan, Italy; ²⁰IEO, European Institute of Oncology IRCCS, Unit of Medical Physics, Milan, Italy; ²¹Cancer Centre, General Hospital Groeninge, Department of Radiation Oncology, Kortrijk, Belgium; ²²University Hospital Jena, Department of radiotherapy and radiation oncology , Jena, Germany

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Purpose or Objective

The inter-institutional variability in planning objectives and constraints are expected to be very large in regional nodal irradiation (RNI) since no international guidelines are available specific for breast cancer (BCa) treatment planning,. The aim of this international study was to assess the decision making process as well as the planning of RNI in experienced European BCa centers.

Material and Methods

The planning part of the study focused on a left-sided “total” RNI scenario (Level I – IV+internal mammary chain-(IMC)), including the breast. Two datasets were chosen: a dataset of a regular (R_pt) patient (BMI:24.5; breast vol.:680cm³) and an adipose (A_pt) patient (BMI:31; breast vol.:1260cm³). The CTVs, PTVs and OARs were centrally contoured. The CTV was generated according to the ESTRO contouring guideline in free breathing(FB) and deep inspiration breath hold(DIBH); PTV=CTV_breast+1cm and CTV_RNI+0.6cm, respectively. The organs at risk (OAR) were: the heart, the left anterior descending artery (LAD), the lungs, the brachial plexus, the esophagus, the humeral head and the thyroid gland. All participants received the same DICOM datasets with the recommendation to perform the treatment planning for 40.05/2.67Gy with the in-house technique, PTV and OAR constraints. The final plan and dose files, were sent back as DICOM files. We analyzed for each CTV the D99%,D98%,D95%,D50%,D1% and V95%; for the OAR the D1%,Dmean,V20Gy,V30Gy, V40Gy and the absolute V95% of normal tissue outside the PTV. We report average±standard deviation and/or median (range).

Results

The techniques used were: tomotherapy, 3D-conformal, volumetric modulated radiotherapy, hybrid techniques (Fig.1).

Differences in the coverage A_pt vs.R_pt of the CTV_breast (higher D2%/D1% for A_pt; p=0.031) and CTV_IMC (lower D50% for A_pt; p=0.014) were significant. There was a statistically (p=0.037) significant larger V95% outside the PTV in the A_pt vs. the R_pt (324.48cm³±211 vs. 251.78cm³±144). Overall, there were statistically significant better D99%, D98%, D95%, D50% CTV_IMC values in the DIBH plans compared to the FB plans. Nonetheless this led to significantly (p=0.021/p=0.008) higher (by 5cm³±7.11cm³/11cm³±12.6cm³) V40Gy/V30Gy to the contralateral breast in DIBH compared to FB. The CTV_IMC V95% for the A_pt was in DIBH/FB: 88.1%(62.6%-100%)/62.8%(6.9%-99.9%) and for R_pt: 78.6%(62.3%-100%)/91%(45.7%-99.9%),respectively. Due to the treatment planning approach with an optimization of heart doses in the FB plans (at a cost of a lower CTV_IMC coverage), there was no statistically significant difference in the Dmean heart between the DIBH and FB plans. There was a small significant difference in the Dmean heart dose between the R_pt (4.04Gy±1.09Gy) vs. A_pt patient (5.19Gy±2.4Gy)(Fig2.).

Conclusion

RNI remains a challenge in breast cancer treatment. Our analysis quantifies for the first time the existing inter-institutional variability in the treatment planning approach and the treatment decision.