Proton radiotherapy for chest wall and regional lymphatic radiation; dose comparisons and treatment delivery

Abstract

PurposeThe delivery of post-mastectomy radiation therapy (PMRT) can be challenging for patients with left sided breast cancer that have undergone mastectomy. This study investigates the use of protons for PMRT in selected patients with unfavorable cardiac anatomy. We also report the first clinical application of protons for these patients.Methods and materialsEleven patients were planned with protons, partially wide tangent photon fields (PWTF), and photon/electron (P/E) fields. Plans were generated with the goal of achieving 95% coverage of target volumes while maximally sparing cardiac and pulmonary structures. In addition, we report on two patients with unfavorable cardiac anatomy and IMN involvement that were treated with a mix of proton and standard radiation.ResultsPWTF, P/E, and proton plans were generated and compared. Reasonable target volume coverage was achieved with PWTF and P/E fields, but proton therapy achieved superior coverage with a more homogeneous plan. Substantial cardiac and pulmonary sparing was achieved with proton therapy as compared to PWTF and P/E. In the two clinical cases, the delivery of proton radiation with a 7.2 to 9 Gy photon and electron component was feasible and well tolerated. Akimbo positioning was necessary for gantry clearance for one patient; the other was treated on a breast board with standard positioning (arms above her head). LAO field arrangement was used for both patients. Erythema and fatigue were the only noted side effects.ConclusionsProton RT enables delivery of radiation to the chest wall and regional lymphatics, including the IMN, without compromise of coverage and with improved sparing of surrounding normal structures. This treatment is feasible, however, optimal patient set up may vary and field size is limited without multiple fields/matching.

Postmastectomy Scar Boost Irradiation Using HDR Surface Mould Brachytherapy by 3D Image-Based Volume Optimization

“…Moreover, efforts are also made to develop atlas-based guidelines for implementing uniformity in delineation of the target and critical structures which are expected to minimize the interpersonal variations [13]. In PMRT, by implementing these technologies and using electronsphoton combinations, it is expected to bring down the pulmonary or cardiac toxicities [14][15][16][17][18].…”

État des lieux et perspectives de la protonthérapie

“…L'avantage de la protonthérapie dans ces cas-là est de réduire l'irradiation cardiaque, en moyenne proche de 0-1 Gy, faisant anticiper une disparition quasi complète des complications cardiaques à long terme. L'autre avantage de la protonthérapie est de faire drastiquement chuter les volumes d'irradiation à faible dose [25], faisant également prédire une diminution des cancers radio-induits. Les premières séries d'irradiation mammaire par protons viennent d'être publiées et confirment la réduction des volumes d'irradiation [26][27][28].…”

Proton radiotherapy for treating the most common carcinomas

“…Doses ranging at 30-50 Gy RBE in 10-24 fractions are well tolerated; skin reactions of G1-2 severity are observed in 60-79% cases, telangiectasia at G1 grade in 15-26% and a cosmetic effect, self-assessed by the patients, as being good or satisfactory in 80-90% [65,[81][82][83][84].…”

“…Studies that compare dosimetry parameters for radiotherapy in BC patients, indicate that the irradiated heart volume, which receive high or low dose (V20, V5), is reduced when using a proton beam compared with photon beams; where mean heart doses are respectively 19 Gy vs 23-25 Gy [62][63][64][65][66][67][68]. The probability of cardiac complications was estimated at 0.5% for the proton beam and 2.1% for the photon beam radiotherapy [69].…”