Proton pencil beam scanning reduces secondary cancer risk in breast cancer patients with internal mammary chain involvement compared to photon radiotherapy

Radiation Oncology

Chiara La Tessa¹  Francesco Tommasino¹  Giorgio Cartechini¹  Loris Menegotti²  Francesco Fracchiolla³  Paolo Farace³  Emanuele Scifoni⁴  Marco Schwarz⁵ 

[1] Department of Physics, University of Trento, Via Sommarive, 14, 38123, Povo, TN, Italy;Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics, (INFN), Povo, Italy;Health Physics Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy;Protontherapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy;Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics, (INFN), Povo, Italy;Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics, (INFN), Povo, Italy;Protontherapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy;

关键词: Secondary cancer risk;    Breast cancer;    Proton therapy;    Tangential 3D-CRT;    VMAT;   

DOI  :  10.1186/s13014-020-01671-8

来源: Springer

【 摘 要 】

PurposeProton pencil beam scanning (PBS) represents an interesting option for the treatment of breast cancer (BC) patients with nodal involvement. Here we compare tangential 3D-CRT and VMAT to PBS proton therapy (PT) in terms of secondary cancer risk (SCR) for the lungs and for contralateral breast.MethodsFive BC patients including supraclavicular (SVC) nodes in the target (Group 1) and five including SVC plus internal-mammary-nodes (IMNs, Group 2) were considered. The Group 1 patients were planned by PT versus tangential 3D-CRT in free-breathing (FB). The Group 2 patients were planned by PT versus VMAT considering both FB and deep-inspiration breath hold (DIBH) irradiation. The prescription dose to the target volume was 50 Gy (2 Gy/fraction). A constant RBE = 1.1 was assumed for PT. The SCR was evaluated with the excess absolute risk (EAR) formalism, considering also the age dependence. A cumulative EAR was finally computed.ResultsAccording to the linear, linear-exponential and linear-plateau dose response model, the cumulative EAR for Group 1 patients after PT was equal to 45 ± 10, 17 ± 3 and 15 ± 3, respectively. The corresponding relative increase for tangential 3D-CRT was equal to a factor 2.1 ± 0.5, 2.1 ± 0.4 and 2.3 ± 0.4. Group 2 patients showed a cumulative EAR after PT in FB equal to 65 ± 3, 21 ± 1 and 20 ± 1, according to the different models; the relative risk obtained with VMAT increased by a factor 3.5 ± 0.2, 5.2 ± 0.3 and 5.1 ± 0.3. Similar values emerge from DIBH plans. Contrary to photon radiotherapy, PT appears to be not sensitive to the age dependence due to the very low delivered dose.ConclusionsPBS PT is associated to significant SCR reduction in BC patients compared to photon radiotherapy. The benefits are maximized for young patients with both SVC and IMNs involvement. When combined with the improved sparing of the heart, this might contribute to the establishment of effective patient-selection criteria for proton BC treatments.

【 授权许可】

CC BY