Abstract P6-09-08: Can proton therapy for localized mediastinal Hodgkin's lymphoma reduce second breast cancer incidence?

Abstract

Abstract Introduction Secondary breast cancer (SBC) is a recognized late complication of radiation therapy, after treatment for Hodgkin lymphoma (HL), with reported relative risks as high as 50 with older techniques (Mantle Field). Within the past, it has been estimated that reduction in dose and volume will reduce the incidence of late complications such as secondary neoplasms and cardiovascular disease. We evaluate the impact of mediastinal proton therapy on potential limitation of SBC risk. Material & methods For 14 young female patients with early-stage, mediastinal HL, treated with chemotherapy and involved-field raditation therapy (IFRT), we simulated similar treatment plans with conformal radiotherapy (CRT), helical tomotherapy (HT) and proton therapy at the dose of 30 Gy. We report the respective doses to the breasts. Treatment plans were not specifically designed for breast sparing. Results Proton therapy significantly lowered the dose to the breasts, with mean doses of 2,76/1,53 Gy to the left and right breast respectively with proton therapy (vs. 4,95/3,88 Gy with HT and vs. 5,56/3,58 Gy with CRT). Proton therapy best limited lower doses (V4Gy and V10Gy) compared to CRT, while HT could limit the higher doses (V20Gy) at the expense of larger volume irradiated at low doses (V4Gy). Conclusion Relative reduction in mean doses to the left and right breasts was of 50 and 57% respectively with proton therapy compared to CRT. Relation between radiation dose and SBC seems to be linear, and reduction in SBC should be in such proportion with proton therapy. Proton therapy seems highly interesting for breast sparing after curative treatment for HL, but these results need to be confirmed by individualized risk estimations and prospective trials. Citation Format: Samy R Horn, Victor Pernin, Nathalie Fournier-Bidoz, Youlia Kirova. Can proton therapy for localized mediastinal Hodgkin's lymphoma reduce second breast cancer incidence? [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-09-08.