(P117) Anatomical Variations and Radiation Technique for Breast Cancer

OncologyOncology Vol 28 No 1S
Volume 28
Issue 1S

Conventional radiotherapy (RT) with proton-based RT in a series of patients with right- or left-sided breast cancer and anatomical variations resulting in technically challenging radiation plans are compared.

P117: Figure A

P117: Figure B

Julie A. Bradley, MD, Meng Wei Ho, MSc, Roi Dagan, MD, Nancy P. Mendenhall, MD; University of Florida Proton Therapy Institute

Purpose: To compare conventional radiotherapy (RT) with proton-based RT in a series of patients with right- or left-sided breast cancer and anatomical variations resulting in technically challenging radiation plans.

Methods: Eight women had conventional (photon and/or electron) and proton-based (proton only or combined photon-proton) radiation plans developed. Four were treated with the conventional plan, and four were treated with the proton-based plan. Cardiac V5, V20, and V50; mean heart dose; and ipsilateral lung V5 and V20 were documented for each plan, along with D95 to the breast or chest wall and regional lymphatics (supraclavicular, level I–III axilla, and internal mammary chain [IMC]). All plans were optimized to achieve adequate target coverage.

Results: Dose-volume constraints were difficult to meet with conventional radiation in three patients with right-sided breast cancer because of significant breast ptosis (n = 2) or bilateral implants (n = 1). For two of the three patients, IMC irradiation was omitted in order to meet the lung V20 constraint. In these three patients, ipsilateral lung V20 with a conventional plan treating the IMC ranged from 44.7% to 47.5%. The lung V20 was decreased by adding a proton component to the plan, with lung V20 ranging from 14.4% to 26.1%. The mean heart dose ranged from 1.7–4.3 Gy for the conventional plans compared with 0.6–0.8 Gy for the proton-based plans. In the five patients with left-sided disease, constraints were difficult to meet in the two postmastectomy patients with a chest wall too thick or too variable in depth for electrons only, in one patient with large breasts and significant ptosis, in one patient with a heart-shaped thorax, and in one patient with severe arthritis limiting upper-extremity extension. In these five patients, the mean heart dose ranged from 6–19 Gy for the conventional plans compared with 0.8–2.9 Gy for the proton-based plans. In the conventional plans, ipsilateral lung V20 ranged from 40% to 46% compared with 9.8% to 31.6% with the proton-based plans. Cardiac V5 and lung V5 were reduced for both right- and left-sided disease treated with proton-based RT (mean cardiac V5 right: 15% vs 1.3%; mean lung V5 right: 75% vs 40%; mean cardiac V5 left: 29% vs 5%; mean lung V5 left: 58% vs 32% for conventional vs proton radiotherapy, respectively). In addition, for left-sided breast cancers, a decrease in cardiac V20 and V50 was seen with the proton-based plans (mean cardiac V20: 18% vs 2% and mean cardiac V50: 5.5% vs 1.5% for conventional vs proton radiotherapy, respectively).

Conclusion: Proton-based RT decreases the heart and lung doses for both left- and right-sided breast cancer patients with unfavorable anatomy, such as implants, large breasts, a heart-shaped thorax, and limited upper-extremity range of motion. In these cases, proton-based RT allows adequate target coverage and goal organ-at-risk constraints to be achieved simultaneously.

Articles in this issue

(P113) Age and Marital Status Are Associated With Choice of Mastectomy in Patients Eligible for Breast Conservation Therapy
(P112) Single-Institution Experience With Intrabeam IORT for Treatment of Early-Stage Breast Cancer
(P110) Breast Cancer Before Age 40: Current Patterns in Clinical Presentation and Local Management
(P111) Accelerated Partial-Breast Irradiation With Multicatheter High-Dose-Rate Brachytherapy: Feasibility and Results in a Private Practice Cohort
(P115) Breast Cancer Laterality Does Not Influence Overall Survival in a Large Modern Cohort: Implications for Radiation-Related Cardiac Mortality
(P117) Anatomical Variations and Radiation Technique for Breast Cancer
(P116) Bilateral Immediate DIEP Reconstruction and Postmastectomy Radiotherapy: Experience at a Tertiary Care Institution
(P118) Metadherin Overexpression Is Associated With Improved Locoregional Control After Mastectomy
(P119) Effect of Economic Environment on Use of Postlumpectomy Radiation Therapy for Stage I Breast Cancer
(P120) Immediate Versus Delayed Reconstruction After Mastectomy in the United States Medicare Breast Cancer Patient
(P121) Trend in Age and Racial Disparities in the Receipt of Postlumpectomy Radiation Therapy for Stage I Breast Cancer: 2004–2009
(P122) Streamlining Referring Physicians Orders With ‘Reflex Testing’ Significantly Decreases Time to Resolution for Abnormal Screening Mammograms
(P123) National Trends in the Local Management of Early-Stage Paget Disease of the Breast
(P124) Effect of Inhomogeneity on Cardiac and Lung Dose in Partial-Breast Irradiation Using HDR Brachytherapy
(P125) Breast Cancer Outcomes With Anthracycline-Based Chemotherapy for Residual Disease Burden After Full-Dose Neoadjuvant Chemotherapy and Surgery Followed by Radiation Treatment
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