TY - JOUR

T1 - Joint Estimation of Cardiac Toxicity and Recurrence Risks After Comprehensive Nodal Photon Versus Proton Therapy for Breast Cancer

AU - Stick, Line B

AU - Yu, Jen

AU - Maraldo, Maja V

AU - Aznar, Marianne C

AU - Pedersen, Anders N

AU - Bentzen, Søren M

AU - Vogelius, Ivan R

N1 - Copyright © 2016. Published by Elsevier Inc.

PY - 2017/3/15

Y1 - 2017/3/15

N2 - PURPOSE: The study aims to perform joint estimation of the risk of recurrence caused by inadequate radiation dose coverage of lymph node targets and the risk of cardiac toxicity caused by radiation exposure to the heart. Delivered photon plans are compared with realistic proton plans, thereby providing evidence-based estimates of the heterogeneity of treatment effects in consecutive cases for the 2 radiation treatment modalities.METHODS AND MATERIALS: Forty-one patients referred for postlumpectomy comprehensive nodal photon irradiation for left-sided breast cancer were included. Comparative proton plans were optimized by a spot scanning technique with single-field optimization from 2 en face beams. Cardiotoxicity risk was estimated with the model of Darby et al, and risk of recurrence following a compromise of lymph node coverage was estimated by a linear dose-response model fitted to the recurrence data from the recently published EORTC (European Organisation for Research and Treatment of Cancer) 22922/10925 and NCIC-CTG (National Cancer Institute of Canada Clinical Trials Group) MA.20 randomized controlled trials.RESULTS: Excess absolute risk of cardiac morbidity was small with photon therapy at an attained age of 80 years, with median values of 1.0% (range, 0.2%-2.9%) and 0.5% (range, 0.03%-1.0%) with and without cardiac risk factors, respectively, but even lower with proton therapy (0.13% [range, 0.02%-0.5%] and 0.06% [range, 0.004%-0.3%], respectively). The median estimated excess absolute risk of breast cancer recurrence after 10 years was 0.10% (range, 0.0%-0.9%) with photons and 0.02% (range, 0.0%-0.07%) with protons. The association between age of the patient and benefit from proton therapy was weak, almost non-existing (Spearman rank correlations of -0.15 and -0.30 with and without cardiac risk factors, respectively).CONCLUSIONS: Modern photon therapy yields limited risk of cardiac toxicity in most patients, but proton therapy can reduce the predicted risk of cardiac toxicity by up to 2.9% and the risk of breast cancer recurrence by 0.9% in individual patients. Predicted benefit correlates weakly with age. Combined assessment of the risk from cardiac exposure and inadequate target coverage is desirable for rational consideration of competing photon and proton therapy plans.

AB - PURPOSE: The study aims to perform joint estimation of the risk of recurrence caused by inadequate radiation dose coverage of lymph node targets and the risk of cardiac toxicity caused by radiation exposure to the heart. Delivered photon plans are compared with realistic proton plans, thereby providing evidence-based estimates of the heterogeneity of treatment effects in consecutive cases for the 2 radiation treatment modalities.METHODS AND MATERIALS: Forty-one patients referred for postlumpectomy comprehensive nodal photon irradiation for left-sided breast cancer were included. Comparative proton plans were optimized by a spot scanning technique with single-field optimization from 2 en face beams. Cardiotoxicity risk was estimated with the model of Darby et al, and risk of recurrence following a compromise of lymph node coverage was estimated by a linear dose-response model fitted to the recurrence data from the recently published EORTC (European Organisation for Research and Treatment of Cancer) 22922/10925 and NCIC-CTG (National Cancer Institute of Canada Clinical Trials Group) MA.20 randomized controlled trials.RESULTS: Excess absolute risk of cardiac morbidity was small with photon therapy at an attained age of 80 years, with median values of 1.0% (range, 0.2%-2.9%) and 0.5% (range, 0.03%-1.0%) with and without cardiac risk factors, respectively, but even lower with proton therapy (0.13% [range, 0.02%-0.5%] and 0.06% [range, 0.004%-0.3%], respectively). The median estimated excess absolute risk of breast cancer recurrence after 10 years was 0.10% (range, 0.0%-0.9%) with photons and 0.02% (range, 0.0%-0.07%) with protons. The association between age of the patient and benefit from proton therapy was weak, almost non-existing (Spearman rank correlations of -0.15 and -0.30 with and without cardiac risk factors, respectively).CONCLUSIONS: Modern photon therapy yields limited risk of cardiac toxicity in most patients, but proton therapy can reduce the predicted risk of cardiac toxicity by up to 2.9% and the risk of breast cancer recurrence by 0.9% in individual patients. Predicted benefit correlates weakly with age. Combined assessment of the risk from cardiac exposure and inadequate target coverage is desirable for rational consideration of competing photon and proton therapy plans.

KW - Adult

KW - Aged

KW - Aged, 80 and over

KW - Breast Neoplasms

KW - Causality

KW - Comorbidity

KW - Disease-Free Survival

KW - Female

KW - Heart Diseases

KW - Humans

KW - Lymphatic Metastasis

KW - Middle Aged

KW - Neoplasm Recurrence, Local

KW - Proportional Hazards Models

KW - Proton Therapy

KW - Radiation Injuries

KW - Radiotherapy Dosage

KW - Radiotherapy Planning, Computer-Assisted

KW - Risk Assessment

KW - Risk Factors

KW - Sentinel Lymph Node

KW - Survival Rate

KW - Comparative Study

KW - Journal Article

U2 - 10.1016/j.ijrobp.2016.12.008

DO - 10.1016/j.ijrobp.2016.12.008

M3 - Journal article

C2 - 28244411

VL - 97

SP - 754

EP - 761

JO - International Journal of Radiation Oncology, Biology, Physics

JF - International Journal of Radiation Oncology, Biology, Physics

SN - 0360-3016

IS - 4

ER -