Developing Multivariable Normal Tissue Complication Probability Model to Predict the Incidence of Symptomatic Radiation Pneumonitis among Breast Cancer Patients.

Tsair-Fwu Lee,Yu-Jie Huang,Liyun Chang,Hui-Min Ting,Pei-Ju Chao,Jian Jian Li

doi:10.1371/journal.pone.0131736

Abstract

PurposeSymptomatic radiation pneumonitis (SRP), which decreases quality of life (QoL), is the most common pulmonary complication in patients receiving breast irradiation. If it occurs, acute SRP usually develops 4–12 weeks after completion of radiotherapy and presents as a dry cough, dyspnea and low-grade fever. If the incidence of SRP is reduced, not only the QoL but also the compliance of breast cancer patients may be improved. Therefore, we investigated the incidence SRP in breast cancer patients after hybrid intensity modulated radiotherapy (IMRT) to find the risk factors, which may have important effects on the risk of radiation-induced complications.MethodsIn total, 93 patients with breast cancer were evaluated. The final endpoint for acute SRP was defined as those who had density changes together with symptoms, as measured using computed tomography. The risk factors for a multivariate normal tissue complication probability model of SRP were determined using the least absolute shrinkage and selection operator (LASSO) technique.ResultsFive risk factors were selected using LASSO: the percentage of the ipsilateral lung volume that received more than 20-Gy (IV20), energy, age, body mass index (BMI) and T stage. Positive associations were demonstrated among the incidence of SRP, IV20, and patient age. Energy, BMI and T stage showed a negative association with the incidence of SRP. Our analyses indicate that the risk of SPR following hybrid IMRT in elderly or low-BMI breast cancer patients is increased once the percentage of the ipsilateral lung volume receiving more than 20-Gy is controlled below a limitation.ConclusionsWe suggest to define a dose-volume percentage constraint of IV20< 37% (or AIV20< 310cc) for the irradiated ipsilateral lung in radiation therapy treatment planning to maintain the incidence of SPR below 20%, and pay attention to the sequelae especially in elderly or low-BMI breast cancer patients. (AIV20: the absolute ipsilateral lung volume that received more than 20 Gy (cc).

Highlights

Radiation therapy is the most effective adjuvant treatment in breast cancer after surgery [1,2,3]
Positive associations were demonstrated among the incidence of symptomatic Radiation pneumonitis (RP) (SRP), IV20, and patient age
body mass index (BMI) and T stage showed a negative association with the incidence of SRP

Summary

Introduction

Radiation therapy is the most effective adjuvant treatment in breast cancer after surgery [1,2,3]. Lungs, located beneath the breasts, are among the most critical organs in radiation therapy in the treatment planning for breast cancer. As the essential organ for respiration, reduction of lung damage during breast cancer radiotherapy is important. Radiation pneumonitis (RP), which decreases quality of life (QoL), is the most common pulmonary complication in patients receiving breast irradiation. If it occurs, acute RP usually develops 4–12 weeks after completion of radiotherapy and presents symptoms as a dry cough, dyspnea and low-grade fever [4, 5]. If the incidence of symptomatic RP (SRP) is reduced, the QoL and the compliance of breast cancer patients may be improved

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Conclusion