Radiation-induced Pulmonary Toxicity following Adjuvant Radiotherapy for Breast Cancer

Moon, Sung Ho; Kim, Tae Jung; Eom, Keun Young; Kim, Jee Hyun; Kim, Sung Won; Kim, Jae Sung; Kim, In Ah

Abstract

PURPOSE: To evaluate the incidences and potential predictive factors for symptomatic radiation pneumonitis (SRP) and radiographic pulmonary toxicity (RPT) following adjuvant radiotherapy (RT) for patients with breast cancer. A particular focus was made to correlate RPT with the dose volume histogram (DVH) parameters based on three-dimensional RT planning (3D-RTP) data.
MATERIALS AND METHODS
From September 2003 through February 2006, 171 patients with breast cancer were treated with adjuvant RT following breast surgery. A radiation dose of 50.4 Gy was delivered with tangential photon fields on the whole breast or chest wall. A single anterior oblique photon field for supraclavicular (SCL) nodes was added if indicated. Serial follow-up chest radiographs were reviewed by a chest radiologist. Radiation Therapy Oncology Group (RTOG) toxicity criteria were used for grading SRP and a modified World Health Organization (WHO) grading system was used to evaluate RPT. The overall percentage of the ipsilateral lung volume that received > or =15 Gy (V15), 20 Gy (V20), and 30 Gy (V30) and the mean lung dose (MLD) were calculated. We divided the ipsilateral lung into two territories, and defined separate DVH parameters, i.e., V15 TNGT, V20 TNGT, V30 TNGT, MLD TNGT, and V15 SCL, V20 SCL, V 30SCL, MLD SCL to assess the relationship between these parameters and RPT.
RESULTS
Four patients (2.1%) developed SRP (three with grade 3 and one with grade 2, respectively). There was no significant association of SRP with clinical parameters such as, age, pre-existing lung disease, smoking, chemotherapy, hormonal therapy and regional RT. When 137 patients treated with 3D-RTP were evaluated, 13.9% developed RPT in the tangent (TNGT) territory and 49.2% of 59 patients with regional RT developed RPT in the SCL territory. Regional RT (p<0.001) and age (p=0.039) was significantly correlated with RPT. All DVH parameters except for V15 TNGT showed a significant correlation with RPT (p<0.05). MLDTNGT was a better predictor for RPT for the TNGT territory than V15 SCL for the SCL territory.
CONCLUSION
The incidence of SRP was acceptable with the RT technique that was used. Age and regional RT were significant factors to predict RPT. The DVH parameter was good predictor for RPT for the SCL territory while MLD TNGT was a better predictor for RPT for the TNGT territory.