Dosimetric and Clinical Predictors for RT-induced Esophageal Injury

Ahn, Sung Ja; Kahn, Danniel; Zhou, Sumin; Yu, Xiaoli; Hollis, Donna; Shafman, Timothy D; Marks, Lawrence B

Abstract

PURPOSE : To evaluate clinical and three dimensional (3D) dosimetric parameters associated with esophageal injury after radiotherapy for non-small cell lung cancer (NSCLC).
MATERIALS AND METHODS
: The records of 254 patients treated for NSCLC between 1992 and 2001 were reviewed. A variety of metrics describing the esophageal dose were extracted. Chemotherapy was given in 143 patients (56%). The RTOG toxicity criteria for grading of esophageal injury were used. The median follow-up time of all patients was 43 months with the range of 0.5~120 months. Logistic regression, contingency table analyses and Fisher's exact tests were used for statistical analysis.
RESULTS
: Acute toxicity occurred in 78% patients (199/254); grade 1,138; grade 2, 38; grade 3, 22 and grade 4, 1. For acute toxicity> or =Grade 2, BID-RT, age, nodal stage> or =N2, and most dosimetric parameters were predictive. Late toxicity occurred in 17 (7%) of 238 patients; grade 1, 5; grade 2, 4; grade 3, 5 and grade 4, 3. The median and maximum time to onset of late toxicity was 5 and 40 months after radiotherapy, respectively. Late toxicity occurred in 2%, 3%, 17%, 26%, and 100% of patients with acute grade 0, 1, 2, 3 and 4 toxicity, respectively. For late toxicity, the severity of acute toxicity was most predictive.
CONCLUSION
: A variety of dosimetric parameters are predictive for acute and late esophageal injury. A strong correlation between the dosimetric parameters prevented a comparison between the predictive abilities of these metrics. The presence of acute injury was the most predictive factor for the development of late injury. This suggests that late injury may be "consequential" and that aggressive treatment of acute effects may reduce the risk of late injury. Additional studies to better define predictors of RT-induced esophageal injury are needed