Radiation and Cancer Physics

SS 27 - Physics 7 - Special Session: Outcome Analysis and Modeling

193 - Dosimetric Predictors for Radiation Induced Esophagitis in Patients with Lung Cancer Treated With Concurrent Chemoradiation

Tuesday, October 23
3:15 PM - 3:25 PM
Location: Room 214 C/D

Dosimetric Predictors for Radiation Induced Esophagitis in Patients with Lung Cancer Treated With Concurrent Chemoradiation
R. He1, E. Hamadain2, S. Packianathan1, M. R. Kanakamedala1, S. Vijayakumar1, and C. C. Yang1; 1Radiation Oncology, University of Mississippi Medical Center, Jackson, MS, 2Diagnostic and Clinical Health Sciences, University of Mississippi Medical Center, Jackson, MS

Purpose/Objective(s): To identify the dosimetric parameters which predict esophagitis in lung cancer patients treated with concurrent chemo-radiation using “Low-Modulated” Intensity Modulated Radiation Therapy (LM-IMRT). A LM-IMRT treatment plan uses a sparsely IMRT technique generated by limiting the degree of modulation, the number of segments per beam, and the segment size during the inverse planning process to minimize the unpredictable interplay between lung tumor motion and small segment multi-leaf collimator (MLC) movements.

Materials/Methods: The hypothesis of this retrospective and single institution study is that the acute esophagitis was related to the dose-volume parameters, and the dose-volume parameters could be dosimetric predictors of acute esophagitis. In this study, the treatment charts of 139 lung cancer patients treated with the LM-IMRT technique with concurrent chemo-radiotherapy were reviewed. The mean esophagus dose (MED), dose-volume parameters Vx (Vx = percentage esophageal volume receiving ≥ x Gy), and the endpoints of esophagitis grade 1 and 2 (based on Radiation Therapy Oncology Group definitions) were derived from the Pinnacle treatment planning system and the EPIC electronic medical record system, respectively. Binary logistic regression and probit statistical analysis were used to determine the relationships between grade 1 and 2 esophagitis, and MED and Vx. All the statistical analyses were performed using IBM SPSS software version 24. All statistical tests of significance were performed at the 5% significant level (α=0.05).

Results: Various Vx (V5, 10, 15, 20, 30, 40, 50 and 60) and MED were significantly associated with the probability of esophagitis. The probability of grade 1 and 2 esophagitis increased with increasing values of Vx and MED. V20, V30, V40, and V50 were statistical significant dosimetric predictors of radiation induced grade 1 esophagitis (p<0.05). The MED associated with a 50% probability (TD50) of grade 1 and 2 esophagitis were determined to be 15.1 Gy and 45.9 Gy, respectively. The parameters of the Lyman-Kutcher-Burman model, n, m and TD50, were fitted and compared with published findings. Table: LKB model parameter comparison to previous results
Investigator TD50 (Gy) n m
Burman et al., 1991 68 0.06 0.11
Chapet et al., 2005 (Esophagitis Grade 2 or Greater) 51 (20-82) 0.44 (0.11-0.41) 0.32 (0.19-0.57)
Belderbos et al., 2005 (Esophagitis Grade 2 or Greater) 47 (45-60) 0.69 (0.18-6.3) 0.36 (0.25-0.53)
This study (Esophagitis Grade 1) LM-IMRT 15.1 (10.6-19.6) 1 0.17
This study (Esophagitis Grade 2) LM-IMRT 45.9( 33.9-71.4) 1 0.08

Conclusion: Our results suggest that MED, V20, V30, V40, and V50 may be good predictors of the risk of radiation-induced esophagitis. The TD50 of grade 1 and 2 esophagitis were determined using the predictive model established in this study. Our findings can be used as additional clinical guidelines in treatment planning and plan evaluation, as well as in discussing the risk of esophagitis when obtaining informed consent.

Author Disclosure: R. He: None. E. Hamadain: None. S. Packianathan: None. M.R. Kanakamedala: None. S. Vijayakumar: None. C. Yang: None.

Rui He, PhD

Disclosure:
No relationships to disclose.

Presentation(s):

Send Email for Rui He


Assets

193 - Dosimetric Predictors for Radiation Induced Esophagitis in Patients with Lung Cancer Treated With Concurrent Chemoradiation

Slides

Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Dosimetric Predictors for Radiation Induced Esophagitis in Patients with Lung Cancer Treated With Concurrent Chemoradiation