1. Evaluating a Nomogram for the Development of Radiation Pneumonitis in Locally Advanced Non-Small Cell Lung Cancer Treated with 3D and Intensity Modulated Radiation Therapy Sana Rehman, MD 1, Christina K. Speirs, MD, PhD 1, Alerson Molotievschi, MD 2, Daniel Mullen, DDS, MS 1, Sandra Fergus BS 1, Todd A. DeWees, PhD 1, Maria A. Velez 1, Jeffrey D. Bradley, MD 1, Cliff G. Robinson, MD 1, 1 Washington University in St. Louis, St. Louis, MO, 2 Barretos Cancer Hospital, Barretos, Brazil Session title: Lung 1 – Novel Prognostic Factors and SBRT ASTRO 2014 - #57012

2. Department of Radiation Oncology Purpose / Methods Purpose Evaluate a previously published nomogram on risk of developing radiation pneumonitis (RP) on a more modern cohort, including patients treated with intensity modulated radiation therapy (IMRT) Determine risk factors for development of grade 2 or higher RP Methods Retrospective analysis of 340 patients treated with radiation therapy for locally advanced non-small cell lung cancer at Siteman Cancer Center from 2001 to 2012. Clinical, tumor, and dosimetric information were collected. Univariate (UVA) and multivariate (MVA) analyses were used to correlate these factors with the development of ≥ grade 2 RP. RP risk was determined based on a nomogram prediction for RP. Spearman’s rank correlation was performed based on the calculated risk of RP versus the actual rate of RP.

3. Department of Radiation Oncology Results 111 patients (35%) developed grade 2 or higher RP at a median of 3.6 months (range, 0 – 21.9 mo). Factors predictive on UVA for grade 2 or higher RP included: Use of adjuvant chemotherapy Former smoking status Heart mean dose Heart V5-55 Gy (in 5 Gy increments) Total lung volume minus PTV V35-50 Gy (in 5 Gy increments) RP risk nomogram score On MVA, heart V35 Gy was predictive and current smoking status was protective of grade 2 or higher RP.

4. Department of Radiation Oncology Conclusion The dose to the heart is predictive for the risk of RP. The nomogram for predicting RP is validated for patients treated with 3DCRT. The nomogram was not validated for patients treated with IMRT.