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P1.03 - Poster Session/ Treatment of Locoregional Disease – NSCLC (ID 212)
- Event: WCLC 2015
- Type: Poster
- Track: Treatment of Locoregional Disease – NSCLC
- Presentations: 1
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
P1.03-017 - Radiation Dose-Related Lymphopenia as an Outcome Predictor in Stage III NSCLC Patients Treated with Chemoradiation (ID 2918)
09:30 - 17:00 | Author(s): W. Barrett
RTOG 0617 failed to show survival advantage from increased radiation dose in stage III concurrent chemo radiation-treated patients. While toxicity was not significantly different between standard and high dose radiation groups, local-regional control and survival were inferior in high dose, experimental arm. These findings have largely remained unexplained. There is increased evidence in literature suggesting survival disadvantage associated with lymphopenia in certain malignancies. We hypothesize radiation-induced lymphopenia may be dose-dependent and may carry a survival disadvantage.
Stage III NSCLC patients treated with curative chemoradiation were retrospectively studied. Patients were categorized into those receiving standard dose and those receieiving high dose ( > 66Gy). Hematologic values including absolute lymphocyte count (ALC) was evaluated at diagnosis and at regular intervals during and after treatnent. Numerical variables were summarized using median (range) and compared between groups using non parametric Wilcoxon rank sum tests. Overall survival (OS) and other time to event endpoints were assessed using Kaplan-Meier (K-M) survival curves and compared between standard and high dose groups using log rank tests.
182 patients with stage III NSCLC were identified. 77 % male, 52% adenocarcinoma, and 41% squamous cell carcinoma. 155 patients received SD RT and 27 received HD RT. Pre-treatment ALC were not different between Standard and High dose groups [ 1730 /ul vs. 2065/ul (p=0.4955) ]. The High dose group showed lower Nadir ALC ( 279/ul vs 324/ul and shorter time to Nadir ( 29 d vs 35 d) than the Standar group ( two sided p’s =0.11and 0.06, and one sided p’s=0.05, 0.03 respectively). The K–M survival curves showed that Standard dose group has better OS than the High dose group (31.3 m vs 11.4 m , p<0.001). For patients whose Nadir ALC >600 (about 80% percentile level of Nadir ALC), median survival was 37.8 month as compared to 18.2 month among those Nadir ALC≤600 (p=0.192).
Our study showed sutrvival among patients treated with higher dose radiation was significantly worse. Although baseline absulte lymphocyte counts were not different between the two groups, patient treated with high dose radiation reached their nadir counts more quickly and also developed a lower absolute lymphocyte count compared to patients treated with standard dose. Regardless of treatment group, there was a trend towards a worse survival among patients who developed lower lymphocyte counts subsequent to traetment.