ESTRO 2021 Abstract Book

S682

ESTRO 2021

Tumor match and ART reduced the irradiated volumes of lungs and heart, hereby decreasing RP, while maintaining loco-regional control. Thus, the precision of radiotherapy was safely improved and the risk of pulmonary toxicity reduced. Further, we observed a significantly improved overall survival, in part because lethal RP was reduced. PD-0847 Dose escalation in locally advanced NSCLC: comparing outcomes in adenocarcinoma and squamous cell carcinoma S. Abel 1 , P. Renz 1 , A. Colonias 1 , M. Raj 2 , R. Wegner 1 1 Allegheny Health Network Cancer Institute, Radiation Oncology, Pittsburgh, USA; 2 Allegheny Health Network Cancer Institute, Medical Oncology, Pittsburgh, USA Purpose or Objective Standard management of locally advanced, unresectable non-small cell lung carcinoma (NSCLC) is definitive chemoradiotherapy (CRT) succeeded by consolidative immunotherapy. A heterogeneous disease, the two most common NSCLC histologies include squamous cell carcinoma (SCC) and adenocarcinoma (ADC). Emerging data suggests a differential histologic-based dose response in early stage NSCLC receiving radiotherapy; however whether this finding is consistent in locally advanced disease is unclear. As such, we performed an analysis of the National Cancer Database (NCDB) to compare outcomes and identify predictors of treatment receipt in patients with locally advanced ADC and SCC of the lung, treated with standard dose (60 Gy) and dose We queried the NCDB for patients diagnosed with Stage III ADC or SCC of the lung between the years 2004 – 2015 who were treated non-surgically with concurrent CRT to a definitive dose of 60 Gy (standard dose) or 74 Gy (dose escalated treatment). Univariable and multivariable analyses identified characteristics predictive of overall survival. Overall survival (OS) was calculated from the date of diagnosis to the date of last contact or death using Kaplan Meier curves to present the cumulative probability of survival, and log-rank statistics were used to assess statistical significance between groups. Multivariable logistic regression was performed to identify clinicopathologic variables associated with dose escalated treatment. Results Ultimately 4,565 Stage III NSCLC patients with either SCC (n=2,422) or ADC (n=2,143) were eligible for analysis, of which, 146 SCC and 116 ADC patients received dose escalated CRT. In patients with SCC, univariable analysis demonstrated a median overall survival of 20 months (standard dose) vs 23 months (dose escalation) with 1 year (68% vs 72%), 3 year (31% vs 35%), and 5 year (19% vs 22%) OS rates for standard dose and dose escalation respectively (p = NS). In patients with ADC, median overall survival was 24 months (standard dose) vs 31 months (dose escalation), with 1 year (73% vs 79%), 3 year (35% vs 46%), and 5 year (18% vs 28%) OS rates for standard dose and dose escalation respectively (p = 0.01). Predictors of dose escalated CRT receipt include: use of IMRT (OR: 1.56, 95% CI: 1.21-2.03), absence of N3 disease (OR: 2.28, 95% CI: 1.30- 4.01), and male sex (OR: 1.31, 95% CI: 1.01-1.70). Conclusion Dose escalated CRT was associated with improved OS in Stage III NSCLC patients with ADC histology compared to standard dose treatment. This association was not evident in patients with SCC, potentially suggesting a histologic differential treatment response. Although hypothesis generating, this finding warrants prospective validation considering the inherent limitations of this retrospective study. escalated (74 Gy) CRT. Materials and Methods PD-0848 Stereotactic body radiotherapy for poor surgical candidates with primary renal cell carcinoma Y.Y. Jo 1 1 Asan Medical Center, Radiation Oncology , Seoul , Korea Republic of Purpose or Objective Stereotactic body radiotherapy (SBRT) has considerable advantages including its ability to provide a non- invasive ablative treatment with very few treatment sessions, with emerging evidence showing promising rates of local control (LC). Therefore, it might be an alternative curative treatment strategy for patients who are unfit for radical surgery. This prospective study was performed to assess the feasibility and safety of SBRT for renal cell carcinoma (RCC). Materials and Methods This protocol is a single arm, single-institutional phase II study. 40 patients will be recruited from 2016 and followed for a total of 2 years. preliminary report completed a minimum of 12 months follow up 17 persons. All patients had T1a(≤4cm) diseases. Median patient age was 78 years and all patients had Charlson comorbidity score≤8. Median tumor size was 24mm at Diagnosis CT and 25mm at Planning CT. A total of 42 Gy in 3 fractions was delivered every other day using Cyberknife system. The tumor sizes and serum creatinine also GFR were compared between the pre-treatment assessment and subsequent postRT 3 month, 12 month assessment. Tumor response was assessed by imaging results using Response Evaluation Criteria In Solid Tumors (RECIST v1.1) measurement. Toxicities were recorded using Common Terminology Criteria for Adverse Events V5.0. Results In total, 14 patients were included to analyze so far. We evaluated post RT 3 month radiographic response and finally post RT 1 year response, one(7%) patient achieved complete response at 1yr follow up, six (43%) had partial responses, seven (50%) had stable disease and none had progressive disease, indicating a local control rate of 100%. Two patients had grade 2 acute nausea and only one patient had grade 3 renal toxicity who had history of radical nephrectomy of opposite side kidney because of RCC. And there were No grade 4-5 toxicities were Poster discussions: Poster Discussion 21: Urology - non prostate