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Kyle Verdecchia



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    MA01 - Early Stage Lung Cancer: Questions and Controversies (ID 894)

    • Event: WCLC 2018
    • Type: Mini Oral Abstract Session
    • Track: Treatment of Early Stage/Localized Disease
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/24/2018, 10:30 - 12:00, Room 202 BD
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      MA01.07 - Validation of RTOG 0813 Normal Tissue Constraints for Pulmonary Toxicity in SBRT for Central Non-Small Cell Lung Cancer (ID 11318)

      11:10 - 11:15  |  Presenting Author(s): Kyle Verdecchia

      • Abstract
      • Presentation
      • Slides

      Background

      Stereotactic body radiation therapy (SBRT) yields excellent local control rates for medically inoperable early stage "central" non-small cell lung cancer. Normal tissue constraints provided in RTOG 0813, which tested safety and efficacy of lung SBRT for central tumors, were largely based on expert estimates, and clinical validation of constraints is limited. We sought to identify the sensitivity and specificity of the current RTOG constraints for predicting pulmonary toxicity in a large institutional data set.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We identified 136 lesions within 2 cm of the proximal bronchial tree (PBT), treated from 2005 to 2014 from a prospective registry of 1,462 patients. Dose was 50 or 60 Gy given in 5 fractions. Pulmonary toxicity was categorized as pneumonitis or non-pneumonitis (fistula, bronchial stenosis or necrosis, atelectasis, hemoptysis, or clinically significant pleural effusion). A series of dose endpoints for the PBT was generated based on dose volume histograms, where dose levels ranged from 0 Gy to 80 Gy in increments of 0.1 Gy, and volumes ranged from 0.03 cc to 50 cc in increments of 0.03cc. A total of 1,333,600 dosimetric endpoints were analyzed. The sensitivity and specificity of these endpoints in predicting pulmonary toxicity was calculated. The optimal dosimetric endpoint was chosen by identifying the highest F-score.

      4c3880bb027f159e801041b1021e88e8 Result

      We observed nine Grade 2 pneumonitis and 10 Grade ≥ 2 non-pneumonitis toxicities, of which three were Grade 5 (broncho-pleural fistula, left mainstem bronchus necrosis, and bronchial stenosis). The optimal dosimetric endpoint to avoid Grade 2-5 non-pneumonitis toxicity was D0.03cc<50 Gy to the PBT, with 90% sensitivity and 77% specificity. The optimal point dose to avoid Grade 3-5 non-pneumonitis toxicity was D0.3cc<46.5 Gy, with 100% sensitivity and 85% specificity. Applying PBT RTOG constraints to our dataset achieved 18% sensitivity and 91% specificity for D4cc<18 Gy and 29% sensitivity and 93% specificity for D0.03cc<52.5 Gy.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Clinical results from this large institutional data set validate current RTOG constraints for PBT as predictive for pulmonary toxicity. The results also suggest that RTOG constraints D4cc<18 Gy and D0.03cc<52.5 Gy to PBT have moderate sensitivity but excellent specificity for pulmonary toxicity. We identified D0.03cc <50 Gy to PBT as having the largest sensitivity and specificity for toxicity prediction, and this value parallels current RTOG constraint of D0.03cc <52.5 Gy. This analysis suggests that an additional volume/dosimetric constraint of D0.3cc<46.5 Gy may be considered for avoidance of Grade 3-5 non-pneumonitis pulmonary toxicity.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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    P1.16 - Treatment of Early Stage/Localized Disease (Not CME Accredited Session) (ID 948)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 2
    • Moderators:
    • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
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      P1.16-24 - Impact of Tumor Location &amp; Dosimetric Predictors for Chest Wall Toxicity in Single Fraction SBRT for Stage I Non-Small Cell Lung Cancer (ID 11317)

      16:45 - 18:00  |  Author(s): Kyle Verdecchia

      • Abstract
      • Slides

      Background

      Single fraction stereotactic body radiation therapy (SF-SBRT) is an acceptable regimen for treatment of peripheral Stage I Non-Small Cell Lung Cancer (NSCLC). Rates of chest wall toxicity (CWT) are not stratified by distance of tumor to chest wall (CW) and dosimetric parameters are not well defined. We sought to determine the relationship of tumor location and dosimetric parameters with CWT in SF-SBRT.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      An IRB-approved prospective SBRT registry of 1,462 patients (pts) was used to identify pts treated with 30 Gy or 34 Gy in one fraction. Tumors were ≤ 5 cm, node-negative, and ≥ 2 cm from the proximal tracheo-bronchial tree. The CW was retrospectively contoured (3 cm soft-tissue structure). Gross tumor volume was measured as abutting, ≤ 1 cm, 1-2 cm or > 2 cm from the CW. CWT was graded according to CTCAE 3.0 criteria. Rates of CWT were compared using unpaired t-test. Logistic regression analysis was used to identify tumor and dosimetric parameters associated with CWT.

      4c3880bb027f159e801041b1021e88e8 Result

      This study included 146 lesions treated with SF-SBRT. Median follow-up was 23.8 months. There were 80 pts (55%) treated with 30 Gy and 66 pts (45%) treated with 34 Gy. The rate of CWT was 30.6% for lesions abutting CW, 8.2% for ≤ 1 cm from CW, 3.8% for 1-2 cm from CW, and 5.7% for > 2 cm from CW. Grade ≥ 3 CWT was modest (1.4%). Tumor abutment (OR 6.5; p=0.0005), BMI (OR 1.1; p= 0.02), rib D1cc (OR 1.01 per Gy; p= 0.03), CW D1cc (OR= 1.08 per Gy; p=0.03), and CW D5cc (OR 1.10 per Gy; p= 0.01) were significant predictors for CWT on univariate analysis. Tumor abutment was the only significant predictor for CWT (OR 7.5; p= 0.007) on multivariate analysis. CWT occurred in only 1 out of 40 pts with CW D5cc < 18 Gy, while our model suggested a 15% risk of CWT with D5cc of 27.2 Gy to CW.

      8eea62084ca7e541d918e823422bd82e Conclusion

      The rate of CWT is significantly associated with distance from the CW. When considering lesions adjacent to the CW, the rate of CWT in this series (30.6%) does not appear to exceed rates in the published fractionated SBRT literature (20-33%). Location adjacent to CW should not be a contraindication to SF-SBRT. CW D1cc and D5cc may be used as predictors of CWT rates. As most CWT is low-grade and self-limited, these dosimetric parameters should be utilized as a guideline, rather than an absolute constraint.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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      P1.16-27 - Using Rates of Clinical Brachial Plexopathy after Lung SBRT to Better Characterize the Tolerance of the Brachial Plexus (ID 12741)

      16:45 - 18:00  |  Presenting Author(s): Kyle Verdecchia

      • Abstract
      • Slides

      Background

      Treatment of apical lung tumors with stereotactic body radiation therapy (SBRT) can be challenging due to proximity to the brachial plexus (BP). We retrospectively investigated outcomes after treatment of apical lung tumors to compare the rate of brachial plexopathy (BPX) with what would be estimated based on published protocol-derived BP constraints.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      Apical lung tumors were defined in this analysis as those whose lung SBRT target had a planning-derived PTV edge <1cm from the anatomic BP. We surveyed an IRB-approved prospective registry of 1,462 patients treated with SBRT for the interval 2003-2017 and included all patients who received definitive or salvage SBRT using dose/fractionation schedules of 50 Gy/5 fx, 60 Gy/5 fx, or 48 Gy/4 fx. Salvage SBRT included patients with local recurrence after conventional fractionation radiotherapy. Per RTOG protocols, the subclavian vein (SCV) ipsilateral to target was contoured as the BP surrogate. In this study, the ipsilateral subclavian artery (SCA), and BP were also contoured to characterize dosimetric differences between structures. Statistical analysis involved repeated measures ANOVA.

      4c3880bb027f159e801041b1021e88e8 Result

      Sixty-four patients, which includes six patients (9.4%) receiving salvage SBRT, met inclusion criteria (median follow up of 21 months). No significant differences (p=0.77) were observed between maximum point doses to BP, SCV, and SCA. Within one year post-SBRT, two patients (3%) developed BPX (grade 2); both patients had exceeded 32 Gy to the BP and were treated with salvage SBRT. No patient treated with definitive SBRT (91%) developed BP, despite 17 of these exceeding recommended maximum doses.

      8eea62084ca7e541d918e823422bd82e Conclusion

      No BPX was observed for patients that exceeded a maximum dose of 32 Gy to the BP, unless they were treated as salvage SBRT. This suggests higher doses to the BP may be considered when clinically required for definitive SBRT. However, salvage SBRT may require more conservative BP constraints than used in the definitive setting.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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