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A. Sun
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MA 09 - The Current Status of Radiation Oncology (ID 666)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Locally Advanced NSCLC
- Presentations: 1
- Moderators:Tomoki Kimura, Yong Chan Ahn
- Coordinates: 10/17/2017, 11:00 - 12:30, Room 316
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MA 09.02 - Ultra-Central Tumours Treated with Stereotactic Body Radiotherapy: A Single Institutional Experience (ID 8758)
11:05 - 11:10 | Author(s): A. Sun
- Abstract
- Presentation
Background:
Stereotactic body radiotherapy of “ultra-central” (UC) lung tumours, PTV directly abuts/overlaps the proximal bronchial tree (PBT), trachea, esophagus, pulmonary vein/artery, are considered to be at higher risk of toxicity. The purpose of this study is to review the outcomes and toxicities of Ultra-central lung tumours, compared to central tumours.
Method:
A retrospective review based on a prospective database of patients treated with lung SBRT from January 2006- December 2015 was conducted. Patients with central tumours defined using RTOG 0813 criteria and ultracentral tumours were included. 115 patients (53%) received 60Gy/8 and 61 (28%) received 48Gy/4. At our institution, the recommended Dmax for esophagus is 45Gy and 40Gy for 8 and 4 fractions, respectively. The Dmax and D10cc constraints for trachea, proximal bronchial tree, heart, and major vessels (including pulmonary artery and vein) are 48Gy and 40Gy for 4 fractions and 64 and 60Gy for 8 fractions. Toxicity was graded using CTCAE v3.0. Log-rank test was used to compare overall and cause-specific survival. Local, regional, and distant recurrence were compared using Gray’s test.
Result:
215 tumours were analyzed (189 C and 26 UC). The median age for C and UC were 75 years and 72.5 years. Median tumour size and PTV volume were 2.2 cm (range 0.9-5.7) and 41.7 cm3 (range 9.7-246.3) (C group) and 2.5 cm (0.8-5.5) and 58.2 cm3 (16.8-238.3) (UC group). The percentage of squamous cell carcinoma was higher in the UC group (15%, n=29 in C; 38%, n=10 in UC). The median follow-up was 20.3 months (24.5 mo for patients still alive). Median overall survival (OS) and cause-specific survival (CSS) was 34 mo and 53.8 mo for C and 20.1 mo and 28.2 mo for UC, respectively. Differences in OS and CSS between the two groups did not meet statistical significance (p=0.24 and p=0.14, respectively). Local, regional, and distant failure rates were 3%, 8% and 18% in the central tumour group and 0%, 9% and 25% in the ultra-central tumour group at 2 years. There was no statistically significant difference found in the rates of recurrence between the two groups. The rates of any grade 2 or higher toxicity (hemoptysis, esophageal toxicity, cough, dyspnea, pneumonitis) was 9% (n=17) in the C and 7.7% (n=2) in UC group (p=0.89). There were no known grade 4 or 5 toxicities.
Conclusion:
In our experience, SBRT to ultra-central tumours resulted in effective local control and no excessive risk of toxicity compared to central tumours.
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P1.14 - Radiotherapy (ID 700)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P1.14-016 - Assessing the Feasibility of FLT-PET for Evaluation of Non-Small Cell Lung Cancer (NSCLC) Treated with Stereotactic Body Radiotherapy (SBRT) (ID 8455)
09:30 - 09:30 | Author(s): A. Sun
- Abstract
Background:
Distinguishing fibrosis from tumor recurrence following lung SBRT remains a clinical challenge since CT has poor sensitivity and specificity for detecting recurrence. 18F-Fluoro-L-thymidine-PET (FLT-PET) uptake correlates with cell proliferation. The purpose of this study is to investigate the feasibility of FLT-PET as an imaging biomarker for lung SBRT response assessment.
Method:
In this prospective study, three groups were included: 1) newly-diagnosed biopsy-proven NSCLC pre-SBRT, 2) established post-SBRT mass-like fibrosis on serial follow-up CT scans by co-investigators’ consensus, and 3) biopsy-proven locally-recurrent NSCLC after SBRT. Non-gated, helical gated (3D-CT/4D-PET) and phase-matched (4D-CT/4D-PET) FLT-PET images were obtained. Group-1 underwent fluorodeoxyglucose (FDG)-PET scan according to clinical guidelines. FLT uptake was measured by SUV95 and SUV50 (95% and 50% of maximum pixel value plus average background value, respectively), SUV2Dpeak and SUV3Dpeak (1cm diameter circular or spherical around region of interest, respectively), SUVmean and SUVmax. Descriptive statistics were gathered. Kolmogorov–Smirnov test was used to determine normality. Statistical significance was reported using student’s t-test.
Result:
27 patients were included, with 19 primary tumors (group-1), 12 established fibrosis (group-2) and 1 recurrence (group-3). In group-1, 16 tumors were T1. Group-1, mean FDG-PET SUVmax, SUV95, SUV50, SUV2Dpeak, SUV3Dpeak and SUVmean were 7.40, 5.88, 2.39, 5.59, 6.02 and 2.78, respectively. Mean FLT-PET values for group-1 were 3.43, 2.84, 1.71, 2.9, 2.82 and 1.78, respectively. Group-2 SBRT dose was either 48Gy in 4 fractions (83%) or 60Gy in 8 fractions. Median time from radiation to FLT-PET scan in group-2 was 19.5 months (5.8-83.8mos). The patient in group-3 had SUV50, SUV95, SUV2Dpeak, SUV3Dpeak, SUVmean and SUVmax of 2.27, 3.85, 6.37, 6.05, 2.39 and 7.64, respectively. Mean FLT-PET SUVmax for groups 1 and 2 was significantly different (p=0.03) at 3.42(1.14-7.04) and 2.34(1.23-4.35) respectively. Similarly, mean (range) of SUV50, SUV95 and SUVmean for group-1 was 1.8(0.74-3.43), 2.97(1.03-5.83), 1.87(0.73-3.44), and for group-2 was 1.22(0.81-2.26), 1.85(1.13-3.8) and 1.25(0.83-2.39), respectively (p<0.01, <0.01 and <0.01). There was no statistically-significant difference between SUV2Dpeak and SUV3Dpeak between groups 1 and 2, with a mean of 2.97(0.99-6.30) and 2.91(0.90-6.11) for group-1 and 2.10(1.11-3.91) and 2.03(1.00-3.86) for group-2 (p=0.06 and 0.06), respectively. There was no statistically significant difference between the 3D and 4D image acquisition in group-1. There were no FLT-PET-related toxicities.
Conclusion:
FLT-PET is feasible in SBRT patients pre- and post-treatment, and may assist in distinguishing fibrosis from recurrent tumor. Further validation studies are needed.
