Lung Cancer

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TU_33_3649 - Stereotactic Ablative Radiation Therapy Achieves Excellent Outcomes for Elderly Patients With Bulky Early-Stage Non Small-Cell Lung Cancer

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Stereotactic Ablative Radiation Therapy Achieves Excellent Outcomes for Elderly Patients With Bulky Early-Stage Non Small-Cell Lung Cancer
I. H. Sin1, B. S. H. Chia1, C. Yip1, W. L. Ng1, T. R. Siow1, A. Thiagarajan1, S. P. Yap2, K. W. Fong1, and K. L. M. Chua1; 1National Cancer Centre Singapore, Singapore, Singapore, 2National Cancer Centre, Singapore, Singapore

Purpose/Objective(s): Precision Stereotactic Body Radiotherapy (SBRT) delivers ablative doses to a target, while minimising the dose to surrounding critical organs. While the use of SBRT has been well established in early stage non-small cell lung cancer (NSCLC), concerns about toxicity and tolerability have limited its use or led to a reduction in prescribed dose in the elderly population, particularly when larger lesions are treated. We hypothesize that SBRT given to the elderly (defined as ≥65 yo and above) patient with a larger T2 and above lesion is safe and offers effective disease control in a population who is otherwise not fit for surgical resection.

Materials/Methods: To investigate this, we performed a retrospective review of treatment outcomes for patients ≥65 yo with biopsy proven and PET staged T2 N0 and T3 N0 NSCLC who received lung SBRT in our centre from 2009 to 2017. 1 patient who had no follow-up imaging was excluded. To account for different dose fractionations, all doses were converted into biological equivalent doses (BED) using an α/ßTumour = 10. Response to treatment was assessed on serial CT imaging performed ever 3-4 mo, using RECIST criteria and toxicities were prospectively recorded using CTCAEv4. Kaplan-Meier was performed and survival outcomes compared using log-rank test.

Results: We identified a total of 25 patients with a median age of 76.8yo (IQR: 72.2 – 79.9yo). 18 (72%) were deemed medically inoperable while 7(28%) declined surgery. Median GTV-ITV was 24.9cc (19.2 – 38.6cc) and median PTV was 64cc (50.5 – 83.6cc). Median D95 BED10 was 94.5 (94.1 – 132.3) with a median D10 BED10 of 113.81 (102.7 – 146.9). 4 patients relapsed in-field, representing a 2y and 3y target control of 88.2% and 80.9% respectively; 2 target failures developed distant failures at the same time. 2y and 3y control rates were 91.3% and 84.8% [same lobe], 83.3% and 70.9% [Nodal], 83.3% and 70.9% [Ipsilateral lung] and 80.1% and 65.8% [distant] respectively. 2y and 3y survival rates were 74.6% and 49.7% [overall, OS] and 86.3% and 67.8% [cancer specific, CSS]. In our cohort, a D95 BED10≥100Gy was not associated with improved target control or OS. SBRT in this population was well tolerated with 1(4%) patient reporting grade 3 pneumonitis. Despite significant chest wall doses [median V30: 52.8cc, 26.1 – 70.7cc], only one patient had a rib fracture. Another patient died 1 week following SBRT but this was attributed to a flare of his pneumonia and COPD post RT. Interestingly, poorer OS was observed in patients with significant interstitial scarring post SBRT (46mo [scarring] vs 68.8mo [no scarring]; p = 0.165).

Conclusion: Herein, our data demonstrates excellent outcomes in elderly patients with bulky T2 N0 and above NSCLC treated with SBRT.

Author Disclosure: I.H. Sin: None. B.S. Chia: None. C. Yip: None. W. Ng: None. T. Siow: None. A. Thiagarajan: None. K.L. Chua: Honoraria; Varian Medical Systems. Consultant; National Cancer Centre Singapore. Co-Chair Neuro Oncology Cancer Service Workgroup; National Cancer Centre Singapore.

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