Lung Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_34_3651 - Stereotactic Body Radiation Therapy (SBRT) for Patients with Stage I Non-Small Cell Lung Cancer Is Applicable to More Tumors than Sublobar Resection

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

Stereotactic Body Radiation Therapy (SBRT) for Patients with Stage I Non-Small Cell Lung Cancer Is Applicable to More Tumors than Sublobar Resection
A. J. Song1, J. Guo2, N. Evans3, S. Cowan3, T. Zhan4, and M. Werner-Wasik1; 1Dept of Radiation Oncology, Thomas Jefferson University Sidney Kimmel Cancer Center, Philadelphia, PA, 2Sidney Kimmel Medical College, Philadelphia, PA, 3Dept of Surgery, Thomas Jefferson University, Philadelphia, PA, 4Dept of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA

Purpose/Objective(s): Virtually all patients (pts) with medically inoperable Stage I non-small cell lung cancer (NSCLC) can receive Stereotactic Body Radiation Therapy (SBRT). However, the percentage of such pts in whom sublobar resection (SR) is technically feasible is not well known. This disparity can confound eligibility and clinical trial design when comparing SBRT vs. SR.

Materials/Methods: A retrospective review of pts treated with SBRT for lung lesions (3/2013-11/2017) was performed, identifying 137 pts. Of these, 37 pts were removed from analysis (33 received SBRT for lung metastases and 4 had no pre-SBRT imaging). For the remaining 100 pts, diagnostic CT chest and PET/CT images, SBRT dates and demographic data were collected. Two experienced board-certified thoracic surgeons reviewed independently each patient’s pre-SBRT diagnostic chest CT scans and filled out a custom survey. The survey asked questions on the technical feasibility of any SR (yes/no) and the reasons for the inability to perform wedge resection, WEDG (tumor size, depth, achievable margin status, location, other) or segmentectomy, SEG (tumor not confined to one segment, achievable margin status, size, location and clarity of segmental anatomy). Interrater agreement between the surgeons was measured using Cohen’s kappa coefficient by bootstrap methodology. Summary statistics were performed for baseline demographics, tumor characteristics, and reasons against resection.

Results: Of the 100 pts, 57% were female, with the median age of 75 years (range, 52-95) and median KPS of 80 (range, 40-100). Majority of pts (61%) had Stage IA1, T1a tumors, followed by Stage IA2, T1b (22%), and Stage IB, T2a (17%). For interrater agreement analysis, one pt each was removed from each set of surgeon responses due to inability to identify the tumor on images, leaving 98 pts analyzed. Comparing surgeon #1 vs. surgeon #2, 64 (65.3%) vs. 69 (70.3%) of tumors were amenable to SR, respectively (for an interrater agreement κ = 0.414). Of these pts, WEDG was feasible in 64 (100%) vs. 58 (84.1%) [κ = 0.473] and SEG was feasible in 42 (65.6%) vs. 43 (62.3%) (κ = 0.225), respectively. For surgeon #1, the most common reason against WEDG was “depth of tumor in lung” for 22 pts (64.7%) while against SEG it was “inadequate margin due to tumor location” and “segmental anatomy not clear on imaging”, both with 23 pts (41.1%). For surgeon #2, the most common reason against WEDG was also “depth of tumor in lung” for 32 pts (80%) and for SEG, “tumor not defined to one segment” in 44 pts (80%).

Conclusion: SBRT for pts with Stage I NSCLC is applicable to more tumors than SR, with approximately 30% of SBRT pts not able to undergo SR based on pretreatment diagnostic imaging. The interrater agreement was higher for WEDG than for SEG. This study illustrates that clinical trials comparing SBRT vs. SR are limited to a subpopulation of pts with Stage I NSCLC.

Author Disclosure: A.J. Song: None. J. Guo: None. N. Evans: None. T. Zhan: None. M. Werner-Wasik: Stock; Illumina.

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