Author of

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  P2.08 - Poster Session 2 - Radiotherapy (ID 198)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11654

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    P2.08-009 - Stereotactic Ablative Body Radiotherapy (SABR) Outcomes for Primary and Metastatic Non-Small Cell Lung Cancer (NSCLC) Pulmonary Tumours (ID 1091)

    09:30 - 09:30  |  Author(s): A. Kim
    • Abstract

    Background
    To evaluate the clinical outcomes following SABR to early-stage NSCLC and pulmonary metastases (Mets) from NSCLC, including potential predictive factors and a focus on chest wall (CW) toxicities.

    Methods
    From our prospective lung SBRT database, we identified 240 NSCLC lung tumors in 209 patients treated with SABR between 2008 and 2011. 228 were primary NSCLC and 12 were NSCLC Mets. The institutional policy was to deliver 48-52 Gy in 4 fractions (fx) for peripheral tumors and 50 Gy in 5 fx for central tumors. Local control (LC) was defined as the absence of recurrence within or ≤1 cm beyond the planning target volume (PTV). Lobar LC was defined as absence of recurrence within the same lobe. All tumors were categorized as adjacent to the CW (PTV touching the CW) or not, to determine if this localisation can predict for rib fracture. Age, comorbidities, lobe of the target lesion, stage, tumor size, maximal tumor standardized uptake value (SUV), total dose and various dose-volume histogram metrics were also evaluated for their predictive significance.

    Results
    The median follow-up was 20.8 and 18.1 months (range, 0.2–52.1 and 15.3–46.2) for primary NSCLC and Mets, respectively. 168/240 tumors (70%) were biopsy-proven NSCLC. Of the 228 primary NSCLC, the majority were stage I (192/228; T1a=136, T1b=21, T2a=35). Among all primary tumors, the 2-year LC was 94.8%. LC did not differ between biopsy-proven or presumed tumor, and did not differ between primary NSCLC and NSCLC Mets. For the whole cohort, only the presence of a respiratory comorbidity predicted for better local control (p=0.021) on multivariate analysis. In stage I NSCLC, the 2-year LC, lobar LC, regional control, distant control (DC) and overall survival (OS) were 95.5%, 91.3%, 89.3%, 74.7% and 77.9%, respectively. The 2-year OS rates for non-stage I primary NSCLC and Mets from lung were 69.2% and 48.6%, respectively. The 2-year DC rates in all primary NSCLC and NSCLC Mets were 73.6% and 20.8%, respectively. Among primary NSCLC, upper lobe tumors predicted for a better DC compared to lower lobe tumors (p=0.009). Of the 240 lung tumors, 132 (55%) were adjacent to the CW and had a significant greater risk of rib fracture. The 2-year risk of fracture was 29.6% versus 8.1%, for tumors adjacent and not adjacent to the CW, respectively (p<0.001). The median time to fracture was 15.9 months. 51% of rib fractures were symptomatic. There was a suggestion that a higher conformity index (ratio of the 95% isodose volume to the PTV) predicted for a higher risk of rib fracture (p=0.067).

    Conclusion
    The excellent LC rate post-SABR seems similar in primary NSCLC and in NSCLC Mets, and having a respiratory comorbidity predicted favourably for LC. Patients with lower lobe tumors had higher risk of distant relapse. Patients with tumors adjacent to the CW are at significantly greater risk of rib fracture post-SABR and should be well informed prior to treatment.