Author of

• 10692

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  P1.08 - Poster Session 1 - Radiotherapy (ID 195)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 10708

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    P1.08-016 - Does lung stereotactic body radiation therapy affect lung membrane diffusion? (ID 1893)

    09:30 - 09:30  |  Author(s): S. Mehiri
    • Abstract

    Background
    Stereotactic body radiation therapy (SBRT) is becoming a standard of care in medically inoperable early stage non-small cell lung cancer (NSCLC), and is increasingly used in some solitary lung metastases. Lung toxicity remains however the main concern of this technique. This study aims to evaluate pulmonary function and lung membrane diffusion modifications after lung SBRT.

    Methods
    Retrospective analysis of pulmonary function tests (PFTs) in 40 patients undergoing SBRT for NSCLC (N=30) or lung solitary metastases (N=10), between 2009 and 2010. SBRT doses ranged between 48-60 Gy in 5-13 fractions. Normal lung volume receiving ≥ 30 Gy (V30), ≥ 20 Gy (V20), ≥ 5 Gy (V5) and mean lung dose (MLD) were calculated. Forced Expiratory Volume in 1 Second (FEV1), the ratio FEV 1 and Forced Vital Capacity (FEV1/FVC), and diffusing capacity of the lung for carbon monoxide (DLCO) were measured 1 month before SBRT, 6 weeks, then 4 and 6 months after SBRT. Respiratory symptoms were assessed according to CTCAE v4.0. Pre-and post-treatment values were compared using t Student test

    Results
    Median follow-up was 7 months (3-32 months), and median age was 70.6 years (51-86 years). Grade II-III chronic obstructive pulmonary disease was observed in 7 patients. Mean tumours diameter was 19.2 mm (7-53 mm), and 72% of lesions were peripheral. Mean planned target volume (PTV) and normal lung volume were 44 cc (3-162 cc), and 36149 cc (993-5146 cc) respectively. The mean values of MLD, V30, V20, and V5 were 4.7 Gy, 3.5%, 6.5%, 17.8% respectively. The mean decrease was 6.8% for FEV1, and 11.3% for FEV1/FVC. Mean DLCO remained unchanged with values of 48% predicted, and no significant respiratory symptoms were observed. The complete response rate was 90%, and 2 years progression free survival and overall survival were 72 and 76% respectively.

    Conclusion
    SBRT did not impair DLCO, and the changes of forced expiratory volumes were not significant, without significant clinical repercussion, even in COPD patients. These data are similar to those observed in several studies, and confirm the safety of the dose fractionation delivered to the current patients. Further studies are needed to evaluate the impact of SBRT on membrane diffusion. We are presently evaluating, the diffusing capacity for nitric oxide, a potentially more sensitive surrogate that could unmask subtle diffusion troubles and allow more accurate lung function monitoring.