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P. Souquet

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    MINI 33 - Radiotherapy and Complications (ID 164)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Treatment of Locoregional Disease – NSCLC
    • Presentations: 1
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      MINI33.06 - Prospective Monitoring of Lung Function Test with CO and NO Diffusion during Thoracic Radiotherapy: Preliminary Results of the CONORT Study (ID 2402)

      18:30 - 20:00  |  Author(s): P. Souquet

      • Abstract
      • Presentation
      • Slides

      Thoracic radiotherapy is a usual treatment for lung cancer; either at early-stages (stereotactic mode) or at locally advanced stages (conventional radiotherapy mode). Thoracic irradiation appears to have little impact on lung volume such as forced expiratory volume in one second (FEV1) or forced vital capacity (FCV). By contrast, carbon monoxide diffusing capacity (TLCO) may be altered under thoracic radiotherapy. Pulmonary diffusion may be also evaluated by the NO (azote monoxide) diffusion capacity (TLNO). Moreover, double assessment of NO and CO diffusing capacities open the way to understand if alteration of lung diffusion is due to alveolar membrane and/or a pulmonary capillary alteration. CONORT aims at measuring pulmonary function tests (PFTs), in particular the CO and NO diffusing capacity, during thoracic radiotherapy.

      Prospective multicenter study. CONORT study was approved by the Lyon Sud-Est IV ethics committee and the database was declared to the national information registry authority as required by French laws. Overall 112 patients must be included to estimate a difference of 15% in diffusing capacity test, with a 90% power and a 5% alpha risk. All consecutive patients treated by thoracic radiotherapy in Lyon Sud Hospital were included regardless of histology and radiotherapy technique. PFTs including double diffusion are performed by the same operator and using the same technic, before-, during-, at the end-, six weeks after- and six months after- thoracic irradiation. All included patients gave their consent. Results at PFTs were expressed in % of theoretical value (%th), and were compared using Student t test.

      Between 1[st] February 2014 and 14 April 2015, 88 patients were included and 62 have been analyzed. Patients were male in 73%, mean age was 67.4 years. Radiotherapy technique was intensity-modulated radiation therapy (IMRT) in 61%, stereotactic radiotherapy (SBRT) in 32%, and 3D conformal radiotherapy in 7%. Mean pretreatment FEV1 was 2.06L (78.9% of the standard), mean FCV was 3.17L (94.9%), mean TLCO was 16.5 (64.7%) and mean TLNO was 72.7 (60.3%). FEV1 and FCV were stable during and after radiotherapy. However, mean TLCO decreased by 4.4% (P=0.01) between first and fourth PFT, mean DLNO decreased by 4% (P=0.001) between first and second PFT, mean VC (capillary lung volume) decreased by 6.24% between first and fourth PFT (P=0.011), and DM (membrane diffusing capacity) decreased by 3.6% between first and second PFT (P=0.001).

      CONORT is the first study evaluating the potential impact of thoracic radiotherapy on double measurement of lung diffusing capacity. These preliminary results showed that thoracic radiotherapy has little impact on lung volumes. However, lung diffusion decreases, initially by membrane alteration and then by capillary alteration. Results at 6 months showed that this alteration is fully recovered. Updated data will be presented at meeting.

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