Author of

• 11645

  +

  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

  • 11650

    +

    P2.08-005 - 4D-PET/CT-based adaptive dose escalated radiotherapy (RT) in locally advanced non-small cell lung cancer (LA-NSCLC) (ID 1171)

    09:30 - 09:30  |  Author(s): K. Clarke
    • Abstract

    Background
    There has been recent interest in dose escalation in LA-NSCLC, with the aim to improve both loco-regional control and overall survival. Attempts to dose escalate CT-defined volumes for radiotherapy (RT) for LA-NSCLC have been limited due to organ at risk (OAR) toxicity. We investigated the potential for adaptive dose-escalation to PET-defined volumes, using 4DPET/CT scans acquired prior to and during a course of radical chemo/RT (CRT).

    Methods
    This single institution study prospectively enrolled patients with NSCLC receiving CRT to a dose ≥60Gy, delivered in daily 2Gy treatments. 4DPET/CT scans were acquired prior to (week 0) and at weeks 2 and 4 during RT. RT was delivered using the intensity modulated RT (IMRT) plan developed from the week 0 scans. Three alternative dose escalated IMRT plans were developed offline based on the week 0, 2 and 4 scans. The PET avid primary (PET-T) and nodal disease (PET-N) volumes were auto-contoured using the 50%SUV~max~ metric. PET-T and PET-N were dose escalated to as high as possible while respecting OAR constraints and ensuring coverage of the clinical plan PTV. The D95% and D~max~ of the PET-T and PET-N were calculated and compared between week 0-2-4.

    Results
    Thirty-two patients were recruited, with 27 completing all scans. Sixteen patients were stage IIIA (60%), 9 were IIIB (33%) and 2 were IIA (7%). Eight patients (30%) had been prescribed a clinical dose of 60 Gy, 17 (63%) had 66 Gy, 1 patient 70Gy and 1 patient 74Gy. 25 patients (93%) were boosted successfully above the clinical plan doses at week 0; this reduced to 23 (85%) at week 2 and 20 (74%) at week 4. For all weeks combined, the D95 for PET-T was higher than that delivered to clinical PTV by a median of 16.2 Gy (4.2-37.4Gy). The D95 for PET-N exceeded that delivered to clinical PTV by 13.4Gy (6.8-29.7Gy). The median D95% to the PET-T at week 0, 2 and 4 were 74.4 Gy, 75.3Gy and 74.1Gy respectively. The median D~max~ to PET-T at week 0, 2 and 4 were 85.9Gy, 83.8Gy and 81.2Gy. The median D95% to PET-N at week 0, 2 and 4 was 74.3Gy, 71.0Gy and 69.5Gy. The median D~max~ to PET-N at week 0, 2 and 4 were 82.7Gy, 82.5Gy and 78.9Gy.

    Conclusion
    Using 4DPET/CT derived volumes, it is feasible to dose escalate a majority of patients, either at the onset or during RT. Though the PET-T was able to be escalated to higher doses than PET-N, nodal disease can still be boosted to significant doses. More patients were able to be dose escalated at the onset of RT; however mid-RT dose escalation allows the additional potential for adaptation.