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A. Bezjak



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    MO17 - Radiotherapy I: Stereotactic Ablative Body Radiotherapy (ID 106)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Radiation Oncology + Radiotherapy
    • Presentations: 1
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      MO17.03 - Incidental Prophylactic Nodal Irradiation and Patterns of Nodal Relapse in Inoperable Early Stage NSCLC Patients Treated with SBRT: A Case-Matched Analysis (ID 2024)

      16:25 - 16:30  |  Author(s): A. Bezjak

      • Abstract
      • Presentation
      • Slides

      Background
      Reported non-small cell lung cancer (NSCLC) nodal failure rates following stereotactic body radiotherapy (SBRT) are lower than those reported in the surgical series when matched for stage. We hypothesize that this effect is due to incidental prophylactic nodal irradiation.

      Methods
      A prospectively collected group of medically inoperable early stage NSCLC patients (n=179) from 2004 to 2010 was used to identify a patient cohort with nodal relapses (n=19). These cases were matched, 1:2, to controls, controlling for tumour volume (i.e. same or greater) and tumour location (i.e. same lobe). Reference (normalized total) point doses at the ipsilateral hilum and carina, demographic data, and clinical outcomes were extracted from the medical record. Multivariate logistical regression analyses determined variables of interest.

      Results
      The case and control cohorts were well matched with respect to age, sex, method of nodal staging, SUVmax, histology subtype, dose and length of follow up.. The controls, as expected, had larger gross tumour volumes (p=0.02). The mean hilar doses were 9.6 and 22.4 Gy for cases and controls, respectively (p=0.014). Similarly, the mean carinal doses were 7.0 and 9.2 Gy, respectively (p=0.13). The mean ipsilateral hilar doses were 19.8 and 3.6 Gy for ipsilateral non-hilar and hilar nodal relapses, respectively (p=0.01). The conditional density plot appears to demonstrate an inverse dose-effect relationship between ipsilateral hilar normalized total dose and risk of ipsilateral hilar relapse (Figure 1).Figure 1

      Conclusion
      Incidental hilar dose greater than 20 Gy (normalized to 2Gy/fraction) appears to be correlated with lack of hilar relapses in inoperable early stage NSCLC patients treated with SBRT.

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

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Radiation Oncology + Radiotherapy
    • Presentations: 2
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      P2.08-004 - Impact of medical co-morbidities on survival in patients treated with stereotactic body radiotherapy for early stage non-small cell lung cancer (ID 827)

      09:30 - 09:30  |  Author(s): A. Bezjak

      • Abstract

      Background
      Stereotactic body radiotherapy (SBRT) is an effective treatment for early stage inoperable non-small cell lung cancer (NSCLC), with loco-regional control of 80-90%. However, the median overall survival of these patients is limited. We evaluate the impact of co-morbidities on patient survival and whether a subset of patients who may not benefit from SBRT can be identified.

      Methods
      Patients treated on a prospective protocol at a single cancer center with SBRT for T1-T2N0 NSCLC from Oct 2004-May 2012 were evaluated. The most common doses delivered were 48Gy/4fr and 54Gy/3fr. The presence of significant medical co-morbidities including cardiac disease, COPD, cerebro-vascular disease, diabetes, previous pneumonectomy and oxygen dependence were recorded at baseline. Patient, tumor, and treatment data as well as outcomes were prospectively collected. Log rank tests were performed for survival analysis and chi squared tests used to analyze deaths within 1 year from radiotherapy treatment (D<1y). Cancer specific deaths (CSD) were defined as any death following a recurrence of the previously treated NSCLC.

      Results
      There were 279 patients identified, 134 female (48%) and 145 male (52%). The median age was 76 years (range 48-93). The performance status was ECOG 0 in 87 patients (31%), ECOG 1 in 127 patients (46%), ECOG 2 in 53 patients (19%) and ECOG 3 in 9 patients (3%). There were 212 (76%) with T1 tumors, the remainder (24%) T2 tumors. The median follow up was 1.3 years. At last follow up, 111 patients (40%) had died, including 42 (15%) patients with D<1y. Of all deaths, 25 (22.5%) were CSD, the remainder from other causes. There were 222 patients (80%) identified as having a significant co-morbidity, collectively these conditions did not influence deaths from any cause (DAC) or CSD. The presence of cardiac disease (N=67) led to an increased risk of DAC (HR 4.1, p = 0.04) but not CSD (HR 1.2, p=0.28). These results were more pronounced for D<1y, patients with cardiac disease having increased D<1y, (HR 7.34, p=0.007), but not CSD<1y, (HR 2.9, p=0.09). Other co-morbidities were not correlated of survival. ECOG status was correlated with both DAC (HR 15.1, p=0.005) and CSD (HR 9.3, p=0.05).

      Conclusion
      The presence of respiratory and vascular co-morbidities should not necessarily preclude a patient from receiving SBRT. ECOG status and prognosis from a cardiac point of view may be associated with poorer overall survival at 1 year and should be considered when assessing a patient’s suitability for SBRT.

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      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): A. Bezjak

      • 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.