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C. Deroose



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    MO23 - Radiotherapy II: Lung Toxicity, Target Definition and Quality Assurance (ID 107)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Radiation Oncology + Radiotherapy
    • Presentations: 1
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      MO23.10 - Addition of EBUS-mapping of the mediastinum to PET/CT based selective nodal irradiation in NSCLC decreases geographical miss and nodal GTV volume (ID 2841)

      11:25 - 11:30  |  Author(s): C. Deroose

      • Abstract
      • Presentation
      • Slides

      Background
      FDG-PET/CT based selective lymph node (LN) irradiation is the standard when using 3D-conformal techniques (3D-CRT) for locally advanced NSCLC. With 3D-CRT, adjacent LN not included in the target volume still receive a substantial radiation dose. With current new techniques (IMRT/VMAT), the radiation dose to non-involved LN decreases, which raises the question whether selective nodal irradiation based on PET/CT is still safe. We therefore evaluated the impact of adding EBUS-TBNA (endobronchial ultrasound guided transbronchial needle aspiration)-mapping of the mediastinal LN to PET/CT in avoiding geographical miss, and on the size of nodal GTV (gross tumor volume).

      Methods
      Consecutive NSCLC-patients referred for radiotherapy (RT) in 2012 who underwent EBUS-TBNA were included. False negative (FN) LN for different constellations of PET, CT and EBUS-TBNA based on literature data were calculated, to evaluate the safety of excluding LNs based on CT, PET and EBUS findings. A practical algorithm when to include LN in the GTV was made, and tested on our patients. Results are expressed as mean +/- SD and range.

      Results
      Twenty-five consecutive patients with a full EBUS-TBNA mapping before RT were included: 11 women, 14 men; 17 adenocarcinoma, 8 squamous cell carcinoma; 14 right-sided and 11 left-sided tumors. Mean age: 62.5 +/- 9.7 years. All patients had stage III-disease based on PET-CT. LN stations 1,2R,2L,3,4R,4L,5,6,7,8,9,10-11L,10-11R were analyzed on CT- and PET-scan (=325 LN). Sixty-seven were enlarged (≥10mm), of which 63 were PET-positive. Twelve normal-sized LNs were PET-positive. Fifty LNs were investigated with EBUS-TBNA (mean: 2/patient +/-0.96;1-5): 28 were malignant, 22 normal. EBUS-TBNA detected 1 cancer-containing normal-sized LN without FDG-uptake, thus 1/25 geographical miss (4%). The cancer prevalence, taking into account the FN rate of EBUS of 20%, was calculated (Fig.1). With addition of EBUS, in PET-negative patients FN decreases with 10% for enlarged LN, and with 5% for normal-sized LN. An algorithm when to include a LN in the GTV is proposed (Fig.1). According to this algorithm, in our population 3/79 (4%) enlarged or PET-positive LN would be excluded from the GTV. At patient level, this was a GTV decrease in 3 (12%) patients.

      Conclusion
      When incidental nodal irradiation is low such as in IMRT or VMAT, EBUS-TBNA should be added to FDG-PET/CT for mediastinal staging. This avoids geographical miss in 4% of patients, and decreases the radiation volume in 12% of patients. A practical algorithm is proposed.

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    P3.09 - Poster Session 3 - Combined Modality (ID 214)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Combined Modality
    • Presentations: 1
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      P3.09-004 - Oligometastatic non-small cell lung cancer: a simulation expert multidisciplinary tumor board. (ID 1122)

      09:30 - 09:30  |  Author(s): C. Deroose

      • Abstract

      Background
      Series on aggressive local treatment in selected patients with oligometastatic non-small cell lung cancer (NSCLC) are mostly retrospective, and prospective data are scarce (De Ruysscher et al, JTO 7:1547-1555, 2012). Although a precise definition is lacking, ‘oligometastatic NSCLC’ is considered an intermediate biologic state of restricted metastatic capacity with a limited number of metastases. The turning point between oligometastatic and polymetastatic is merely based on personal opinion and situated somewhere between 1 and 5 distant metastases. In the absence of clear definitions or clinical practice recommendations, a treatment decision is mainly driven by the opinion of each local multidisciplinary tumor board (MDTB).

      Methods
      As the consideration of and the treatment modality for oligometastatic NSCLC is a controversial area in respiratory oncology, in preparation of a recent dedicated workshop, we simulated a MDTB with international experts in the field. Multiple disciplines from 7 different centers participated in the MDTB, including pathology (1), nuclear medicine physician (1), thoracic surgery (3), radiation oncology (3), and respiratory oncology (3). Participants were asked to assess an electronic file describing 10 clinical ‘oligometastatic NSCLC’ cases, with 2 simple questions per case: 1. Do you consider this case ‘oligometastatic’ (Yes/No) and 2. What is your preferred treatment proposal.

      Results
      A full response was returned by all 11 specialists taking part in the simulated MDTB. Only 1 case was considered ‘oligometastatic NSCLC’ by all MDTB members. The presented cases were considered by a median of 78% (range 36-100%) of responders as true oligometastatic disease. Despite the fact that each responder gave only one treatment proposal, a median of 4 different treatment proposals (range 2-6) was made per case. Except for brain metastases, most team members would treat the locoregional thoracic disease before the distant metastases. No preference towards neo-adjuvant or adjuvant chemotherapy could be found. The option for surgery or radiation therapy as part of a combined modality treatment was mainly driven by the physicians’ preference.

      Conclusion
      Our simulated MDTB shows that oligometastatic NSCLC is an entity with many unanswered questions, and thus a major challenge for clinicians. Patients with oligometastatic NSCLC are in the need of 1. discussion at an experienced multidisciplinary tumor board to select patients for a radical combined modality approach; 2. multidisciplinary prospective research protocols to set better definitions of oligometastic NSCLC, evaluate the validity of a radical approach, and to optimize therapeutic modalities.