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H. Wu



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    P2.09 - Poster Session 2 - Combined Modality (ID 213)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Combined Modality
    • Presentations: 1
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      P2.09-015 - Role of postoperative radiotherapy after curative resection and adjuvant chemotherapy for patients with pathological stage N2 non-small cell lung cancer: A propensity score matching analysis (ID 2953)

      09:30 - 09:30  |  Author(s): H. Wu

      • Abstract

      Background
      To evaluate the role of postoperative radiotherapy (PORT) after curative resection and adjuvant chemotherapy for patients with pathological stage N2 non-small cell lung cancer (NSCLC).

      Methods
      We performed a retrospective review of 219 consecutive patients who underwent curative surgery followed by adjuvant chemotherapy between 2000 and 2011. Among 219 patients, 41 received PORT additionally. Propensity scores for PORT receipt were calculated for each patient and used for matching to patients without PORT. 118 patients in non-PORT group and 39 patients in PORT group were matched. Clinical and pathologic characteristics were well-balanced after matching. PORT was delivered using conventional technique (n=13) or three-dimensional conformal technique (n=26) with median dose of 54 Gy (range, 50-60). The median follow-up duration for matched patients was 47 months.

      Results
      During the follow-up, 58 patients (49.2%) experienced loco-regional failure in the non-PORT group and 12 patients (30.8%) in the PORT group. Distant metastasis occurred in 68 patients (57.6%) in non-PORT group and 22 patients (56.4%) in PORT group. PORT was associated with improved loco-regional control rate (LRC) (5yr LRC 67.0% vs. 48.4%, p = 0.047), but not disease-free survival (DFS) (5yr DFS 43.3% vs. 32.3%, p = 0.257). An exploratory subgroup analysis suggested a potential DFS benefit of PORT in patients with multiple stations of mediastinal lymph node metastasis (5yr DFS 42.8% vs. 16.6%, p = 0.023). Grade 3 radiation pneumonitis and esophagitis was seen in only one patient, respectively.

      Conclusion
      In pathological stage N2 NSCLC patients, more than half eventually developed distant metastasis despite adjuvant chemotherapy. PORT increased LRC in these propensity-matched patients, but did not DFS. However, patients with multiple stations of mediastinal lymph node metastasis appear to benefit from PORT.

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    P3.05 - Poster Session 3 - Preclinical Models of Therapeutics/Imaging (ID 159)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.05-018 - Does elongation of treatment time in respiratory gated radiotherapy alter cell survivals? (ID 3023)

      09:30 - 09:30  |  Author(s): H. Wu

      • Abstract

      Background
      Respiratory gated radiotherapy (RGRT) is a modern radiotherapy technique, which is increasingly used technique to take account of respiratory motion. One potential risk of RGRT is the possibility of sublethal repair during treatment leading more tumor cell survival. This study assessd the influence of elongation of treatment time in respiratory gated radiotherapy by measuring cell survival in vitro.

      Methods
      Human lung cancer cell lines, H460 and H1299, were irradiated with 6MV photons using Varian 21EX linear accelerator in two different delivery models. Cells of conventional model irradiated continuously while the other cells irradiated with gated delivery. Doses of 2 Gy, 4 Gy and 8 Gy were studied. In conventional model, treatment times were 0.5 min for 2 Gy and 3min for 8 Gy including latency for multiple field. In gated delivery model, treatment times were 2.5 min for 2 Gy and 11 min for 8 Gy with 20% gating efficacy.

      Results
      H1299 cells were radioresistant than H460 cells (P<0.001). Elongation of treatment time caused significant increase in survival fraction in H1299 cell line (p=0.046). In H460 cell line survival fractions also increased but differences were not statistically significant (p=0.107). Relative differences between two delivery models in log scale survival fraction were not increased in higher dose.

      Conclusion
      The biologic effects of protracted delivery with gated technique were different between cell lines, suggesting influence of diversity of sublethal damage repair. More radioresistant cell lines were affected by elongation of treatment time. These results suggest that potential risk of sparing tumor in prolonged delivery time with gated radiotherapy should be considered in resistant tumor at the clinic.