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Pinjun Gu



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    JCSE01 - Joint IASLC-CSCO-CAALC Session (ID 63)

    • Event: WCLC 2019
    • Type: Joint IASLC-CSCO-CAALC Session
    • Track:
    • Presentations: 1
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      JCSE01.17 - Modelling the Immunosuppressive Difference of SBRT and CRT by Simulating the Dose to Circulating Lymphocytes in Non-Small Cell Lung Cancer (ID 3431)

      07:00 - 11:15  |  Author(s): Pinjun Gu

      • Abstract
      • Slides

      Abstract
      Background
      Radiation-dose delivered to circulating lymphocyte (CL) has detrimental effect on immune system for cancer patients. Our study established a model to compare the cumulative dose on CL of patients with conventional fractionation radiotherapy (CRT) and stereotactic body radiation therapy (SBRT) in lung cancer with different target volume.

      Methods
      The improved model is based on convolution algorithm suggested by Yovino(Cancer Investigation, 2013). The current blood DVHs of each organ were multiplied with treatment field DVH to generate original DVHs. During one second, 0.6% of whole-body blood circulates through each organ and rest body according to blood circulating pattern and then new DVHs of organ were generated. The new DVHs would be used for next second’s calculation with treatment field DVH. Conventional fractionated non-small cell lung cancer plan 60Gy (30 fractions*2.0Gy) and SBRT plan 50Gy (5fractions*10Gy) are constructed for three patients with different target volumes. The primary endpoint is peak cumulative blood dose (PCBC).

      Results
      PCBC of three patients with CRT and SBRT were calculated as Figure 1. PCBC with CRT to circulating lymphocyte (CL) were 2.5Gy, 5.6Gy, 9.5Gy in PTV-volume 17cm3, 33cm3, 120cm3, respectively. And PCBC with SBRT to circulating lymphocyte (CL) were 2.1Gy, 2.9Gy, 6.0Gy in PTV-volume 17cm3, 33cm3, 120cm3, respectively. PCBC gap of SBRT to circulating lymphocyte (CL) was decreased 0.4Gy, 2.7Gy, 3.5Gy in PTV-volume 17cm3, 33cm3, 120cm3, respectively.



      Conclusion
      An improved simulation-model was established, SBRT, compared to CRT, will lead to decreased cumulative dose on CL, which may cause less impact on immune system with the enlargement of PTV-volume.

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    P1.04 - Immuno-oncology (ID 164)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Immuno-oncology
    • Presentations: 1
    • Now Available
    • Moderators:
    • Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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      P1.04-69 - Modelling the Immunosuppressive Difference of SBRT and CRT by Simulating the Dose to Circulating Lymphocytes in Non-Small Cell Lung Cancer (Now Available) (ID 295)

      09:45 - 18:00  |  Author(s): Pinjun Gu

      • Abstract
      • Slides

      Background

      Radiation-dose delivered to circulating lymphocyte (CL) has detrimental effect on immune system for cancer patients. Our study established a model to compare the cumulative dose on CL of patients with conventional fractionation radiotherapy (CRT) and stereotactic body radiation therapy (SBRT) in lung cancer with different target volume.

      Method

      The improved model is based on convolution algorithm suggested by Yovino(Cancer Investigation, 2013). The current blood DVHs of each organ were multiplied with treatment field DVH to generate original DVHs. During one second, 0.6% of whole-body blood circulates through each organ and rest body according to blood circulating pattern and then new DVHs of organ were generated. The new DVHs would be used for next second’s calculation with treatment field DVH. Conventional fractionated non-small cell lung cancer plan 60Gy (30 fractions*2.0Gy) and SBRT plan 50Gy (5fractions*10Gy) are constructed for three patients with different target volumes. The primary endpoint is peak cumulative blood dose (PCBC).

      Result

      PCBC of three patients with CRT and SBRT were calculated as Figure 1. PCBC with CRT to circulating lymphocyte (CL) were 2.5Gy, 5.6Gy, 9.5Gy in PTV-volume 17cm3, 33cm3, 120cm3, respectively. And PCBC with SBRT to circulating lymphocyte (CL) were 2.1Gy, 2.9Gy, 6.0Gy in PTV-volume 17cm3, 33cm3, 120cm3, respectively. PCBC gap of SBRT to circulating lymphocyte (CL) was decreased 0.4Gy, 2.7Gy, 3.5Gy in PTV-volume 17cm3, 33cm3, 120cm3, respectively.

      figure 1.jpg

      Conclusion

      An improved simulation-model was established, SBRT, compared to CRT, will lead to decreased cumulative dose on CL, which may cause less impact on immune system with the enlargement of PTV-volume.

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    P1.18 - Treatment of Locoregional Disease - NSCLC (ID 190)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Treatment of Locoregional Disease - NSCLC
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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      P1.18-15 - Dosimetric and Toxicity Benefits of Adaptive IMRT in Patients with Stage III Non-Small Cell Lung Cancer (ID 396)

      09:45 - 18:00  |  Author(s): Pinjun Gu

      • Abstract
      • Slides

      Background

      Multiple studies observed anatomical changes or tumor shrinkage during concurrent chemoradiotherapy in patients with non-small cell lung cancer (NSCLC). Mid-treatment CT based adaptive radiotherapy targeting to the shrunken tumor can reduce the dose to adjacent normal tissue or potentially deliver a higher dose to the tumor. We aimed to quantitatively analyze the benefit of intensity-modulated radiotherapy (IMRT) adapting to CT changes at the 20th fraction in stage III NSCLC patients.

      Method

      We retrospectively evaluated consecutive patients with unresectable stage III NSCLC treated with adaptive IMRT from November 2017 to August 2018. The eligibility criteria included a mid-treatment CT simulation for replanning at the 20th fraction and a follow-up of at least 6 months. The prescribed dose was 64-66 Gy in 30 fractions unless exceeding the dose limit. Normal tissues were delineated according to RTOG1106 atlas on organs at risk under the supervision of a senior physician. Dose-volume histograms were calculated for the initial plans, composite adaptive plans, and lung isotoxic boost plans. Radiation pneumonitis (RP) and esophagitis (RE) were graded per CTCAE v4.03. Univariate logistic regression was applied to analyze the correlation between dosimetric factors and adverse events.

      Result

      53 patients were eligible in this study. The average GTV shrinkage was -40.9% at the 20th fraction. Comparing the dosimetric factors of the composite adaptive plans to the initial ones, the GTV coverage was found marginally higher (P=0.002). The doses to normal tissues were significantly lower (all Ps<0.001) in heart mean dose by 109.5 cGy, esophagus V60 by 1.53%, cord maximum dose by -272.7 cGy, lung V20 and mean lung dose (MLD) by 1.11% and 79.2 cGy, respectively. The tumor targets could potentially get an average lung isotoxic boost of 481 cGy. Eight patients (15.1%) had grade 2 RP while no grade 3 or higher RP occurred. Twenty-three patients (43.4%) developed grade ≥ 2 RE. MLD was significantly associated with grade 2 RP with an odds ratio of 1.39 per 100 cGy increase (95% CI, 1.01 to 1.91; P=0.042). Esophagus V60 was significantly associated with grade ≥ 2 RE with an odds ratio of 1.15 per 1% increase (95% CI, 1.04 to 1.28; P=0.009). (Table 1)

      Factors

      Initial Plans

      Adaptive Plans

      Mean difference

      95%CI

      P Value

      Targets

      PGTV (%)

      92.96

      93.81

      0.85

      0.33

      1.37

      0.002

      PTV(%)

      94.13

      94.54

      0.41

      0.35

      0.80

      0.033

      Lung

      V5(%)

      46.77

      45.72

      -1.05

      -0.70

      -1.41

      <0.001

      V20(%)

      25.15

      24.04

      -1.11

      -0.80

      -1.42

      <0.001

      V30(%)

      18.62

      17.60

      -1.02

      -0.77

      -1.27

      <0.001

      MLD (cGy)

      1411.4

      1332.2

      -79.2

      -60.1

      -98.4

      <0.001

      Heart

      V30(%)

      17.40

      15.11

      -2.29

      -0.94

      -3.62

      0.001

      V40(%)

      10.87

      9.06

      -1.81

      -0.98

      -2.64

      <0.001

      V55(%)

      4.06

      2.79

      -1.27

      -0.76

      -1.77

      <0.001

      Mean Dose(cGy)

      1504.5

      1395.0

      -109.5

      -67.88

      -151.22

      <0.001

      Pericardium

      V30(%)

      32.17

      30.43

      -1.74

      -0.77

      -2.70

      0.001

      V40(%)

      25.70

      24.00

      -1.7

      -0.76

      -2.64

      0.001

      V55(%)

      13.87

      11.87

      -2

      -1.34

      -2.66

      <0.001

      Mean Dose(cGy)

      2192.9

      2091.2

      -101.7

      -60.00

      -143.3

      <0.001

      Esophagus

      V40(%)

      39.43

      36.49

      -2.94

      -1.62

      -4.27

      <0.001

      V50(%)

      27.89

      24.08

      -3.81

      -2.36

      -5.27

      <0.001

      V60(%)

      7.57

      6.04

      -1.53

      -0.96

      -2.09

      <0.001

      Max Dose(cGy)

      6498.3

      6336.7

      -161.6

      -101.99

      -221.3

      <0.001

      Cord

      Max Dose(cGy)

      4113.0

      3840.3

      -272.7

      -209.51

      -335.93

      <0.001

      Conclusion

      By adapting to the changes on CT scans at the 20th fraction, the adaptive IMRT approach provides significant dosimetric benefits and has the potential to lower the risk of symptomatic pneumonitis and esophagitis in stage III NSCLC.

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