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Reza Mehran



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    FP05 - Mesothelioma, Thymoma and Other Thoracic Malignancies (ID 135)

    • Event: WCLC 2020
    • Type: Posters (Featured)
    • Track: Mesothelioma, Thymoma and Other Thoracic Malignancies
    • Presentations: 1
    • Moderators:
    • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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      FP05.03 - Association between Baseline Tumor Thickness and Response to Neoadjuvant Chemotherapy in Malignant Pleural Mesothelioma (ID 3052)

      00:00 - 00:00  |  Author(s): Reza Mehran

      • Abstract
      • Presentation
      • Slides

      Introduction

      Tumor thickness in malignant pleural mesothelioma has been reported to be prognostic for survival and disease recurrence, but the relationship of tumor thickness and response to chemotherapy has not been explored. We sought to investigate the utility of baseline tumor thickness as a predictor of response to neoadjuvant chemotherapy (NAC).

      Methods

      Patients who underwent NAC followed by cytoreductive surgery were reviewed from 2000-2019. Chest CT performed before and after completion of NAC were measured for tumor thickness using the modified RECIST 1.1 criteria. Total tumor thickness consisted of three mediastinal and three chest wall mesurements. Radiologic response to NAC were categorized into partial response (PR≥30% decrease), progressive disease (PD, ≥20% increase) or stable disease (SD, -29% to +19% change) based on the change in total tumor thickness. Mean and median tumor thickness for each tumor response category was evaluated for total and percent change in tumor thickness after NAC. Overall survival (OS) was defined from time of diagnosis and compared between PD and PR. Multivariable logistic regression was performed for PD after neoadjuvant chemotherapy.

      Results

      143 patients were reviewed. Median age was 65 years, most patients were male (112, 78%), and white (123, 86%). Histology was comprised of 111(78%) epithelioid, 28(20%) biphasic, and 4(3%) sarcomatoid. All patients were pathologic stage I-III, NAC consisted of 108(76%) platinum/pemetrexed, 19(13%) dasatinib, and 16(11%) other. There were 36(25%) patients with PD, 54(38%) SD, and 53(37%) PR. Analysis for OS showed PR with improved survival compared to PD (27 vs. 13 months, p=0.007). There was a positive correlation between baseline tumors thickness and radiological response to NAC (r=0.537, p<0.001); this pattern was consistent for platinum/pemetrexed, dasatinib, and other therapies. The median baseline thickness for PD was 36 mm, which was thinner than SD (63mm, p<0.001) and PR (63mm, p<0.001). In tumors <36mm,10% of patients achieved PR, and 61% of patients achieved PD, compared to 45% PR (p<0.001) and 15% PD (p<0.001) in tumors above 36mm. Tumors <36mm was associated with PD (OR: 5.48; 95% CI: 1.82-17.26; p=0.003) in a multivariable model.

      Table. Multivariable Logistic Regression for Progressive Disease
      Variable Odds Ratio (95% Confidence interval) p-value
      Female sex 0.94 (0.25 - 3.06) 0.927
      Zubrod Performance Status 1.66 (0.71 - 3.90) 0.234
      Clinical N+ 0.74 (0.18 - 2.55) 0.652
      Epithelioid Histology 1.25 (0.39 - 4.46) 0.709
      Platinum/Pemetrexed 0.40 (0.13 - 1.29) 0.119
      Tumor<36mm 5.48 (1.82 - 17.26) 0.003
      Baseline SUVmax (Gray) 1.08 (0.98 - 1.17) 0.128

      Conclusion

      Responders to NAC portends longer survival. There seems to be a correlation between baseline tumor thickness and response to neoadjuvant chemotherapy. While these results will need further validation, it generates a hypothesis of differential tumor environment and response to neoadjuvant therapy in thinner and thicker tumors. Further studies should focus on defining the mesothelioma microenvironment based on radiographic tumor thickness.

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