Author of

• 20193

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  P3.14 - Radiotherapy (ID 730)

  • Event: WCLC 2017
  • Type: Poster Session with Presenters Present
  • Track: Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/18/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)

  • 24194

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    P3.14-004 - Pathological Study on the Clinical Target Volume (CTV) in Limited-Stage SCLC for CT-Simulation Based Thoracic Radiotherapy Planning (ID 9722)

    09:30 - 09:30  |  Author(s): W. Sun
    • Abstract

    Background:
    The microscopic extension, known as clinical target volume (CTV), of the primary tumor in locally advanced non-small cell lung cancer for chest radiotherapy planning has been well studied. However, the CTV of the primary tumor in limited-stage small cell lung cancer (SCLC) for thoracic radiotherapy planning has not been reported. In this study, we tried to quantify CTV of primary tumor in limited-stage SCLC with pathological approach.
    
    Method:
    Patients with stage T1-2N0-1M0 small cell lung cancer, treated with two cycles of etoposide plus cisplatin neoadjuvant chemotherapy or without neoadjuvant therapy were eligible for this study. Routine radical lobectomy and mediastinal lymph node dissection were performed for these patients. After operation, the intact lung lobe specimens were perfused with 10% neutral formalin and inflated as the natural state in the body. Specimens should be fixed for at least 12 hours. The fixed specimens were sectioned at 3mm thickness along the cross-sectional position of the body, and for each slice, the gross tumor and its surrounding 2cm lung tissue was embedded with paraffin and sliced with 4μm thickness. HE routine staining and CD56 immunohistochemical staining were applied. The slides were scanned by KFBIO reading software, and the pathologists confirmed the microscopic extension of the surrounding tumor. The minimal distances between microscopic nidus and the edge of gross tumor were measured.
    
    Result:
    Eight patients were enrolled, of whom 4 received 2 cycles of neoadjuvant chemotherapy and 4 received surgery without any neoadjuvant therapy. In patients who received neoadjuvant chemotherapy, one was diagnosed as squamous cell carcinoma after surgery and was excluded for further evaluation of CTV, while 1 patient achieved pathologically complete remission of tumor.The median range of CTV in patients received or did not receive neoadjuvant chemotherapy were 0.4mm (0.05mm-2.76mm) and 1.7mm (0.08mm-12.7mm) respectively, a margin of 1.4mm and 10.2mm could cover 95% of microscopic nidus (P=0.00).
    
    Conclusion:
    The preliminary results of this study indicated that to take into account 95% of the microscopic nidus, a 1.4mm and a 10.2mm margin should be need for CT-simulation based thoracic radiotherapy planning for limited-stage SCLC patients who were treated with or without induction chemotherapy. However, the sample size of this study was small and more cases are needed to justify the results.