Involved-field radiotherapy for patients with limited small cell lung cancer: Patterns of local-regional failure and feasibility

Abstract

7554 Background: To investigate the feasibility of the involved-field radiotherapy in patients with limited-stage small cell lung cancer (LSCLC) according to the patterns of local failure, focused on the first local-regional failure. Methods: Two clinical phase II studies for patients with LSCLC treated at our institute between 1997 and 2007 were reviewed. All patients received combined chemotherapy (CHT) with cisplatin and etoposide, and thoracic RT (TRT) was generally delivered sequentially following one to three cycles of CHT and consisted of either 56 Gy in 40 fractions for 4 weeks or 55 Gy in 22 fractions for 4–5 weeks. TRT fields encompassed primary tumor volume (post-CHT) and the involved nodal areas (pre- and post-CHT) without elective node irradiation. The local-regional failure was defined as failure within thoracic cavity and supraclavicular fossa except for pleural effusion, which was then divided into two subtypes: in-field and out-field failure according to the first occurred site in the planning target volume or not. Results: There were 89 patients completed the planed regimen and eligible for evaluating patterns of failure, 54 patients (57%) in 56 Gy cohort and 35 patients(43%) in 55 Gy cohort. The media cycles of CHT were 6 (4–8). The overall survival and local progression-free survival rates for 89 patients at 2 years were 56% and 71%, respectively, with a median survival of 25.6 months. 56 patients (63%) developed distant metastases and 21 patients (24%) developed local-regional failures: 12 in-field and 9 out-field. 8 out of 9 out-field failures occurred in the ipsilateral supraclavicular fossa, and the media duration to the end of TRT was 6 mouths (5–14). Comparing the 56 Gy and 55 Gy cohorts, the rates of any thoracic, in-field and out-field failures were no difference significantly. Conclusions: Thoracic radiotherapy using involved-field technique in patients with LSCLC resulted in a high failure rate of the supraclavicular fossa. Whether improving accuracy for the initial evaluation of clinical stage could reduce out-field failure in supraclavicular fossa need to be investigated. No significant financial relationships to disclose.