A Prospective Randomized Study of the Radiotherapy Volume for Limited-stage Small Cell Lung Cancer: A Preliminary Report

Background and objective Controversies exists with regard to target volumes as far as thoracic radiotherapy (TRT) is concerned in the multimodality treatment for limited-stage small cell lung cancer (LSCLC). The aim of this study is to prospectively compare the local control rate, toxicity profiles, and overall survival (OS) between patients received different target volumes irradiation after induction chemotherapy. Methods LSCLC patients received 2 cycles of etoposide and cisplatin (EP) induction chemotherapy and were randomly assigned to receive TRT to either the post- or pre-chemotherapy tumor extent (GTV-T) as study arm and control arm, CTV-N included the positive nodal drainage area for both arms. One to 2 weeks after induction chemotherapy, 45 Gy/30 Fx/19 d TRT was administered concurrently with the third cycle of EP regimen. After that, additional 3 cycles of EP consolidation were administered. Prophylactic cranial irradiation (PCI) was administered to patients with a complete response. Results Thirty-seven and 40 patients were randomly assigned to study arm and control arm. The local recurrence rates were 32.4% and 28.2% respectively (P=0.80); the isolated nodal failure (INF) rate were 3.0% and 2.6% respectively (P=0.91); all INF sites were in the ipsilateral supraclavicular fossa. Medastinal N3 disease was the risk factor for INF (P=0.02, OR=14.13, 95%CI: 1.47-136.13). During radiotherapy, grade I, II weight loss was observed in 29.4%, 5.9% and 56.4%, 7.7% patients respectively (P=0.04). Grade 0-I and II-III late pulmonary injury was developed in 97.1%, 2.9% and 86.4%, 15.4% patients respectively (P=0.07). Median survival time was 22.1 months and 26.9 months respectively. The 1 to 3-year OS were 77.9%, 44.4%, 37.3% and 75.8%, 56.3%, 41.7% respectively (P=0.79). Conclusion The preliminary results of this study indicate that irradiant the post-chemotherapy tumor extent (GTV-T) and positive nodal drainage area did not decrease local control and overall survival while radiation toxicity was reduced. But the current sample size has not met designed requirements, and further investigation is warranted before final conclusions could be drawn.