Purpose: The local control of inoperable non-small cell lung cancer (NSCLC) using standard radiotherapy (RT) doses is inadequate. Dose escalation is a potential strategy to improve the local control for patients with NSCLC; however, the optimal dose required for local control in this setting is unknown.
Methods and materials: Patients with unresectable or inoperable stage II/III NSCLC with ECOG≤1 received 48 Gy in 20 daily fractions using intensity-modulated radiotherapy, followed by 1 of 3 boost dose levels: 16.8 Gy/7 (cumulative 2 Gy equivalent dose [EQD2]≅76 Gy/38), 20.0 Gy/7 (EQD2≅84 Gy/42), and 22.7 Gy/7 (EQD2≅92 Gy/46). Two cycles of cisplatin/etoposide chemotherapy were given concurrent with RT. The maximum tolerated dose was defined as the dose at which ≥30% experienced dose-limiting toxicity (any NCIC Common Terminology for Adverse Events V3.0 grade 3 or higher acute toxicity).
Results: Twelve patients completed treatment with a median follow-up of 22 months (range, 7 to 48). The median age was 72 (range, 54 to 80) and 50% of patients had adenocarcinoma. Five, 3, and 4 patients were treated on dose levels 1, 2, and 3, respectively. No dose-limiting toxicity was observed. One-year local progression-free survival and overall survival estimates were 81% and 58%, respectively.
Conclusions: Hypofractionated intensity-modulated radiotherapy was well tolerated and provided meaningful local control for patients with locally advanced inoperable NSCLC. The maximum tolerated dose of RT in this setting lies beyond an EQD2 of 92 Gy/46 and further dose escalation in this setting is warranted.