Original Article
Local control rates with five fractions of stereotactic body radiotherapy for primary lung tumors: a single institution experience of 153 consecutive patients
Abstract
Background: We report our institutional experience with stereotactic body radiotherapy (SBRT) for treatment of non-small cell lung cancer (NSCLC).
Methods: One hundred and fifty-three consecutive patients diagnosed with NSCLC were treated with image-guided SBRT between 2008 and 2012. Stage I patients were treated in lieu of resection, stage II-III patients were not candidates for concurrent chemoradiation and had disease amenable to SBRT and stage IV patients had oligometastatic disease. The median prescribed isocenter dose was 50 Gy in five fractions (range, 40-60 Gy) with the majority (n=121) receiving 50 Gy in five fractions. The 80% isodose line covered the planning target volume (PTV) [defined as gross tumor volume (GTV) + 7-11 mm volumetric expansion). Follow-up ranged from 1-46 months with a median of 13 months.
Results: The 1- and 2-year local control (LC) rates for all patients were 92% and 85% respectively. For 111 patients with stage I NSCLC, 1- and 2-year LC was 95% and 85%, with all local recurrence (LR) occurring within 2 years. LC at 1- and 2-year was 87% for both stage II (n=19) and stage III (n=14), with all LR occurring within 10 months. For oligometastatic stage IV (n=9) patients, LC at 1- and 2-year was 71%, with all LR occurring within 5 months. Two-year LC among patients with tumors <1 cm was 100% compared to 84% for those with tumor size >1 cm. Tumor histology, prescribed dose, patient age, and prior radiotherapy (RT) or surgery had no significant impact on LC rates. Prior chemotherapy had a significant negative impact on LC with 1- and 2-year LC of 59%, compared to 1- and 2-year LC of 93% and 85%, respectively (P=0.015). n multivariate analysis, stage was the only significant predictor of LC. Among stage I NSCLC patients, 6 of 111 developed LR, 13 developed distant failures (of whom 5 also developed LR). Of these 111 patients, 5 died from NSCLC and 2 died from causes other than NSCLC; no patient died from treatment-related toxicity.
Conclusions: SBRT plays a vital role and offers excellent LC in medically-inoperable NSCLC patients, with treatment during the early stage of the disease determined as the single most significant predictor of LC on multivariate analysis.
Methods: One hundred and fifty-three consecutive patients diagnosed with NSCLC were treated with image-guided SBRT between 2008 and 2012. Stage I patients were treated in lieu of resection, stage II-III patients were not candidates for concurrent chemoradiation and had disease amenable to SBRT and stage IV patients had oligometastatic disease. The median prescribed isocenter dose was 50 Gy in five fractions (range, 40-60 Gy) with the majority (n=121) receiving 50 Gy in five fractions. The 80% isodose line covered the planning target volume (PTV) [defined as gross tumor volume (GTV) + 7-11 mm volumetric expansion). Follow-up ranged from 1-46 months with a median of 13 months.
Results: The 1- and 2-year local control (LC) rates for all patients were 92% and 85% respectively. For 111 patients with stage I NSCLC, 1- and 2-year LC was 95% and 85%, with all local recurrence (LR) occurring within 2 years. LC at 1- and 2-year was 87% for both stage II (n=19) and stage III (n=14), with all LR occurring within 10 months. For oligometastatic stage IV (n=9) patients, LC at 1- and 2-year was 71%, with all LR occurring within 5 months. Two-year LC among patients with tumors <1 cm was 100% compared to 84% for those with tumor size >1 cm. Tumor histology, prescribed dose, patient age, and prior radiotherapy (RT) or surgery had no significant impact on LC rates. Prior chemotherapy had a significant negative impact on LC with 1- and 2-year LC of 59%, compared to 1- and 2-year LC of 93% and 85%, respectively (P=0.015). n multivariate analysis, stage was the only significant predictor of LC. Among stage I NSCLC patients, 6 of 111 developed LR, 13 developed distant failures (of whom 5 also developed LR). Of these 111 patients, 5 died from NSCLC and 2 died from causes other than NSCLC; no patient died from treatment-related toxicity.
Conclusions: SBRT plays a vital role and offers excellent LC in medically-inoperable NSCLC patients, with treatment during the early stage of the disease determined as the single most significant predictor of LC on multivariate analysis.
