An Update of a Prospective Study of SBRT for Post-chemoradiation Residual Disease in Stage II/III Non-small Cell Lung Cancer

Publication date: Available online 29 July 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Sameera Kumar, Jonathan Feddock, Xingzhe Li, Andrew J. Shearer, Logan Hall, Brent J. Shelton, Susanne Arnold, Ronald C. McGarry
Purpose/Objective(s)Chemoradiation (CRT) remains standard of care for Stage III NSCLC, although local recurrences are a significant problem. Previously, we reported prospective results of the feasibility and safety of dose escalation by the addition of a stereotactic boost (SBRT) to residual disease following standard CRT. Here we report extended term outcomes for risk of late toxicities, local control and survival.Materials/MethodsPatients with stage IIB/III NSCLC underwent CT or PET-CT screening approximately one month following completion of CRT. Limited residual disease (≤ 5 cm) within the site of the primary tumor received an SBRT boost of either 10 Gy X 2 fractions or 6.5 Gy X 3 to the primary tumor in order to achieve a total (BED10) >100 Gy.ResultsThirty-seven patients received protocol therapy. With a median follow-up of 25.2 months, the crude local control rate for the entire group was 78% (n=29), but 10 (29%) and 24 (65%) patients developed regional and metastatic disease, respectively. At last follow-up, 5 (13.5%) patients remain alive, all with no evidence of disease while twenty-seven (73%) died of disease, and the remaining 5 (13.5%) died of other causes. Median overall survival (mOS) for the entire group was 25.2 months. Predictors for Grade 3 pneumonitis included age and mean lung dose. Poorer mOS was associated with histology, mOS 15.6 months for squamous cell vs 34.8 months for other histologies (large cell neuroendocrine tumors excluded) (p=0.04). The median progression free survival (mPFS) was 6 months with IIIB disease having significantly worse mPFS (Stages IIB/IIA being 9.4 months versus 4.7 months for Stage IIIB (p=0.03)).ConclusionSBRT boost following CRT is a safe treatment resulting in improvements in local control for locally advanced NSCLC. No additional late toxicities were seen. Possible improvement in OS was found, but further study in a larger prospective trial is needed.

Teaser

Chemoradiation (CRT) remains the standard of care for Stage III NSCLC although local recurrences are a significant problem. Dose escalation of radiation has met with mixed results. Given the success and safety of SBRT in early stage NSCLC, this manuscript describes the long term safety and results of adding an SBRT boost to CRT in an effort to escalate the dose of RT to the primary mass in patients with Stage II-III NSCLC.


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