Three-Dimensional Non-Coplanar Conformal Radiation Therapy With 75 Gy/25fr/5w Regimen for the Treatment of Stage I NSCLC: A 10-year Experience

Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) has been demonstrated to be an acceptable alternative to surgery for early stage lung cancer in non-surgical candidates. However, there is a concern regarding declining pulmonary function tests (PFT) in some patients after this treatment modality. We undertook a retrospective review of our experience in the treatment of this population. Specifically, we recorded the changes in forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and diffusing lung capacity (DLCO) before and after SBRT. These changes were then correlated with possible predictive factors. Materials/Methods: A total of 107 patients with lung malignancies were treated with SBRT between January 2010 and December 2012 at the Juravinski Cancer Center in Hamilton, ON. Age, Charlson-Comorbidity Index, radiation dose, baseline PFTs, smoking history, planning target volume, and post-treatment PFTs were collected. Multivariate regression analysis was done to determine predictive factors in the PFT changes. Results: The median age and follow-up time was found to be 73.7 years and 9.2 months respectively. The median SBRT dose was 48 Gy in 4 fractions. The mean change in FEV1 after SBRT was 0.27 L/sec and in FVC was 0.29 L. Smoking history was the strongest predictive factor in the decline of FEV1 and FVC (p Z 0.008 and p Z 0.047). Furthermore, baseline FEV1 and FVC also correlated with a decrease in the FEV1 and FVC post-SBRT (p Z 0.005 and p Z 0.007 respectively). The PTV volume was also found to cause a statistically significant change in the FVC (p Z 0.02) and trended towards statistical significance in predicting FEV1 changes (p Z 0.07). DLCO was not significantly affected by this treatment modality. Conclusions: SBRT for lung malignancies appear to affect mildly in some patients their PFTs. Predictive factors of these changes are mostly their smoking history and pre-SBRT PFT values. PTV also predicted changes in some subset of the PFTs. Author Disclosure: N. Nguyen: None. T. Tsakiridis: None. H. Zhang: None. S. Anand: None. G. Okawara: None. T. Corbett: None. J. Wright: None.