Toxicity After Central Versus Peripheral Stereotactic Lung Radiation Therapy (SBRT): A Propensity Score Matched-Pair Analysis

FEV1/FVC, and DLCO% were 4.2 4.9, 0.78 2.76, and -4.8 5.0 and 2.86 6.6, 0.48 2.9 and -11.7 5.9 during RT and post RT, respectively. Only DLCO had a significant decrease after RT (p Z 0.024). The reduction in DLCO measured during RT was correlated with post-RT changes (R Z 0.46). DLCO reduction after RT had an inverse correlation with the MLD (R Z -0.45). Patients with a greater reduction of DLCO (more than 10%) after RT had a higher incidence of RP compared to patients with less reduction (38% vs 23%). In this study of limited sample size, the SBRT patients did not have a statistically significant change in DLCO either during (p Z 0.55) or post (p Z 0.64) RT. SBRT patients had less of a decrement in DLCO compared to CRT patients (-2.9 12.8 vs -14.2 6.5, p Z .11 trend for pre to post, 3.85 14.6 vs -10.5 5.2, p Z 0.027 dur to post) that may be related to a trend in the decrease in MLD in SBRT plans (14.5 Gy CRT vs 9.95 Gy SBRT p Z 0.079). Conclusions: We have confirmed the previous finding that DLCO may be the most sensitive PFT parameter to evaluate lung function after RT. Radiation induced reduction in DLCO measured during RT and high MLD in RT plans appears to be predictive of a reduction in lung function and RP after radiation. We also observed that during and post RT changes in DLCO for SBRT patients were substantially less than in CRT patients. Acknowledgment: This research was supported by RO1CA142840. Author Disclosure: S. Samuels: None. M.M. Matuszak: None. D. Arenberg: None. P. Stanton: None. J. Wang: None. R.K. Ten Haken: None. J. Hayman: None. J. Curtis: None. F. Kong: None.