Local control for clinical stage I non-small cell lung cancer treated with 5-fraction stereotactic body radiation therapy is not associated with treatment schedule

Purpose: Clinical concern remains regarding the relationship between consecutive (QD) versus nonconsecutive (QoD) lung stereotactic body radiation therapy (SBRT) treatment schedules and outcomes for clinical stage I non-small cell lung cancer (NSCLC). We examined a multi-institutional series of patients receiving 5-fraction lung SBRT to compare the local failure rates and overall survival between patients receiving QD versus QoD treatment.

Methods and materials: Lung SBRT databases from 2 high-volume institutions were combined, and patients receiving 5-fraction SBRT for a solitary stage I NSCLC were identified. QD treatment was defined as completing SBRT in ≤7 days, whereas QoD treatment was defined as completing treatment in >7 days. To control for patient characteristics between the 2 institutions, a 1:1 propensity-matched analysis was performed. Multivariable logistic regression was performed to identify variables independently associated with local failure, and Cox proportional hazards modeling to identify variables independently associated with increased mortality.

Results: From 2005 through 2016, 245 clinical stage I NSCLC patients receiving 5-fraction SBRT were identified. A total of 117 (47.8%) patients received QD treatment and 128 (52.2%) patients received QoD treatment. On propensity-matched analysis, no association was seen between QD treatment and local failure (odds ratio [OR] for QD treatment, 0.48; 95% confidence interval [CI], 0.12-1.99; P = .5). On multivariable logistic regression, central tumors were independently associated with increased likelihood of local recurrence (OR, 5.2; 95% CI, 1.11-24.2; P = .04). Kaplan-Meier analysis identified no difference in median overall survival between QD versus QoD treatments (38.0 vs 38.0 months, log-rank P = .7), respectively. QD treatment was not associated with an increased mortality hazard (hazard ratio, 1.08; 95% CI, 0.67-1.75; P = .75).

Conclusions: This analysis demonstrated no association between QD versus QoD treatment scheduling and local control or overall survival for early-stage NSCLC.