Stereotactic body radiotherapy (SBRT) is habitually taken with 50 Gy in 5 fractions and in some exceptions, 50 Gy in 10 fractions. A study estimated the effect of the 2 fractions on survival results and local controls. Patients served with SBRT with 50 Gy/5 and 50 Gy/10 were evaluated for metastatic NSCLC and early-stage NSCLC. A competing risk procedure was used for determining the cumulative incidence of local failure (LF). Kaplan-Meier methodology was used for determining the overall survival (OS) and Progression-Free Survival (PFS) in patients with stage I NSCLC.

About 353 lesions were taken, out of which 50 Gy/5 was used in 300 (85%) cases, whereas, 50Gy/10 was used in 53 (15%) cases. LFs at 3 years stood at 6.5% and 23.9% respectively. The LF median time as estimated by the Kaplan-Meier procedure was 17.5- and 26.2 months, respectively. Semiparametric analysis disclosed an increased planning target volume (hazard ratio 1.01, P= .04) as the sole predictor of increased LF. However, the size of the tumor, ultra-central location, and 10 fractions didn’t contribute to the LF. For patients suffering from stage I NSCLC (n = 298), the median PFS stood at 35.6 months and median OS came out to be 42.4 months. No difference was noted either in OS or PFS among the 2-treatment authority for stage I NSCLC patients. Grade 3+ toxicity was found in all patients at low rates, while 1 of them was affected with grade 3 pneumonitis after SBRT – 50 Gy/5.  When fulfilling universally recognized restrictions, dose-fractionation methods with BED10 greater than or equal to 100Gy give improved local control and should be supplied. If those regimens appear to be too risky, 50 Gy in 10 parts might be a good balance between tumor control and safety, with relatively long-lasting control and little effect on long-term life.

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Link:www.clinical-lung-cancer.com/article/S1525-7304(20)30272-2/fulltext