Stereotactic body radiation therapy for medically inoperable early-stage lung cancer: Tata Memorial Hospital perspective and practice recommendations

Background: Stereotactic body radiotherapy (SBRT) is now considered the standard treatment for medically inoperable early-stage non-small lung cell cancer (ES-NSCLC). Purpose: There is a paucity of data related to outcomes with SBRT in ES-NSCLC from the developing countries. We report the early outcomes of ES-NSCLC patients treated with SBRT at our institute. Materials and Methods: Between 2007 and 2015, 40 consecutive patients with histologically proven ES-NSCLC were treated with SBRT. Median age was 71 years (range: 46-88 years) and median Charlson comorbidity index (CCI) was 3. The majority had stage I (70%) and 45% of the tumors were centrally located. The median tumor diameter was 3.8 cm (range: 2-7.6 cm). The mean gross tumor volume was 41 cc (range: 4-139 cc) and the mean planning target volume (PTV) was 141 cc (range: 27-251 cc). Varying dose and fraction (fr) sizes were used depending on tumor location, tumor size, and treatment period. The median biologically effective dose (BED) was 77 Gy(10) (range: 77-105 Gy(10)) for the initial cohort (2007-2012) and 105 Gy(10) (range: 77-132 Gy(10)) for the subsequent cohort (2013-2015). Results: After a median follow-up of 16 months (range: 3-99 months), the 2-year local control (LC), overall survival, and cancer-specific survival (CSS) rates were 94%, 41%, and 62%, respectively. The univariate and multivariate analysis determined CCI >3 and PTV >80.6 cc as significant predictors of worse OS and CSS (P < 0.01). The clinical stage, tumor location, BED, and treatment period (2007-2012 vs. 2013-2015) did not significantly predict any of the outcomes. The most common acute toxicities were skin erythema (10%), grade 1 esophagitis (8%), and exacerbation of previous chronic obstructive pulmonary disease (10%). Grade >= 2 late radiation pneumonitis was seen in 17.5%. One patient developed a rib fracture. No neurological or vascular complications were seen. Conclusions: SBRT results in excellent local control (LC) and acceptable survival in medically inoperable ES-NSCLC with minimal adverse effects. Charlson comorbidity index and target volume are important prognostic factors and may aid in patient selection.