Clinical Outcomes Following Stereotactic Body Radiation Therapy (SBRT) for Stage I Medically Inoperable Small Cell Lung Carcinoma

Abstract

Objectives: To utilize the RSSearch Patient Registry (RSSPR) to examine local control (LC), overall survival (OS), and toxicities following stereotactic body radiation therapy (SBRT) for stage I (T1-T2/N0) medically inoperable small cell lung carcinoma (SCLC). Materials and Methods: We searched the RSSPR for medically inoperable stage I SCLC patients treated with definitive SBRT. Potential predictive factors of OS were estimated using the Kaplan-Meier method as well as a Cox proportional hazards model. Results: Twenty-one patients were identified with medically inoperable stage I SCLC that met inclusion criteria. Fourteen patients had stage IA SCLC (T1N0) and 7 patients had stage IB SCLC (T2N0) with a median gross tumor volume of 10.1 cm3 (range: 0.72 to 41.4 cm3). The median number of fractions was 4 (range: 3 to 5), and the median BED10 was 105.6 Gy10 (range: 72 to 239.7 Gy10). Four patients received adjuvant chemotherapy. One- and 2-year actuarial OS rates were 73.1% (95% confidence interval [CI]: 36.8%-90.1%) and 36.6% (95% CI: 9.0%-65.7%), respectively. Factors found to be associated with 1-year OS on univariate analysis included T2 disease (85.5% vs. 33.3%; P=0.03), adjuvant chemotherapy (100% vs. 66.3%; P=0.11), and gross tumor volume ≥10 cm3 (100% vs. 52.5%; P=0.10). On multivariate analysis, adjuvant chemotherapy was associated with improved OS (hazard ratio=0.07 [95% CI: 0.13-0.37; P=0.002]). The 1-, 2-, and 3-year LC rates were 100%, and 1- and 2-year progression-free survival (PFS) rates were 85.7% (95% CI: 33.4-97.9%) and 42.9% (95% CI: 1.1-85.3%), respectively. Similar to OS, patients with T1N0 disease had superior PFS as compared to T2N0 disease (P=0.01). Toxicities were reported by 3/21 (14.3%) of patients with none ≥ grade 3 and no esophageal toxicities. Conclusions: SBRT was well-tolerated in the treatment of stage I SCLC with excellent LC achieved. Patients with T1N0 stage IA SCLC were noted to have improved PFS and OS following SBRT as compared with T2N0 Stage IB SCLC. Adjuvant chemotherapy was found to result in improved OS for stage I SCLC patients over SBRT alone.

Stereotactic Ablative Body Radiotherapy Versus Conventionally Fractionated Radiotherapy for early Stage Large Cell Neuroendocrine Carcinoma of the Lung

“…Typically, SABR is not used in SCLC considering the rarity of early stage disease. Nevertheless, a multi-institutional registry study examined outcomes in 21 inoperable patients with SCLC treated to a median dose of 48 Gy in four fractions, with only four patients going on to systemic therapy [ 4 ]. Local control was not reported, but 1-year survival was 73% potentially a reflection of distant spread.…”

“…However, to date, nearly all studies on the subject of SABR in NSCLC have focused on more common histologies, such as squamous cell carcinoma and adenocarcinoma. Recent evidence has also suggested a potential role for SABR in treatment of early stage SCLC as well [ 4 ], however the efficacy and utilization patterns of SABR in LCNEC remains relatively unknown. Considering the paucity of evidence regarding SABR in LCNEC, we analyzed the national cancer database (NCDB) to examine trends in the use of SABR and compare outcomes in patients with LCNEC receiving SABR versus CFRT.…”

A Propensity-Matched Analysis of Survival of Clinically Diagnosed Early-Stage Lung Cancer and Biopsy-Proven Early-Stage Non-Small Cell Lung Cancer Following Stereotactic Ablative Radiotherapy

“…Raj et al. reported that for the patients with early-stage SCLC following SBRT, the 1-year and 2-year OS were 73.1% and 36.6%, respectively, and the 1-, 2-, and 3-year LC rates for the cohort were 100% ( 35 ). In the future, Radiomics model may provide an effective method to distinguish between NSCLC and SCLC clinically ( 36 ).…”

“…Recently, there were an increasing of evidences for radiation oncologists to choose SBRT as reasonable treatment for patients with early-stage SCLC (34). Raj et al reported that for the patients with early-stage SCLC following SBRT, the 1-year and 2-year OS were 73.1% and 36.6%, respectively, and the 1-, 2-, and 3-year LC rates for the cohort were 100% (35). In the future, Radiomics model may provide an effective method to distinguish between NSCLC and SCLC clinically (36).…”

Single-fraction stereotactic ablative body radiation therapy for primary and metastasic lung tumor: A new paradigm?

“…In 2005[ 26 , 27 ], the first published experiences began to appear using single fraction radiation therapy in lung, in which doses of 30-34G achieved local response rates at one-year of 93%, with a G3 toxicity of 2%.…”