Outcome with Stereotactic Body Radiation Therapy for Stage I Non–Small Cell Lung Cancer Using 5 Fractions: Single Institution Experience of 106 Consecutive Patients

Stereotactic body radiation therapy (SBRT) has been developed as a novel modality for early stage non–small cell lung cancer (NSCLC) and has emerged as a standard treatment option for medically inoperable patients. We report here our institutional experience with SBRT for stage I NSCLC. We retrospectively analyzed 106 consecutive stage I (T1a, T1b, T2a N0) NSCLC patients treated at an institution from January 2008 through December 2012 with a 5-fraction SBRT regimen. Patients were treated using the ExacTrac® system on a Novalis LINAC. Survival and loco-regional control were calculated from the date of completion of SBRT to last date of follow-up/death. There were 58 males and 48 females with median age of 76.5 years (range 50-91 years). Pulmonary and/or cardiac co-morbidity was the most common reason for patients not undergoing surgery. Eighty-seven percent (n=93) had a pathologic diagnosis whereas 13 refused biopsy. Adenocarcinoma (51%) was the most common histology followed by squamous cell (19.8%), BAC, and large cell. Sixty-nine percent (n=74) were 11-20 mm in size, 20.8% (n=22) were 21-30 mm, 2.8% (n=3) were 31-40 mm, and 6.6% (n=7) were <10 mm. Ninety-eight percent (n=104) of tumors were peripherally located whereas 1.9% (n=2) were central or para-spinal in location. The 1-, 2-, and 5-year local control (LC) rates were 98%, 90%, and 88% with all local failures (LF) occurring within 2 years. Age, gender, tumor size, tumor histology, prescribed dose, patient age, prior RT, or surgery had no significant impact on LC rates. The overall survival (OS) rates and cause specific survival (CSS) were 95%, 85%, 73%, and 41% (median survival of 42.7 months) and 98%, 91%, 81%, and 58% (median survival was not reached) at 6 months, 1 year, 2 year, and 5 years, respectively. On univariate analysis, age, gender, prescribed dose, size of tumor, and prior treatment were not significant; progression of disease was the only significant factor for OS (P<.0004) and CSS (P<.00001). Six of 106 developed LF and 13 developed distant failure (of whom 5 also developed LF). Five died from NSCLC and 2 died from causes other than NSCLC. All patients tolerated SBRT well: 21% (n=19) patients developed grade II radiation changes on follow-up CT and 12% (n=12) patients developed symptomatic radiation pneumonitis requiring medical treatment. No patient died from treatment-related toxicity. For patients with stage I NSCLC, SBRT results in excellent LC, OS, and DSS at 1, 2, and 5 years with no grade ≥III toxicity.