Conformal Radiation Therapy as Definitive Treatment of Stage I Non—Small-Cell Lung Cancer: University of California San Diego Experience

Abstract

PurposeSurgical resection remains the treatment of choice for patients with stage I non—small-cell lung cancer (NSCLC). However, there is high likelihood of medical comorbidity in this patient population, requiring management by nonsurgical approaches. We report our experience using conventional and hypofractionated radiation therapy schedules with conformal approach. Patients and MethodsBetween 1991 and 2006, 108 patients with medically or otherwise inoperable stage T1/T2 N0 NSCLC were treated with curative radiation therapy alone at our institution. Patient characteristics were as follows: median age, 73 years (range, 37–86 years); male, 88/108 (81.5%); stage T2, 46/108 (42.6%), and histology/cytology, 91/108 (84.3%). Patients received a median total dose of 6500 cGy using median daily dose fractions of 250 cGy. The majority of patients were treated using hypofractionated schedules: daily dose fractions > 200 cGy, 79/108 (73.1%). The following outcomes were analyzed: local failure-free survival (LFFS; time to local failure or death from any cause), time to local or distal failure as first event, and overall survival (OS). Local failure was defined as an increase in size on imaging studies. Toxicities were evaluated using Common Terminology Criteria for Adverse Events v3.0. ResultsMedian follow-up was 19.9 months (range, 4–138.9 months). Median LFFS was 20.8 months (95% CI, 15.1–24.3 months), and median OS was 20.9 months (95% CI, 17.1–27.2 months). Analysis of competing risks showed that, at 5 years, the probability of local failure as the first detected event was 17.1% (95% CI, 10.3–25.3%), the probability of distal failure as the first detected event was 17.9% (95% CI, 11–26.1%), and the probability of death without recording a failure was 50.7% (95% CI, 40.1–60.3%). Patients aged ≥ 70 years had higher probability of death without recording a failure within 5 years (55.5%; 95% CI, 41.7% −67.3%) than patients aged < 70 years (42.6%; 95% CI, 36.4%–58%) but similar probability of local failure as first detected event (age ≥ 70 years, 14.9%; 95% CI, 7.1%–25.1%; age < 70 years, 19.9%, 95% CI 8.9% −33.9%). There was no significant difference in LFFS when comparing tertiles of dose per fractionation or presence or absence of histology/cytology at diagnosis. No patients experienced grade ≥ 4 toxicity, and only 4 patients had grade 3 toxicity. ConclusionConformal radiation therapy is an effective and safe alternative to surgery for patients with stage I NSCLC. The results are limited because this is a single-institution observational study. Nevertheless, a large majority of patients remained free of local recurrence and without significant clinical toxicity.