Stereotactic body radiotherapy (SBRT) for non- pathologically diagnosed lung cancer patients

Abstract

Objective: Medically inoperable patients with primary or recurrent lung cancer are increasingly being diagnosed clinically without pathologic confirmation especially for patients with comorbidities that preclude biopsy. The objective of this study is to report the outcomes of medically inoperable patients with unbiopsied primary or recurrent lung carcinoma with SBRT.
Methods: From 2008-2011, 22 patients with non-pathologically diagnosed primary or recurrent lung cancer were treated with SBRT. All patients had diagnostic imaging clinically consistent with primary or recurrent lung malignancy. Fifteen patients had primary lung cancer and 7 had recurrent disease previously treated with surgery or fractionated radiotherapy. Median SBRT dose was 50 Gy (Range 40-55 Gy) in a median of 5 fractions (Range 4-10 fractions). Median BED was 100 Gy (Range 72-151.2 Gy).
Results: Median follow up is 15.3 months (Range 6.6-33.0 months). Primary tumors had a median longest dimension on the original CT of 1.6cm, which enlarged to 2.0cm (P<0.001) on serial CT and decreased to 1.3cm (P=0.003) after SBRT. Recurrent tumors had a median longest dimension of 1.6cm, which increased to 2.7cm (P=0.33) on repeat CT and subsequently stabilized at 2.7cm after SBRT. On FDG-PET scan, median standard uptake value (SUV) for the entire population is 5.4 before SBRT which decreased to 2.3 (P<0.001) after treatment. For the entire population, absolute local control was 90.9%. Kaplan-Meier curves estimates at 2 years show regional control 100%, distant control 75%, cancer specific survival 92%, and overall survival 75%. There were no grade 3/4 acute or chronic treatment-related toxicities.
Conclusions: In medically inoperable patients, a diagnosis of lung cancer can be provisionally made radiographically without pathologic confirmation. Local control can be achieved with minimal toxicity with the use of SBRT.