Stereotactic body radiation therapy (SBRT) for centrally located primary and recurrent non-small cell lung cancer (NSCLC): analysis of toxicity and local control

Stereotactic body radiation therapy for centrally located lung tumors has been associated with increased risk of toxicity. A current study aims to evaluate tumor control and toxicity in large cohort of centrally located lesions.

Central location was defined as tumors within 2 cm of the bronchial tree, trachea, major vessels, esophagus, heart, pericardium, brachial plexus, or vertebral body. Tumors were biopsy proven or PET positive and included recurrent or primary non-small cell lung cancer (NSCLC). A dose was prescribed to a non-uniform planning target volume based on the internal tumor volume constructed from a 4D CT scan allowing for tumor motion. The treatment plans consisted of non-coplanar static aperture arcs and non-coplanar static fields. Treatments were delivered using 6MV X-rays with image guidance.

At a median follow-up of 12.3 months, 107 total NSCLC tumors were retrospectively reviewed. A cohort consisted of primary (n = 57) and recurrent (n = 50) NSCLC tumors with subset of recurrent lesions including 27 hilar or mediastinal lymph nodes. Median and most frequent dose were 45 Gy in four fractions treated once weekly. Estimated 2-year Kaplan-Meier survival was 81.7%, with a significant survival advantage between primary and recurrent (p = 0.003). Eleven patients failed locally giving a 2-year actuarial local control rate of 80.7%, with control rates of 82.5 and 79.2% for primary and recurrent tumors, respectively (p = 0.828). Regional control at 2 years was not significantly different for primary (72.6%) and recurrent (62.7%). Analysis of toxicity revealed no grade 4 or 5 events. One grade 3 event was reported as pneumonitis. Grade 2 toxicity occurred in 10 patients, including dyspnea (1), chest wall pain (2), pneumonitis (4), rib fracture (1), and cough (2).

Moderate prescription dosing, treated once weekly, offers acceptable local control rates for centrally located tumors including recurrent mediastinal and hilar lymph nodes. Toxicity was minimal with the majority of patients experiencing no treatment-related adverse events.