Predictors and management of chest wall toxicity after lung stereotactic body radiotherapy

Stereotactic body radiotherapy is the preferred treatment modality for patients with inoperable early stage lung cancer. Chest wall toxicity is a potentially dose limiting side effect and may include fractures or pain secondary to treatment. The pathophysiology of these symptoms is unclear although it is presumed that radiation may alter the bone's normal tissue environment, affecting maintenance and remodeling. Chest wall pain is likely neuropathic secondary to injury to the intercostal nerves. Identifying patients with chest wall toxicity can be difficult due to the varying definitions of toxicity as well as heterogeneous contouring guidelines. Multiple studies have demonstrated a correlation between treatment factors and the incidence of chest wall toxicity. An increase in dose and treatment volume appear to be the most consistent radiation factors associated with toxicity. Patient factors such as body mass index, female gender, tumor location, and age have also been correlated with an increased likelihood of developing side effects. Management of chest wall toxicity is typically conservative using analgesic medications although surgical intervention may be required for displaced fractures. In this review, we examine the treatment, patient, and tumor factors predictive for chest wall toxicity and the implications for the treating physician.