Stereotactic body radiotherapy (SBRT) for central and ultracentral node-negative lung tumors

Advancements in imaging and radiotherapy (RT) techniques have allowed for remarkably precise delivery of high radiation dose per treatment fraction to intrathoracic targets. As a non-invasive therapeutic modality (compared to surgery), stereotactic body radiotherapy (SBRT) is an attractive option for patients with early-stage non-small cell lung cancers and oligometastases, especially for older patients with significant comorbidities and pre-existing pulmonary dysfunction. However, the outcomes and side effect profile of SBRT are highly dependent on tumor location, especially if the tumor is located centrally (within 2 cm of the proximal bronchial tree (PBT)] or ultracentrally (touching or within 1 cm of the mediastinum, esophagus, and PBT). In this focused review, we will examine the contemporary practice and principles of using hypofractionated RT or SBRT for central and ultracentral thoracic tumors. We will identify future directions on how this practice may be incorporated into the increasingly complicated modern paradigm of lung cancer treatments which now include immunotherapy along with proton beam radiotherapy.