The American Society for Radiation Oncology (ASTRO) issued a new clinical guideline for the use of stereotactic body radiation therapy (SBRT) in early-stage lung cancer. While SBRT is the current standard of care for peripherally located tumours in patients who cannot undergo surgery, the new guideline addresses the appropriateness of SBRT for medically inoperable patients with high-risk clinical scenarios requiring curative focused therapy. The guideline also reviews the role of SBRT for centrally located tumours because of their unique risks compared to peripheral tumours.
SBRT is an advanced type of external beam radiation therapy that uses sophisticated planning techniques to deliver an extremely high dose of radiation very precisely to a tumour. This high degree of precision makes SBRT notably effective at sparing healthy tissues surrounding the tumour, which is particularly important with lung tumours. For patients who are not fit enough for early-stage lung cancer surgery, SBRT presents a viable option for curative-intent treatment since it provides excellent outcomes with low toxicity. Compared to conventional external beam radiation therapy, which is delivered over several weeks, SBRT is typically administered in five or fewer treatment sessions, or fractions.
Drawing on data from retrospective and prospective studies and the available randomized clinical trials, the guideline provides evidence-based recommendations regarding the appropriate use of SBRT for early-stage non-small cell lung cancer (NSCLC). The principal goal of the guideline was to address SBRT for patients unable to tolerate surgery who require customization of SBRT in high-risk clinical scenarios, such as for salvage therapy after previous surgery or radiation therapy, for tumours invading the chest wall or for very large tumours. The guideline also details principles of SBRT directed toward centrally located lung tumours, since treating these tumours carries unique and significant risks when compared to treatment directed at peripherally located tumours. Additionally, although the focus of the guideline was the inoperable patient, the appropriateness of SBRT in the operable patient also was addressed, since it is an area of debate and controversy.