SABR-5 is the protocol that keeps giving. This interesting secondary analysis reveals outcomes for ultracentral versus peripheral lung mets are particularly poor. Ultra-central here was defined as the target overlapping or contacting central structures such as proximal bronchial tree, esophagus, great vessels and heart. As predicted, the 41 patients with 45 ultracentral lung mets had significantly worse progression-free (HR 2.18) and even overall (HR 3.45) survival than the 93 patients with 172 non-ultracentral lung mets. Theories as to why is where things get interesting. Importantly, no grade 3 radiation toxicity was noted in either cohort so this is not a matter of treatment sequelae. The authors point to the interesting observation that the rate of polymetastatic progression at two years was more than double for the ultracentral cohort (69% versus 31%) to suggest “closer proximity to large vessels and central lymphatics could theoretically facilitate tumor dissemination “ as has been postulated to explain the more aggressive nature of ultracentral primary lung cancers. | Baker, Int J Radiat Oncol Biol Phys 2025
