Contralateral Hilar Irradiation in Lung Cancer: A Systematic Review

Management of patients with positive contralateral hilar lymph nodes (LNs) remains controversial. However, whether definitive radiotherapy (RT) can be safely and effectively administered to such patients is unclear. Therefore, we conducted a systematic review to evaluate the toxicity and efficacy of contralateral hilar irradiation in lung cancer. A literature search was conducted in MEDLINE via PubMed from database inception to March 2026. We included articles in which RT was performed for the contralateral or bilateral hilum or that reported radiological assessments of contralateral or bilateral hilar LN metastases. The primary outcome was toxicity associated with contralateral hilar irradiation (including bilateral hilar irradiation), and the key secondary outcome was overall survival (OS). Of 650 articles, 11 met the inclusion criteria. No direct toxicity data associated with contralateral hilar irradiation were available for the primary outcome. Regarding the key secondary outcome, two studies reported OS in patients with positive contralateral hilar LNs who received RT. One study using three-dimensional conformal RT (3D-CRT) reported no differences in the median survival among the N3 subcategories of limited-stage small-cell lung cancer. Another study using 3D-CRT found no differences in survival curves between patients with non-small cell lung cancer with contralateral hilar LNs and those with supraclavicular LNs. No survival data were available for contralateral hilar irradiation using intensity-modulated RT (IMRT) with or without consolidative immune checkpoint inhibitors (ICIs). The safety of definitive RT in patients with positive contralateral hilar LNs remains unclear. Further studies are necessary to determine the feasibility of IMRT with chemotherapy, followed by ICIs, under the standards of care. • Systematic review assessed toxicity and efficacy of contralateral hilar irradiation • No direct toxicity data for contralateral hilar irradiation were available • No survival data for contralateral hilar irradiation using IMRT were available • Further studies are needed to assess chemo-IMRT followed by ICIs in these patients