MucoUp® as a spacer in brachytherapy for uterine cervical cancer: A first-in-human experience

•MucoUp®, a hyaluronic acid, was used for the first time as a spacer in brachytherapy for uterine cervical cancer.•The study found that MucoUp® can be safely used in gynecologic brachytherapy to create space between CTVHR and OARs, without causing any significant side effects.•MucoUp® insertion enabled the median total CTVHR D90 to exceed 80 Gy while achieving dose constraints of OARs. We first used MucoUp®, a hyaluronic acid used in endoscopic resection, as a spacer in brachytherapy. In five cervical cancer patients, MucoUp® insertion increased a 90% dose of the high-risk CTV to over 80 Gy while decreasing the dose of organs at risk. No related adverse events were observed.