PurposeCervical stump cancer is a carcinoma that grows on the cervical stump after a sub-total hysterectomy. There have been no studies on the application of 3D brachytherapy in cervical stump cancer. In the present study, we aimed to compare the curative effects, toxicity, and dosimetry of 3D and 2D brachytherapy in cervical stump cancer.Material and methodsThirty-one patients admitted between 2012 and 2021, who were concurrently treated with intensity-modulated radiation therapy and brachytherapy for cervical stump cancer were divided into three groups according to the brachytherapy techniques: 2D brachytherapy, 3D image-guided brachytherapy (3D-IGBT), and 2D + 3D. For patients undergoing 2D brachytherapy and 3D-IGBT, data on survival, complications, and dose to target area or organs at risk (OARs) were collected and compared. Furthermore, dosimetry difference was investigated by reconstructing the 2D plan into a 3D plan.ResultsThe median follow-up duration of all patients was 58 months. The overall 5-year progression-free survival, overall survival, and local control rates were 69.6%, 90.2%, and 78.2%, respectively. Late complications in the rectum, sigmoid colon, and bladder were milder in 3D brachytherapy than in 2D brachytherapy. Concerning the D90 value of clinical target volume (CTV) and D2cm3 value of OARs in EQD2, the 3D brachytherapy provided a lower dose to CTV (76.5 Gy vs. 95.9 Gy, on average) and OARs compared with 2D brachytherapy.ConclusionsDespite lacking statistical significance, 3D brachytherapy showed better outcomes regarding late toxicity than 2D brachytherapy, owing to the lower dose coverage in the bladder, rectum, sigmoid colon, and small intestine.