PURPOSE: We previously designed three-dimensionally-printed needle guides (3D-NG) for cervical cancer brachytherapy, which improved procedure efficiency and tumor coverage while achieving similar organs at risk (OAR) sparing compared to non-3D-printed techniques (non-3D). The subject of this study was whether 3D-NG can help improve local control and other brachytherapy outcomes. METHODS: This single institution cohort study includes 130 patients who underwent definitive external-beam radiotherapy and high-dose-rate intracavitary +/- interstitial brachytherapy from February 2017 to July 2023. 3D-NG were implemented for all cases after December 2019 (N = 77). Non-3D included applicator-only/no-needles (N = 28) or freehand-placed needles (N = 25). RESULTS: Median follow-up was 24 months. 3D-NG, versus non-3D, achieved higher mean D90 (+5.2 Gy, p <
0.001), D98 (+4.3 Gy, p <
0.001), and V100 CONCLUSIONS: 3D-NG for cervix brachytherapy were associated with improved 2-year LF compared to non-3D/freehand-needles, with higher achievement of EMBRACE II goals for D90 and D98, with similar OAR doses. This study highlights the potential for 3D-NG to simplify needle insertion while simultaneously improving needle position, dosimetry, and disease control outcomes.