Objective:To evaluate the effect of tumor volume on the radiation dose and efficacy of locally advanced cervical cancer patients undergoing radical radiotherapy and chemotherapy.Methods:Clinical data of 126 patients who were diagnosed with cervical cancer (stage ⅡB-ⅣA) and underwent radical concurrent chemoradiotherapy in Guangxi Medical University Cancer Hospital from November 2019 to November 2022 were retrospectively analyzed. The cut-off values of tumor volume before (pre-TV) and after (post-TV) external radiotherapy and tumor volume reduction rate (TVRR) were calculated by Jamovi software. The effects of pre-TV, post-TV and TVRR on short-term efficacy, progression-free survival (PFS), brachytherapy (BT) mode , high-risk clinical target volume (HR-CTV) and organs at risk (OAR) dose were investigated by univariate and multivariate analyses.Results:Pre-TV≥67.03 cm 3 and post-TV≥14.88 cm 3 were poor prognostic factors for 6-month PFS and objective response rate (ORR) (both P<0.05), and post-TV was an independent prognostic factor. In the TVRR≥73.0% and <73.0% groups, no statistical differences were observed in the 6-month PFS and ORR. In the pre-TV≥67.03 cm 3 group, the cases number of intracavitary brachytherapy (ICBT) and intracavitary / interstitial brachytherapy (IC/IS-BT) was 36 (50.0%), while in the pre-TV<67.03 cm 3 group, the cases number of ICBT and IC/IS-BT was 41 (76%) and 13 (24%), respectively ( P=0.003). In the post-TV≥14.88 cm3 group, the cases number of ICBT and IC/IS-BT was 28 (47%) and 32 (53%), while 49 (72%) and 17 (26%) in the post-TV<14.88 cm3 group, respectively ( P=0.002). The dose of HR-CTV D 90% in the TVRR≥73.0% group was significantly higher than that in the TVRR<73.0% group ( P=0.014), but there was no significant difference in the dose of bladder D 2 cm3, rectal D 2 cm3 and small intestine D 2 cm3 (all P>0.05). The dose of HR-CTV D 90% in the post-TV<14.88 cm 3 group was significantly higher than that in post-TV≥14.88 cm 3 group ( P<0.001), and the dose of bladder D 2 cm3 in the post-TV≥14.88 cm 3 group was higher than that in the post-TV<14.88 cm 3 group ( P<0.05). There was no significant difference in the dose of rectal D 2 cm3 and small intestinal D 2 cm3 between two groups (both P>0.05). The number of concurrent chemotherapy (≥4 times vs.<4 times) had no statistical difference for 6-month PFS and TVRR. Conclusions:Pre-TV and post-TV are the influencing factors of short-term efficacy and BT mode selection for locally advanced cervical cancer. Post-TV is an independent prognostic factor and also indirectly affects the dose of HR-CTV D 90% and bladder D 2 cm3 Increasing the number of concurrent chemotherapy (≥4 times) does not improve TVRR and short-term efficacy.