Clinical research of the value of high-risk CTV setting on intensity-modulated radiotherapy for stage IIB-IVA cervical cancer

BACKGROUND: This study aims to evaluate the clinical efficacy and side effects of setting up a high-risk clinical target volume (CTV-hr) alongside simultaneous integrated boost intensity-modulated radiotherapy (IMRT-SIB) in patients diagnosed with stage IIB-IVA cervical cancer. METHODS: This study retrospectively analysed patients with stage IIB-IVA cervical cancer who received radical radiotherapy at the Affiliated Hospital of Qingdao University between November 2014 and September 2019. The patients were divided into experimental and control groups based on whether CTV-hr was set. All patients received a combined treatment of radiotherapy and chemotherapy. The dosage for paclitaxel was 135 mg/m(2), while for cisplatin it was 75 mg/m(2) or for carboplatin it was AUC 4–6, given in a cycle of 21 days. Radiotherapy (RT) included external beam radiation therapy (EBRT) and intracavitary brachytherapy (ICBT). In the control group, positive lymph nodes (GTV-n) were treated at a dose of 58–62 Gy/26–28 fractions(f), while clinical target volumes (CTV) were treated with a dose of 46–48 Gy/26-28f. The experimental group received a simultaneous integrated boost (SIB) to CTV-hr at a dose of 54–56 Gy/26-28f, with the same CTV and GTV-n as the control group. Both groups were combined with brachytherapy with a total dose (EQD2, the equivalent dose in 2 Gy/f) of 80-90 Gy. The study measured objective remission rate (ORR), 3-year progression-free survival (PFS) rate, 3-year overall survival (OS) rate, recurrence rate, and side effects as endpoints. RESULTS: The study enrolled 217 patients, with 119 in the experimental group and 98 in the control group. Results showed that the experimental group had a higher 3-year OS rate (87.4% vs. 71.4%, p = 0.001) and 3-year PFS rate (72.3% vs. 51.0%, p = 0.000) compared to the control group. Additionally, the experimental group had significantly lower rates of overall recurrence (26.1% vs. 50.0%, p = 0.003), in-field recurrence (15.1% vs. 36.7%, p = 0.000), and out-field recurrence(13.4% vs. 35.7%, p = 0.000) compared to the control group. All observed differences were found to be statistically significant. However, the experimental and control groups had no statistically significant difference in ORR and radiological side effects, such as radiation cystitis and enteritis (p > 0.05). CONCLUSIONS: Setting CTV-hr and performing IMRT-SIB on patients with stage IIB-IVA cervical cancer effectively increased the 3-year OS rate, 3-year PFS rate and reduced recurrence rate, with no significant differences in side effects.