2. Materials and methods
2.1 Patients andimage datasets
This retrospective study enrolled a cohort of 257 LACC patients treated with intensity-modulated radiotherapy (IMRT) in Xiangya Hospital between 2014 and 2017 (Table 1). Patient inclusion criteria were as follows: (a) patients had histologically proven carcinoma of the uterine cervix, staged IB2-IVA [26]; (b) patients were treated with pelvic external beam radiotherapy (EBRT) and subsequent brachytherapy with or without concurrent chemotherapy; (c) patients who received repeated pelvic MRI 3 months after the end of radiotherapy. Exclusion criteria were as follows: (a) patients who underwent neoadjuvant chemotherapy or radical surgery before radiotherapy; (b) patients with a diagnosis of other cancers; (c) patients with no available planning CT images.
The planning CT images were acquired using a Siemens CT scanner (SOMATOM Definition AS) with scanning voltages, tube currents, and exposure time of 100-140 kVp, 39-473 mA and 500-1000 ms, respectively. The pixel sizes of the CT images were 0.7 mm × 0.7 mm to 1 mm × 1 mm; the slice thicknesses range from 3 mm to 5 mm.
We also collected 88 of 257 cases with available fat-suppressed contrast-enhanced MRI T1-weighted images to compare the performance of CT and MRI radiomic features. Details are in Supplementary Materials.
2.2 Treatment regimen
All patients underwent EBRT followed by high-dose-rate intravaginal irradiation. EBRT was administered with a daily fraction of 1.8 Gy, 5 days a week, 25-28 times with a total dose of 45-50.4 Gy. For patients with positive para-aortic lymph nodes, extended-field radiotherapy that covered both the pelvis and the para-aortic nodal region was delivered. High-dose-rate intravaginal irradiation was delivered with a fraction of 6 Gy (twice per week) for a total dose of 30–36 Gy after EBRT.
The concurrent chemotherapy consisted of two main regimens: 1) Weekly single-agent cisplatin regimen repeated at 7-day intervals for four to six cycles; 2) Triweekly combination regimen, repeated at 21-day intervals for 1-3 cycles. Adjuvant chemotherapy regimen consisted of the combination of docetaxel (75 mg/m2) and cisplatin (75 mg/m2), repeated at 21-day intervals after completion of CCRT. Patients with liver/kidney dysfunction and other conditions were administrated with radiotherapy alone. The decision on the administration of adjuvant chemotherapy was based on the status of tumor regression.