Interim Mri Provides Accurate Information Of Brachytherapy For Patients With Locally Advanced Cervical Cancer

To investigate the impact of interim MRI on outcome of cervical cancer patients treated with radical radiotherapy including series of high-dose-rate (HDR) brachytherapy (BT). We retrospectively analyzed consecutive 146 patients with locally advanced cervical cancer treated with radical radiotherapy between December 2009 and September 2015. The median dose of pelvic irradiation was 30.6 Gy (range, 30.6-39.6 Gy); further treatment used 10.8-19.8 Gy with a midline block. For all pts, the tumor size and location was diagnosed by interim MRI within 7 days before first HDR-BT. The standard intracavitary brachytherapy (ICBT) was principally administered for patients with 4 cm or smaller mass and symmetrical location on interim MRI. The selection criteria of individualized BT, which included interstitial brachytherapy (IBT), hybrid brachytherapy (HBT) and dose escalating ICBT to the high risk (HR) CTV D90, was diagnosed with interim MRI, namely 1) the width larger than 4 cm and asymmetrical tumor location, 2) the tumor with a vaginal invasion thicker than 5mm and 3) the bulky barrel shaped tumor. In case of ICBT, dose of 20-24 Gy/4 fractions were prescribed to point A or HRCTV D90. And in case of IBT, the dose of 24-30 Gy/4-5 fractions/2-3 days were prescribed to HRCTV D90. The patient characteristics were followings, median age was 57 years old (range 27-80 years old). Six pts were in FIGO stage Ib2, 67 in II, 64 in III and 9 in IVA. A total of 124 pts had squamous cell carcinoma, and 22 had adenosquamous cell carcinoma or adenocarcinoma. Median tumor size measured by initial pretreatment MRI was 52 mm (range 17-132 mm). At the time of initial pretreatment, 19 pts had severe vaginal invasion, 21 had asymmetrical tumor and 39 had corpus invasion. Median tumor size measured by interim MRI was 30 mm (range 0-78 mm). Finally, 119 pts were treated with standard ICT, 8 with dose escalated ICT, 4 with HBT and 15 with IBT. Median follow up period was 37.6 months (range 2.5-84.5 months). Complete response was obtained 139 pts (95.2%). Three-year overall survival (OS), disease free survival, local control (LC) and distant metastasis free survival were 84.2%, 75.6%, 90.1% and 81.8%, respectively. The grade 2 or 3 late rectal complications were recorded in 6 pts (4.2%). On univariate and multivariate analysis, there was no significant difference between LC and tumor characteristics such as large tumor, tumor with severe vaginal invasion, asymmetrical tumor and tumor with corpus invasion. On multivariate analysis, small tumor and local control after radiotherapy were significantly related to excellent OS (p=0.001 and <0.001, respectively). Interim MRI provides accurate radiological information to select appropriate brachytherapy method individually for patients with locally advanced cervical cancer and leads to excellent LC and OS.