The Pathologic and Treatment Factors Associated With Recurrence in Stage IA Serous Adenocarcinoma of the Uterus

Abstract

The aim of this study was to evaluate the early outcomes and dose-volume parameters of a computed tomography (CT)based image-guided brachytherapy (IGBT) technique for radical treatment of uterine cervical cancer. Materials/Methods: We retrospectively reviewed the medical records of 64 patients with stage IB1-IVA cervical cancer who underwent external beam radiation therapy (EBRT) and CT-based IGBT between February 2012 and March 2014. EBRT was delivered with three-dimensional conformal radiation therapy. The initial 30-40 Gy was delivered to the whole-pelvis and then pelvic irradiation with central shielding. Total pelvis side wall dose was 50 Gy in 25 fractions. Platinum-based chemotherapy was administered concurrently to 48 patients (75%). High-dose-rate IGBT was performed in 3-4 fractions during course of the EBRT with central shielding. A planning CT scan was obtained before the delivery of each brachytherapy fraction. The high-risk clinical target volume (HR-CTV) and organs at risk (rectum and bladder) were contoured on the planning CT. The basis for the treatment plan was the initial prescription to point A. After standard loading of the source, dwell times were modified manually to maximize coverage of the HR-CTV while reducing the dose to the organs at risk. The dose constraints were D90 of the HR-CTV > 6 Gy, D2cc of the rectum < 7 Gy and D2cc of the bladder < 7 Gy. To determine the dose from the combined EBRT (whole pelvic irradiation dose excluding the fractions with central shielding) and brachytherapy, the total dose was calculated as the biologically equivalent dose expressed in 2-Gy fractions (EQD2). The relationships between the EQD2 and local control or complications were analyzed. Results: The median follow-up period was 24 months (range: 14-47 months). The median EQD2 to D90 of HR-CTV and D2cc of the rectum were 72.4 Gy (range: 56.4-100.5 Gy) and 60.9 Gy (range: 41.5-83.3 Gy), respectively. The 2-year overall survival rate, local control rate and progression-free survival rate were 97%, 89%, and 82%, respectively. Five patients (8%) experienced local recurrence and 11 patients (17%) experienced grade 1 rectal bleeding. No other grade 2 complications were observed. The incidence of local recurrence was significantly lower in patients with D90 of the HR-CTV 65 Gy vs. < 65 Gy. The incidence of grade 1 rectal bleeding was significantly higher in patients with D2cc of rectum 55 Gy vs. < 55 Gy. Conclusion: CT-based IGBT for cervical cancer achieved higher rates of local control with lower grade of complications. Dose-volume parameters exhibited significant relationships with early outcomes in CT-based IGBT.