Dose–volume parameters and local tumor control in cervical cancer treated with central-shielding external-beam radiotherapy and CT-based image-guided brachytherapy

Abstract

Definitive radiotherapy for cervical cancer consists of external-beam radiotherapy (EBRT) and brachytherapy. In EBRT, a central shield (CS) reduces the dose to the rectum and bladder. The combination of whole-pelvic (WP)- and CS-EBRT and brachytherapy is the standard radiotherapy protocol in Japan. Despite clinical studies, including multi-institutional clinical trials, showing that the Japanese treatment protocol yields favorable treatment outcomes with low rates of late radiation toxicities, dose–volume parameters for the Japanese treatment protocol remain to be established. We conducted a retrospective dose–volume analysis of 103 patients with uterine cervical cancer treated with the Japanese protocol using computed tomography–based adaptive brachytherapy. The 2-year overall survival and 2-year local control rates according to FIGO stage were 100% and 100% for Stage I, 92% and 94% for Stage II, and 85% and 87% for Stage III–IV, respectively. Late adverse effects in the rectum and bladder were acceptable. Receiver operating characteristic analysis discriminated recurrence within the high-risk clinical target volume (HR-CTV) (n = 5) from no local recurrence (n = 96), with the optimal response obtained at a dose of 36.0 GyEQD2 for HR-CTV D90 and 28.0 GyEQD2 for HR-CTV D98. These values were used as cut-offs in Fisher exact tests to show that high HR-CTV D90 and HR-CTV D98 doses for brachytherapy sessions were significantly associated with tumor control within the HR-CTV. These data suggest a contribution of brachytherapy to local tumor control in WP- and CS-EBRT and brachytherapy combination treatment, warranting validation in multi-institutional prospective studies.

Cervical Stump Cancer Treated With Radiotherapy Using Computed Tomography-Guided Brachytherapy

“…As a result, the five-year local control rate for stage III-IVA patients was as high as 90%, with no rectal toxicity greater than Grade 2 over a median follow-up of 60 months. Meanwhile, Okazaki et al reported the outcome of definitive chemoradiotherapy using CT-based IGBT for 103 patients with locally advanced cervical cancer [ 15 ]. That study aimed to achieve a HR-CTV (D90) of >6 Gy at each brachytherapy session, with a total EQD2 to the rectum (D2cc) of <75 Gy.…”

Rectovaginal fistula in a cervical cancer patient treated with sequential radiotherapy and bevacizumab: A dose‐volume analysis

“…We found that the total EQD2 3 to D 2cc for the fistulated part of the rectum was 57.7 Gy and that the fistulated part was not corresponding to the dose hotspot represented by the D 2cc of the whole rectum. This value of 57.7 Gy is unexpectedly low considering the data on dose‐volume constraints and the resultant rectal toxicity reported in previous studies (performed in the pre‐bevacizumab era), which employed the same radiotherapy strategy as used herein 3,13 . Ohno et al reported the outcome of definitive chemoradiotherapy for stage IB1–IVA cervical cancers (n = 80) 3 .…”

“…This value of 57.7 Gy is unexpectedly low considering the data on dose-volume constraints and the resultant rectal toxicity reported in previous studies (performed in the pre-bevacizumab era), which employed the same radiotherapy strategy as used herein. 3,13 Ohno et al reported the outcome of definitive chemoradiotherapy for stage IB1-IVA cervical cancers (n = 80). 3 In that study, the dose-volume constraint for the rectum was set at a total EQD2 3 to D 2cc of < 75 Gy, and no rectal toxicity greater than Grade 2 was observed after a median follow-up of 60 months.…”

“…Okazaki et al reported the outcome of definitive chemoradiotherapy for stage IB1-IVA cervical cancers (n = 103). 13 In that study, the dose-volume constraint for the rectum was set at a total EQD2 3 to D 2cc of ≤ 70 Gy, and the 2-year incidence of rectal toxicity greater than Grade 2 was 2%. Taken together, these data indicate that conventional dose-volume constraints cannot be used to predict gastrointestinal fistula after sequential radiotherapy plus bevacizumab.…”

Oral Gastrografin Facilitates Delineation of Intestinal Tracts in CT-Based Brachytherapy for Uterine Cervical Cancer

“…In the treatment planning of CT-based 3D-IGBT, dose prescription is performed based on the 3D-reconstructed volumes of the high-risk clinical target volume (CTV HR ) and those of the organs at risk (OARs), such as the sigmoid colon, the rectum, and the bladder [7,8]. CT-based 3D-IGBT achieves favorable tumor local control with minimal adverse effects on OARs [8,9].…”