Stereotactic ablative body radiotherapy boost for cervical cancer when brachytherapy boost is not feasible

Abstract

Background The purpose of this study was to analyze the treatment efficacy and safety of stereotactic ablative body radiotherapy (SABR) boost for cervical cancer patients not amenable to brachytherapy. Methods A retrospective review of the medical records from single institution of 25 eligible patients was performed. The patients underwent pelvic radiotherapy (RT) in 25 or 28 fractions with a median dose of 45 Gy (range 44–50.4 Gy). SABR boost was delivered after pelvic RT, with a median dose of 25 Gy (range 20–33 Gy), and a median fraction number of 5 (range 4–6). 21 patients with a follow-up period of more than one year were included in the toxicity analysis, and hematuria and hematochezia that occurred later than 3 months after the RT were graded. Results The median follow-up period after radiotherapy was 2.85 years (range 0.33–6.60). The 3-year local control, locoregional control, disease-free survival, and overall survival rates were 80.9%, 75.8%, 40.9%, and 77.1%, respectively. 5 patients experienced grade 3 toxicity (3 genitourinary, 3 gastrointestinal), and no grade 4–5 toxicity was reported. Univariate analysis showed that cumulative D2cc in equivalent dose in 2 Gy fractions (EQD2) of rectum was marginally predictive for any grade of hematochezia (P = 0.051). Cumulative D2cc EQD2 of bladder was not predictive for hematuria. In the receiver operating characteristic (ROC) curve analysis, the optimal threshold of cumulative rectal D2cc EQD2 was 81.2 Gy for any grade of hematochezia. Conclusion SABR boost for cervical cancer was effective and tolerable. Although it cannot substitute brachytherapy, it can be a treatment option when brachytherapy is not possible.

Stereotactic Body Radiotherapy Boost with the CyberKnife for Locally Advanced Cervical Cancer: Dosimetric Analysis and Potential Clinical Benefits

“…In the CK-CTV plan, the HR-PTV was equal to the HR-CTV of the BT plan. Considering the setup and systematic error in EBRT and tumor motion, previous studies indicated that the margin of planning target volume (PTV) from the HR-CTV was 5 mm in LACC [ 9 , 13 , 17 ]. Hence, the HR-PTV was built from the HR-CTV of the BT plan with a margin of 5 mm in the CK-PTV plan.…”

“…With the advent of radiation delivery and image-guiding techniques, stereotactic body radiotherapy (SBRT) can now deliver a substantially higher dose to defined target volumes and effectively protect organs at risk (OARs). In addition, compared with other EBRT boost techniques, a higher biologically equivalent dose can be achieved by SBRT [ 9 ]. Earlier studies indicated that SBRT could be similar to BT in clinical outcomes and minimal toxicities for patients with cervical cancer [ 10 , 11 , 12 , 13 ].…”

Role of stereotactic body radiotherapy in gynecologic radiation oncology

“…There have been few studies that have reviewed outcomes of patients who received SBRT boost in lieu of brachytherapy boost for a primary gynecologic malignancy (Table 1). A retrospective study including 25 patients with newly diagnosed cervical cancer treated with external beam radiotherapy followed by SBRT boost reported a 3-year local control rate of 80.9% with 20% of patients experiencing grade 3 toxicity including hematuria and hematochezia 4. Patients included in this analysis were unable to undergo brachytherapy boost due to either anatomic issues (ie, narrow vagina or cervical stenosis), tumor size felt to be too large for adequate brachytherapy dose distribution, morbid obesity, or other medical co-morbidities precluding brachytherapy.…”

“…A retrospective study including 25 patients with newly diagnosed cervical cancer treated with external beam radiotherapy followed by SBRT boost reported a 3-year local control rate of 80.9% with 20% of patients experiencing grade 3 toxicity including hematuria and hematochezia. 4 Patients included in this analysis were unable to undergo brachytherapy boost due to either anatomic issues (ie, narrow vagina or cervical stenosis), tumor size felt to be too large for adequate brachytherapy dose distribution, morbid obesity, or other medical co-morbidities precluding brachytherapy. The authors of this study conclude that although SBRT may not replace brachytherapy, SBRT may be a reasonable alternative if a patient is unsuitable for brachytherapy or if the procedure is not available.…”

Image-Guided Versus Conventional Brachytherapy for Locally Advanced Cervical Cancer: Experience of Single Institution with the Same Practitioner and Time Period

“…Brachytherapy is essential for better treatment outcomes of locally advanced cervical cancer [ 1 ]. Even the recently developed external beam radiation therapy (EBRT) technique cannot substitute brachytherapy [ 2 ]. A significant advancement of gynecologic brachytherapy is utilization of three-dimensional (3D) images such as computerized tomography (CT) and magnetic resonance imaging (MRI).…”