Stereotactic ablative body radiotherapy boost for cervical cancer when brachytherapy boost is not feasible
Tae Hoon Lee, Changhoon Song, In Ah Kim, Kim Js, Yong Beom Kim, Kidong Kim, Jae Hong No, Dong Hoon Suh, Jin‐Beom Chung, Keun‐Yong Eom
Abstract
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 D 2cc in equivalent dose in 2 Gy fractions (EQD2) of rectum was marginally predictive for any grade of hematochezia ( P = 0.051). Cumulative D 2cc EQD2 of bladder was not predictive for hematuria. In the receiver operating characteristic (ROC) curve analysis, the optimal threshold of cumulative rectal D 2cc 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.