Stereotactic body radiotherapy for recurrent or oligometastatic uterine cervix cancer: A cooperative study of the Korean radiation oncology group (KROG 14-11)

Aim: To evaluate local control and patient survival for recurrent or oligometastatic uterine cervical cancer treated with stereotactic body radiotherapy (SBRT) using CyberKnife, and to demonstrate the safety of SBRT. Patients and Methods: Between 2002 and 2013, 100 recurrent or oligometastatic lesions in 85 patients were treated with SBRT at three Institutions. SBRT sites were within the previous RT field in 59 and partially overlapped in nine. SBRT sites included three local recurrences, 89 lymph node metastases, and eight distant metastases. Patients were treated with a median dose of 39 Gy in three fractions, which was equivalent to a biologically effective dose (BED) of 90 Gy. Results: The median follow-up period was 20.4 months. Local failure occurred in 17 out of 100 SBRT-treated sites. The 2-year and 5-year local progression-free survival rates were 82.5% and 78.8%, respectively. Eleven local failures occurred within the previous RT field. The 2-year and 5-year overall survival rates were 57.5% and 32.9%, respectively. BED >90 Gy (p=0.072) and >69 Gy (p=0.059) and longer disease-free interval (p=0.065) predicted marginally superior local control. Re-irradiation appeared to be related to inferior local control (p<0.001), but the SBRT BED in this group was much lower than the dose in the other group (median BED, 79 Gy vs. 90 Gy). Chronic toxicities of grade 3 or more occurred in five cases. Conclusion: SBRT for recurrent or oligometastatic cervical cancer resulted in excellent local control, especially with a long disease-free interval and high BED treatment, with acceptable toxicities. Therefore, SBRT can be considered a therapeutic option for these patients.