Tumor Boost Using External Beam Radiation in Cervical Cancer Patients Unable to Receive Intracavitary Brachytherapy: Outcome From a Multicenter Retrospective Study (Korean Radiation Oncology Group 1419)

Purpose We conducted this study to evaluate the outcomes of external-beam radiotherapy tumor boost (EBRT-B) in cervical cancer patients who could not receive intracavitary brachytherapy. Methods A total of 11 hospitals provided the data of patients who received EBRT-B during the period from January 2005 through October 2012. Results A total of 75 patients were included. The median radiotherapy dose was 46 Gy (range, 40–54 Gy) for whole pelvis and 24 Gy (range, 9–35 Gy) for EBRT-B. Initial tumor responses assessed at 2 to 6 months after radiotherapy were as follows: 46 with complete response, 22 with partial response, 2 with stable disease, and 3 with progressive disease. After a median follow-up time of 33 months, 30 patients (40.0%) showed disease progression including 21 (28.0%) with local progression. The 5-year local failure-free survival rate was 70.0%. Achieving complete response at the first follow-up visit and an overall treatment time of 53 days or less were significantly related to favorable local failure-free survival. The rate of grade 3 or higher toxicity was 2.6%. Conclusions Approximately 70% of patients had local tumor control after curative radiotherapy using EBRT-B. Early tumor response and overall treatment time of 53 days or less were closely associated with favorable local control.