An Asian multi-national, multi-institutional, retrospective study on image-guided brachytherapy in cervical adenocarcinoma and adenosquamous carcinoma.

Purpose: There are limited reports on outcomes of three-dimensional image-guided brachytherapy (3D-IGBT) for cervical adenocarcinoma in Asia. In a multi-institutional retrospective study, we assessed the clinical outcomes of three-dimensional image-guided brachytherapy for cervical adenocarcinoma or adenosquamous carcinoma (CA/CAC) in Asian countries. Material and methods: Patients who had undergone definitive radiation therapy/concurrent chemoradiotherapy for untreated cervical cancer between 2000 and 2016 were registered. Those who had undergone 3D-IGBT for histologically proven CA/CAC were included. Data on patients' characteristics and treatment were collected, including tumor reduction rate (defined as a percentage of reduction in tumor size before brachytherapy compared with that at diagnosis) and high-risk clinical target volume D90. Overall survival (OS), local control (LC), and progression-free survival (PFS) rates were calculated using Kaplan-Meier method. Late toxicities were assessed using common terminology criteria for adverse events version 4.0. Results: Anonymized data of 498 patients were collected. Of the 498 patients, 36 patients met inclusion criteria. The median follow-up period was 39 months. The 3-year OS, LC, and PFS rates were 68.4%, 68.5%, and 44.4%, respectively. After treatment, five patients had tumor re-growth without complete disappearance of the tumor. Two patients developed grade 3 vaginal toxicity or grade 4 rectal toxicity; none developed other severe late toxicities. A tumor reduction rate of > 26.3% was the only significant factor in multivariate analyses, and was associated with significantly better OS (p = 0.018), LC (p = 0.022), and PFS (p = 0.013). There were no significant trends in local control or dose to high-risk clinical target volume D90. Conclusions: LC rate of CA/CAC was insufficient despite 3D-IGBT. Meanwhile, tumor reduction rate was associated with LC, OS, and PFS rates. Therefore, CA/CAC may require a different treatment strategy than that applied in cervical squamous cell carcinoma.