The selection of tandem angle and imaging during intracavitary brachytherapy of carcinoma cervix - An experience from a regional cancer center

Carcinoma cervix (CACX) is a common gynecological malignancy and locally advanced CACX is treated with radical chemoradiation, followed by brachytherapy boost. The appropriate selection of tandem angle is needed for optimal dose distribution and to avoid perforations. The aim of our study was to assess the appropriate tandem angle selection based on uterine angle measured on external beam radiotherapy (EBRT) planning imaging and to assess the need for repeat imaging and image-guided placement of tandem during intracavitary brachytherapy based on risk factors. This is a single-institute, two-arm retrospective, observational study to improve quality of brachytherapy in CACX patients (n = 206), with uterine perforation/suboptimal tandem placement (UPSTP) in arm A and optimally inserted in arm B. The uterine angle was measured from EBRT planning CT-scan and correlated with brachytherapy planning CT-scan and other risk factors in relation to UPSTP. The uterine angle was 30 (±30 ) and 17 (±21 ) on EBRT and brachytherapy planning CT-scan, respectively, and significantly was different (P < 0.00001). There were 40 (19%) perforations and 52 (25%) suboptimal tandem placements (uterine subserosal/muscle insertion). The most common site of perforation was posterior then anterior and central. There was higher chance of UPSTP with hydrometra, huge uterus with tumor (HMHU) or retroverted uterus (RU), P = 0.006 and 0.14, respectively. The persistence of HMHU or RU during brachytherapy leads to higher UPSTP, P = 0.000023 and 0.18, respectively. Uterine angle measurement on EBRT planning CT-scan varies significantly when measured on brachytherapy planning CT-scan and cannot be used for selection of tandem. Reimaging before brachytherapy should be considered in advanced CACX with HMHU or RU at presentation and image-guided placement of tandem should be used if HMHU or RU persists during brachytherapy.