Dosimetry and short term effect comparison of CT-guided interstitial brachytherapy and intracavitary brachytherapy for locally advanced cervical cancer

Objective To discuss the dosimetric advantage of computed tomography-guided interstitial brachytherapy compared with the conventional intracavitary brachytherapy for locally advanced cervical cancer, offering a more advantageous clinical treatment approach. Methods Twenty-eight locally advanced cervical cancer patients with bulky tumors (tumor size>5 cm) after external beam radiotherapy received computed tomography-guided interstitial brachytherapy. Dosimetric outcomes of the current study, including the total dose (external beam radiotherapy+ brachytherapy) D90 for the HR-CTV and D2cc for the bladder, rectum, and sigmoid, were compared with a former patient group consisting of 30 patients who received the conventional intracavitary brachytherapy (uterine tandem+ ovoid pairs). Results The mean D90 value for HR-CTV in the intracavitary brachytherapy group and interstitial brachytherapy group were (76.9±5.7) and (88.1±3.3) Gy, respectively. The D2cc for the bladder, rectum, and sigmoid in the intracavitary brachytherapy group and interstitial brachytherapy group were (84.7±6.8) Gy, (69.2±4.2) Gy, (67.8±4.5) Gy and (81.8±6.5) Gy, (6.8±4.0) Gy, (64.8±4.1) Gy, respectively.1-year local tumor control rate in the intracavitary brachytherapy group and interstitial brachytherapy group were 59.3% and 85.2%, respectively. Conclusions CT-guided interstitial brachytherapy shows a significant dosimetric advantage compared with the conventional intracavitary brachytherapy, and is, thereby, clinically possible feasible. However, the long term curative effect and toxicity need to be further investigated. Key words: Cervical neoplasms/brachytherapy; Brachytherapy, interstitial; Brachytherapy, intracavitary; Dosimetry