High-Dose-Rate Interstitial Brachytherapy for Deeply Situated Gynecologic Tumors Guided by Combination of Transrectal and Transabdominal Ultrasonography: A Technical Note

Abstract

Background and PurposeHigh-dose-rate interstitial brachytherapy (HDR-ISBT) is recommended to obtain a better local tumor control for uterine cancer patients in specific situations such as bulky lesions, an extension to the lateral parametrium, or tumors with irregular shapes. Our group uses real-time transrectal ultrasonography (TRUS) to guide freehand interstitial needle insertion. Occasionally, target tumors locate deeper beyond the rectum and cannot be visualized by TRUS. CT can guide needles to deeply located tumors, but in such cases, repeated image obtainment is required to achieve ideal needle localization. In this report, we present nine cases of patients who underwent HDR-ISBT for deeply situated tumors guided by a combination of transrectal and transabdominal ultrasonography (TR/TA-US).Material and MethodsNine uterine cancer patients whose tumors were located deeper than the reach of TRUS and underwent HDR-ISBT guided by TR/TA-US were presented. All nine cases had no distal organ metastasis and underwent external beam radiation therapy (EBRT) to the pelvic region for 45–50.4 Gy in 25–28 fractions followed by boost HDR-ISBT for deeply situated tumors guided by TR/TA-US.ResultsThere were seven cervical cancer and two endometrial cancer patients: six with extensive uterine corpus invasion, one cervical cancer with massive pelvic lymph node metastasis, one cervical cancer with postoperative pelvic recurrence, and one with left ovarian direct tumor invasion. The median follow-up period was 15 months (range 3–28 months). The average clinical target volume at the time of first HDR-ISBT was 131 ml (range 44–335 ml). The linear distance from the vaginal entrance to the deepest part of the tumor at first time brachytherapy of nine cases was 14.0 (9.0–17.0) cm. HDR-ISBT dose fractionation was 24–30 Gy in four or five fractions. Seven out of nine cases had no local recurrence in the follow-up period. One had local in-field recurrence 25 months after HDR-ISBT. Another case with carcinosarcoma could not obtain local control and underwent salvage hysterectomy for a residual uterine tumor 11 months after HDR-ISBT. Four cases had extra-field recurrence in lymph nodes or distant organs.ConclusionsIn brachytherapy for gynecologic malignancies, deeply situated tumors located out of reach of TRUS may obtain favorable local control by HDR-ISBT guided with TR/TA-US.

An Asian multi-national multi-institutional retrospective study comparing intracavitary versus the hybrid of intracavitary and interstitial brachytherapy for locally advanced uterine cervical carcinoma

“…When LC was compared between ICBT and HBT for 182 patients only with uterine body invasion, no statistically significant difference was found (4-y LC 81% vs 84.3%, P = 0.691), indicating that the current cohort of patients’ intent for using HBT was not primarily to cover the uterine body invasion. Interstitial needle insertion guided by a combination of transrectal and transabdominal ultrasonography would be an appropriate technique to navigate needle position for deeply situated tumors such as uterine body invasion in real-time fashion [ 28 ].…”

A novel multi‐modality imaging phantom for validating interstitial needle guidance for high dose rate gynecological brachytherapy

“…For those cases, a hybrid TRUS/TAUS approach may need to be considered. 22 Future work with this phantom will include incorporation of the tracking system developed by Eigen Health Services LLC to image, guide and track needles into a target volume with the goal of improving insertion position accuracy and efficiency. We hypothesize that improved accuracy via real-time tracking will reduce overall implant times by reducing the number of postinsertion images and needle repositioning.…”

“…In clinical practice, there may be cases where the rectum position does not allow TRUS visibility of deep‐seated targets. For those cases, a hybrid TRUS/TAUS approach may need to be considered 22 …”