Trans-rectal ultrasound-guided hybrid intra-cavitary and interstitial brachytherapy in carcinoma cervix: A feasibility study from a tertiary cancer center in India.

PURPOSE: To report the feasibility of performing hybrid intra-cavitary and interstitial (IC/IS) brachytherapy in patients with carcinoma cervix under trans-rectal ultrasound (TRUS) guidance.

MATERIAL AND METHODS: All patients who received an external beam radiotherapy (EBRT) dose of 50 Gy in 25 fractions with weekly chemotherapy, followed by a brachytherapy boost (21 Gy in 3 fractions) were prospectively included for analysis. IC/IS brachytherapy was performed using Fletcher style tandem and ovoid applicator with interstitial component under TRUS guidance. Parameters of implant quality analyzed included ability to insert tandem, ratio of needles loaded to the number of needles inserted, and incidence of uterine or organ at risk (OARs) perforation. Dosimetric parameters evaluated were dose to point A*, TRAK, D90 high-risk clinical target volume (HR-CTV), and D2cc to OARs (bladder, rectum, and sigmoid). Width and thickness of the target was compared between TRUS (TRUSw and TRUSt ) and MRI (MRIw and MRIt ).

RESULTS: Twenty carcinoma cervix patients treated with IC/IS brachytherapy were included for analysis. The mean HR-CTV volume was 36 cc. The median number of needles used were 6 (range, 2-10 needles). None of the patients had uterine perforation. Two patients had bowel and bladder perforation. The mean D90 HR-CTV and D98 HR-CTV were 87.3 Gy and 82 Gy EQD2 , respectively. The mean D2cc to the bladder, rectum, and sigmoid were 80 Gy, 70 Gy, and 64 Gy EQD2 , respectively. The mean dose to point A* was 70.4 Gy EQD2 . The mean TRAK was 0.40. The mean TRUSw (±SD) and MRIw (±SD) were 4.58 cm (±0.44) and 4.49 cm (±0.50), respectively. The mean TRUSt (±SD) and MRIt (±SD) were 2.7 cm (±0.59) and 2.62 cm (±0.59), respectively. On statistical analysis, there was a significant correlation between TRUSw and MRIw ( r = 0.93), and TRUSt and MRIt ( r = 0.98).

CONCLUSIONS: TRUS-guided IC/IS brachytherapy is feasible and provides adequate coverage of the target, with acceptable doses to OARs.