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Purpose High-dose-rate (HDR) intraluminal brachytherapy for advanced or inoperable tumors of the rectum has been used both palliatively and to dose escalate after chemoradiation for curative treatment. Methods Between 1993 and 2007, 79 patients were treated with HDR afterloading brachytherapy for rectal cancer; 70 patients had adenocarcinoma of the rectum; and 9 patients had squamous cell carcinoma of the anal canal. Fifty-two patients had localized disease but were unfit for major surgery and received radiotherapy with radical intent. Twenty-seven patients with advanced or metastatic disease received palliative treatment. The median age was 82 years (range, 33–97). Radical treatment comprised either chemoradiation followed by intraluminal brachytherapy delivering 12 Gy at 1 cm in two fractions or radical monotherapy delivering up to 36 Gy at 1 cm in six fractions two to three times weekly. Palliative HDR brachytherapy schedules were predominantly 10 Gy at 1 cm single dose. Results Objective local tumor response was seen in 41 of 48 assessable patients (85%); of whom, 28 patients (58%) had a complete response and 13 (27%) had a partial response. The most common symptom was rectal bleeding, which was controlled with a complete response rate of 63%. The median duration of the symptom response was 3 months (range, 1–73), and the median survival of the palliative patients was 6 months (range, 1 week–37 months). The median survival for patients treated with radical intent was 18.5 months (range, 2–119). Six patients reported late toxicity with three cases of rectal ulcer, two strictures, and one fistula. Conclusions Intraluminal HDR brachytherapy is effective as local treatment in both the radical and palliative setting, with high tumor and symptom response rates, and acceptable late toxicity.

Background and purpose Fractionated high dose-rate (HDR) brachytherapy in the treatment of prostate cancer relies on reproducible catheter positions for each fraction to ensure adequate tumour coverage while minimising dose to normal tissues. Peri-prostatic oedema may cause caudal displacement of the catheters relative to the prostate gland between fractions. This can be corrected for by changing source dwell positions or by physical re-advancement of catheters before treatment. Materials and methods Data for 20 consecutive monotherapy patients receiving three HDR fractions of 10.5 Gy per fraction over 2 days were analysed retrospectively. Pre-treatment CT scans were used to assess the effect of catheter movement between fractions on implant quality, with and without movement correction. Implant quality was evaluated using dosimetric parameters. Results Compared to the first fraction (f1) the mean inter-fraction caudal movement relative to the prostate base was 7.9 mm (f2) (range 0–21 mm) and 3.9 mm (f3) (range 0–25.5 mm). PTV D90% was reduced without movement correction by a mean of 27.8% (f2) and 32.3% (f3), compared with 5.3% and 5.1%, respectively, with catheter movement correction. Dose to 2 cc of the rectum increased by a mean of 0.69 (f2) and 0.76 Gy (f3) compared with an increase of 0.03 and 0.04 Gy, respectively, with correction. The urethra V12 also increased by a mean of 0.36 (f2) and 0.39 Gy (f3) compared with 0.06 and 0.16 Gy, respectively, with correction. Conclusions Inter-fraction correction for catheter movement using pre-treatment imaging is critical to maintain the quality of an implant. Without movement correction there is significant risk of tumour under-dosage and normal tissue over-dosage. The findings of this study justify additional imaging between fractions in order to carry out correction.

Background and purpose To investigate critical structure movement and subsequent dose received during conformal MR-guided cervix brachytherapy. Materials and methods 21 patients (36 HDR fractions) undergoing brachytherapy for cervical cancer underwent a second MR immediately prior to treatment (pre-treatment MR). Bowel (including sigmoid), bladder and rectum were outlined on both planning and pre-treatment MR scans and dosimetry compared. Results No statistically significant differences were found between the volumes of the OAR doses across the two scans but there were large variations between patients with differences of up to 3.3Gy observed. The percentage of fractions for which D 2cc was within 10% of that planned was 61.1%, 41.7% and 47.2% for bladder, rectum and bowel, respectively. The average time between MR scans was found to be 4.75h (SD±1.2; range 3.2–9.9h), with no correlation found with critical structure movement within this range. Conclusions OAR movement is difficult to predict though significant changes occur in individual patients. In 61% of cases in our sample the D 2cc dose changed by at least 10% for at least one OAR from that planned. Pre-treatment imaging with subsequent adjustment of dosimetry will minimise the impact of organ movement on delivered dose.