Dosimetric and radiographic correlates to prostate brachytherapy‐related rectal complications

Abstract

SUMMARY Despite rates of radiation proctitis reported in the 1% to 9% range in most series, there is little information regarding rectal morbidity and dosimetric parameters. Accordingly, we have analyzed computed tomography (CT)-based dosimetric parameters based on a series of patients with endoscopically proven radiation proctitis. Nine patients diagnosed with radiation proctitis on endoscopy were identified in a prior review of 160 consecutively treated patients at the University of Washington in 1997. For each proctitis patient, two patients with no rectal bleeding matched for prostate size, isotope, and dose were selected as controls. Axial CT images obtained 2 to 4 hour postoperatively were used for postimplant dosimetry. Dose volume histograms of the rectum, surface area of the outer rectal wall receiving ≥ 100% of the prescribed dose, maximum rectal dose, and length of rectum receiving ≥ 100% prescription were obtained. Preimplant CT scans were used to group patients into three categories based on the amount of apparent rectal contact with the prostate. All rectal dosimetric parameters were statistically different between patients with or without rectal bleeding. The mean surface area receiving at least 100% prescription dose was 3.1 cm 2 for the controls vs. 6.9 cm 2 for the rectal bleeders (P = 0.001). The volume of rectum receiving at least 100% of prescription dose was 0.6 cc for the controls vs. 2.5 cc for the bleeders (P = 0.00008). Patients with full prostate-rectal contact had significantly higher rectal dose parameters compared to those with partial or no rectal contact. All nine proctitis patients were in the full-rectal-contact group compared to only seven of 18 (39%) controls. This detailed dosimetric analysis shows higher rectal doses for patients with radiation proctitis, making it a potential method of identifying patients at higher risk for receiving excessive rectal doses based on the anatomic relationship between the rectum and prostate on CT scan. Published 2001 Wiley-Liss, Inc. †

Urinary and rectal complications of contemporary permanent transperineal brachytherapy for prostate carcinoma with or without external beam radiation therapy

“…Reasons may include the nonconformal nature of the EBRT that was added, as well as other factors including inadvertent delivery of a higher dose to the rectum and placement of seeds closer than 5 mm to the rectal mucosa. 2,13,19 A distinct possibility for the higher incidence of side effects reported in the current series may be the relatively high doses of radiation delivered to both the prostate and the rectum. Although to our knowledge there is no standard for the design of implantation dosimetry plans, some authors have suggested that treatment plans should restrict the v150 to between 35-55%, and the v200 to Ͻ 20%.…”

“…16 To our knowledge, the incidence of radiation proctitis after brachytherapy in the current series is higher than in previous reports. [3][4][5][6][12][13][14][15] Moreover, the incidence of rectal symptoms for which colonoscopy was performed more than doubled after combination therapy. It is important to note that all the significant rectal complications requiring colostomy or ileostomy and colectomy were reported to occur in 4 of the 61 patients undergoing combination therapy (6.6%).…”

Devastating complications after brachytherapy in the treatment of prostate adenocarcinoma

“…Han and Wallner [18] reported that a detailed dosimetric analysis showed higher rectal doses for patients with radiation proctitis. The data on dose of radiation were not available in all of the present patients and therefore was not analysed.…”

Technical acquisition and dosimetric assessment of iodine‐125 permanent brachytherapy in localized prostate cancer: Our first series of 100 patients

“…[3][4][5][6][7][8][9][10][11][12][13] Stock et al reported that patients receiving D90 Ն 140 Gy significantly showed a lower biochemical-failure rate than those receiving D90 < 140 Gy. 4 Papagikos et al showed that V100 and D90 were independent predictors of non-biochemical recurrence after LDR-brachytherapy of the prostate.…”

“…One pathologist (KN) with expertise in prostate cancer diagnosis centrally reviewed the Gleason score of all biopsy specimens. The levels of PSA (ST AIA-PACK PSA II) were measured at 1, 3,6,12,18,24,30, and 36 months after seed implantation.…”