Blog
About

19
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Effect of constipation on dosimetry after permanent seed brachytherapy for prostate cancer

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Purpose

          A major concern in prostate brachytherapy is rectal toxicity, which mainly depends on the dose and volume of rectum involved by radiation. We hypothesize that the rectal distension, as produced by constipation, influences the dosimetric parameters of the rectum and other pelvic organs.

          Material and methods

          An open, controlled, prospective, paired trial (pre-post test) was designed and conducted. Twenty-three patients treated with prostate brachytherapy were recruited, of which 21 were evaluated. All of them underwent two CT scans, the first one with empty rectum and the second with rectum distended by a catheter balloon. Target volumes and organs at risk were delineated, and dosimetric parameters were calculated and then compared for each patient between both CT.

          Results

          For rectum, D 2cc increased 15.8% ( p < 0.001) and D 0.1cc 24.05% ( p = 0.002) when the rectum was full. A significant difference was also found in dose distribution to prostate, when rectum is distended, a 1% decrease in V 100 ( p = 0.031) and a 3.25% in D 90 ( p = 0.033) was registered.

          Conclusions

          The status of rectal distension, as occurs in constipation, has a deleterious influence on prostate brachytherapy dosimetry. This situation increases the radiation to rectum and modifies dose distribution to prostate. We recommend prevention of constipation for at least two half lives of the radioactive seeds.

          Related collections

          Most cited references 17

          • Record: found
          • Abstract: found
          • Article: not found

          Increased risk of biochemical and local failure in patients with distended rectum on the planning CT for prostate cancer radiotherapy.

          To retrospectively test the hypothesis that rectal distension on the planning computed tomography (CT) scan is associated with an increased risk of biochemical and local failure among patients irradiated for prostate carcinoma when a daily repositioning technique based on direct prostate-organ localization is not used. This study included 127 patients who received definitive three-dimensional conformal radiotherapy for prostate cancer to a total dose of 78 Gy at The University of Texas M. D. Anderson Cancer Center. Rectal distension was assessed by calculation of the average cross-sectional rectal area (CSA; defined as the rectal volume divided by length) and measuring three rectal diameters on the planning CT. The impact of rectal distension on biochemical control, 2-year prostate biopsy results, and incidence of Grade 2 or greater late rectal bleeding was assessed. The incidence of biochemical failure was significantly higher among patients with distended rectums (CSA >11.2 cm(2)) on the planning CT scan (p = 0.0009, log-rank test). Multivariate analysis indicates that rectal distension and high-risk disease are independent risk factors for biochemical failure, with hazard ratios of 3.89 (95% C.I. 1.58 to 9.56, p = 0.003) and 2.45 (95% C.I. 1.18 to 5.08, p = 0.016), respectively. The probability of residual tumor without evidence of radiation treatment (as scored by the pathologist) increased significantly with rectal distension (p = 0.010, logistic analysis), and a lower incidence of Grade 2 or greater late rectal bleeding within 2 years was simultaneously observed with higher CSA values (p = 0.031, logistic analysis). We found strong evidence that rectal distension on the treatment-planning CT scan decreased the probability of biochemical control, local control, and rectal toxicity in patients who were treated without daily image-guided prostate localization, presumably because of geographic misses. Therefore, an empty rectum is warranted at the time of simulation. These results also emphasize the need for image-guided radiotherapy to improve local control in irradiating prostate cancer.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Late rectal toxicity: dose-volume effects of conformal radiotherapy for prostate cancer.

            To identify dosimetric, anatomic, and clinical factors that correlate with late rectal toxicity after three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. We retrospectively analyzed the dose-volume histograms and clinical records of 163 Stage T1b-T3c prostate cancer patients treated between 1992 and 1999 with 3D-CRT, to a total isocenter dose of 74-78 Gy at The University of Texas M. D. Anderson Cancer Center. The median follow-up was 62 months (range 24-102). All late rectal complications were scored using modified Radiation Therapy Oncology Group and Late Effects Normal Tissue Task Force criteria. The 6-year toxicity rate was assessed using Kaplan-Meier analysis and the log-rank test. A univariate proportional hazards regression model was used to test the correlation between Grade 2 or higher toxicity and the dosimetric, anatomic, and clinical factors. In a multivariate regression model, clinical factors were added to the dosimetric and anatomic variables to determine whether they significantly altered the risk of developing late toxicity. At 6 years, the rate of developing Grade 2 or higher late rectal toxicity was 25%. A significant volume effect was observed at rectal doses of 60, 70, 75.6, and 78 Gy, and the risk of developing rectal complications increased exponentially as greater volumes were irradiated. Although the percentage of rectal volume treated correlated significantly with the incidence of rectal complications at all dose levels (p <0.0001 for all comparisons), the absolute rectal volume appeared to be a factor only at the higher doses of 70, 75.6, and 78 Gy (p = 0.0514, 0.0016, and 0.0021, respectively). The following variables also correlated with toxicity on the univariate analysis: maximal dose to the clinical target volume, maximal dose to rectum, maximal dose to the rectum as a percentage of the prescribed dose, and maximal dose delivered to 10 cm(3) of the rectum. Of the clinical variables tested, only a history of hemorrhoids correlated with rectal toxicity (p = 0.003). Multivariate analysis showed that the addition of hemorrhoids increased the risk of toxicity for each dosimetric variable found to be significant on univariate analysis (p <0.05 for all comparisons). Dose-volume histogram analyses clearly indicated a volume effect on the probability of developing late rectal complications. Therefore, dose escalation may be safely achieved by adherence to dose-volume histogram constraints during treatment planning and organ localization at the time of treatment to ensure consistent patient setup.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Conformal arc radiotherapy for prostate cancer: increased biochemical failure in patients with distended rectum on the planning computed tomogram despite image guidance by implanted markers.

              To evaluate the effect of rectal distention on the planning computed tomogram on freedom from biochemical failure (FFBF) of prostate cancer patients treated with image-guided conformal arc radiotherapy. The outcomes of 238 patients with T1-T3N0M0 tumors were analyzed, with a median follow-up of 53 months (range, 24-93 months). In 213 patients, daily co-registration of X-rays and digitally reconstructed radiographs was used for positioning, whereas in 25 patients positioning was done using direct prostate visualization with implanted markers. The rectal average cross-sectional area was determined on the planning computed tomogram. The 5-year freedom from Grade 3 to 4 late gastrointestinal and urinary side effect, according to the Radiation Therapy Oncology Group criteria, was 100% and 99.4% respectively. The 5-year FFBF was 88.4%. On multivariate analysis the following variables were significantly related to worse FFBF: risk group according to the National Comprehensive Cancer Network (high- to very high risk vs. intermediate- to low-risk), dose (70 vs. 78 Gy), average cross-sectional area (> or =16 vs. <16 cm(2)) and, unexpectedly, the use of implanted markers as opposed to bony structures for patient positioning. In retrospect, the margins around the clinical target volume appeared to be inadequate in the cases in which markers were used. Overall, the outcome of patients treated with image-guided conformal arc radiotherapy is excellent. We were able to confirm the negative prognostic impact of a distended rectum on the planning computed tomogram described by others. The study illustrates the potential danger of image guidance techniques as to margin reduction around the clinical target volume.
                Bookmark

                Author and article information

                Journal
                J Contemp Brachytherapy
                J Contemp Brachytherapy
                JCB
                Journal of Contemporary Brachytherapy
                Termedia Publishing House
                1689-832X
                2081-2841
                18 August 2015
                August 2015
                : 7
                : 4
                : 247-251
                Affiliations
                [1 ]Radiation Oncology Department, Hospital Universitario de Canarias
                [2 ]Department of Physical Medicine and Pharmacology, La Laguna University
                [3 ]Medical Physics Department, Hospital Universitario de Canarias, Canary Islands, Spain
                Author notes
                Address for correspondence: L. Fernando Otón, MD, PhD, Servicio de Oncología Radioterápica, Hospital Universitario de Canarias, Ofra s/n. 38320 La Laguna, Santa Cruz de Tenerife, Spain. phones: +34 922678951, +34 620690845. e-mail: lfoton@ 123456ull.es
                Article
                25618
                10.5114/jcb.2015.53491
                4643726
                Copyright © 2015 Termedia Sp. z o. o.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.

                Categories
                Original Paper

                Oncology & Radiotherapy

                seeds, constipation, ldr, prostate cancer, rectal toxicity, brachytherapy

                Comments

                Comment on this article

                Similar content 939

                Cited by 3

                Most referenced authors 126