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

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Abstract

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.

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Most cited references 17

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

Adrienne D. Cox, R Crevoisier, Radhe Mohan … (2005)

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.

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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.

Benedikt Engels, Guy Soete, D. Verellen … (2009)

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.

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Evaluating the effect of rectal distension and rectal movement on prostate gland position using cine MRI.

D Dearnaley, V Khoo, Colin J. Suckling … (1999)

To evaluate the dynamic interrelationship between rectal distension and rectal movements, and to determine the effect of rectal movement on the position of the prostatic gland using cine magnetic resonance imaging (MRI). Fifty-five patients with biopsy-proven or suspected prostate cancer were examined in the axial plane using repeated spoiled gradient-echo sequences every 10 seconds for 7 minutes. Twenty-four patients received bowel relaxants before imaging. Images were analyzed for the degree of rectal distension, for the incidence, magnitude, and number of rectal and prostate movements. Rectal movements were seen in 28 (51%) patients overall, in 10 (42%) of those receiving bowel relaxants and in 18 (58%) not receiving bowel relaxants. The incidence of rectal movements correlated with the degree of rectal distension (p = 0.0005), but the magnitude of rectal movements did not correlate with the degree of rectal distension. Eighty-six rectal movements resulting in 33 anterior-posterior (AP) prostate movements were seen. The magnitude of rectal movements correlated well with degree of prostate movements (p < 0.001). Prostate movements in the AP direction were seen in 16 (29%) patients, and in 9 (16%) patients the movement was greater than 5 mm. The median prostate AP displacement was anterior by 4.2 (-5 to +14 mm). Cine MRI is able to demonstrate near real time rectal and associated prostate movements. Rectal movements are related to rectal distension and result in significant displacements of the prostate gland over a time period similar to that used for daily fractionated radiotherapy treatments. Delivery of radiotherapy needs to take into account these organ movements.

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Author and article information

Journal

Journal ID (iso-abbrev): J Contemp Brachytherapy

Title: Journal of contemporary brachytherapy

Publisher: Termedia Sp. z.o.o.

ISSN: 1689-832X

ISSN (Print): 2081-2841

Publication date (Electronic): Aug 2015

Volume: 7

Issue: 4

Affiliations

[1 ] Radiation Oncology Department, Hospital Universitario de Canarias ; Department of Physical Medicine and Pharmacology, La Laguna University.

[2 ] Radiation Oncology Department, Hospital Universitario de Canarias.

[3 ] Medical Physics Department, Hospital Universitario de Canarias, Canary Islands, Spain.

Article

Publisher Item ID: 25618

DOI: 10.5114/jcb.2015.53491

PMC ID: 4643726

PubMed ID: 26622226

SO-VID: ad765eb1-ee4d-43de-8cd4-0015adbe4467

History

Keywords: LDR,brachytherapy,constipation,prostate cancer,rectal toxicity,seeds

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Keywords: LDR, brachytherapy, constipation, prostate cancer, rectal toxicity, seeds

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

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Abstract

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Cancer Metabolism

Most cited references 17

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

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.

Evaluating the effect of rectal distension and rectal movement on prostate gland position using cine MRI.

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