Rectal Displacement Research Articles

Preventing Rectal Toxicity in Prostate Cancer: Diet and Supplement Alternative to Enemas or Rectal Spacer

Background: Rectal toxicity is an important side effect of prostate cancer irradiation affecting 25% of patients. The role of dosimetric variables has a set of dose-volume constraints and curves to estimate the risk of rectal damage. The rectum position at the time of CT planning is different from the position during radiotherapy. Three methods are available to achieve optimal rectum position: enema; prostate cancer spacer; fiber-/fat-free diet. Methods: A 70.2 Gray radiation divided into 26 hypo-fractions was administered to 115 patients with prostate cancer by VMAT referred to a single center in Italy. To empty the rectum, all patients were administered a fiber-/fat-free diet and those with Eating Disorders (ED) were also added with activated charcoal (2 tablets/day) and a macrogol-based medical device (2 sachets/day). During treatment, the volumetric amount of rectum in the target was measured by comparing control-CT with simulation-CT, and acute toxicity was also checked. Results: The rectum position during control-CT in diet-only patients (29) predicted toxicity recorded during treatment, while in the ED group rectum position was adherent to position during simulations. Rectal volume target > 0.25 cc receiving a dose > V70 caused acute G3 toxicity that attenuated or worsened with rectal displacement. Acute rectal toxicity occurred in 6/29 (20.68%) patients (1 G3, 5 G1) in the diet-only group, while only in 1/86 (1.16%) patients (G1) in the ED group. No chronic toxicity was recorded in either group. Conclusion: Prostate cancer patients treated with VMAT, diet, charcoal, and macrogol emptied the rectum optimally and reduced incidence and severity of acute rectal toxicity, also with benefit on late toxicity.

Hyaluronic Acid Rectal Spacer Stability during Radiation Therapy for Localized Prostate Cancer: An Intercontinental Study.

Despite IGRT and IMRT current techniques, rectal toxicity remains a significant problem after prostate cancer radiation therapy but implanted rectal spacers have successfully reduced toxicity rates. We are reporting the results of an intercontinental prospective rectal spacer trial performed at 13 centers in Spain, Australia, and USA. Our hypothesis was that the separation created between the prostate and anterior rectal wall was stable between the time of implant and a 3-month follow-up. Our prospective multicenter study was approved by the corresponding IRBs and patients signed informed consent. It was performed between February - June 2021. Patients were imaged using T2 MRI immediately post-implant (MRI-1) and at 3 months (MRI-2). We analyzed the dimensions of hyaluronic acid (HA) rectal spacer inserted for low - intermediate risk prostate cancer treated with EBRT. The rectal displacement was determined by measuring the separation at 3 different levels: prostate midline, midgland +1cm (superior), and midgland -1 cm (inferior), from the posterior prostate capsule to the anterior rectal wall. The core laboratory performed the measurement for all sites. The confidence interval (CI) was computed using a Student's t-distribution. A total of 136 patients randomized to the Barrigel arm underwent HA rectal spacing with 100% placement success rate. There were no device failures or surgical complications. Of these, 6 were lost to follow-up. The averages of the remaining 130 patients at the 3 perirectal distances were 13.04 mm +/- 3.1 mm and 12.79 mm +/- 3.5 mm for MRI-1 and MRI-2, respectively with an average difference of -0.17 mm +/- 3.48 mm. Additional parameters are listed on the table. The results demonstrate the stability of the HA-created separation at the three different prostatic levels for up to 3 months. These findings show dimensional stability well within standard clinical margins. This indicates reliability for HA use in most clinics, as the results are relevant in the setting of dose escalation or ultra-hypofractionation schedules, as well as conventional fractionation.

Diagnostic performance of preoperative MR imaging findings for differentiation of uterine leiomyoma with intraligamentous growth from subserosal leiomyoma.

To evaluate the diagnostic performance of MRI findings for differentiating uterine leiomyoma with intraligamentous growth, or broad ligament fibroid, from subserosal leiomyoma. This study included 37 patients with surgically confirmed uterine smooth muscle tumors (36 leiomyomas and one smooth muscle tumor of uncertain malignant potential) with intraligamentous growth (IL) and size-matched control of 37 patients with subserosal leiomyoma (SS). Two radiologists independently evaluated eight preoperative MRI findings: tumor shape, degeneration, attachment to uterus, ovary elevation, ureter displacement, bladder deformation, rectal displacement, and separation of round ligament (RL) and uterine artery (UA). The diagnostic values of these findings and interobserver agreement were assessed. Receiver-operating characteristic (ROC) analysis of the number of positive MRI findings for diagnosing IL was performed. Clinical outcomes including surgical method, operation time, intraoperative blood loss, perioperative complications, and postoperative hospital stay of the two groups were compared. Significant differences in tumor shape, attachment to uterus, ovary elevation, ureter displacement, and separation of RL and UA were found between IL and SS. Four of these findings, excluding ureter displacement, showed moderate to substantial interobserver agreement. When two or more of these four findings were positive, sensitivity, specificity, and area under the ROC curve were 91%, 77%, 0.90 in reader 1 and 82%, 89%, 0.91 in reader 2. The operation time was significantly longer for IL than for SS. Tumor shape, attachment to uterus, ovary elevation, and separation of RL and UA are useful MRI findings for differentiating intraligamentous leiomyoma from subserosal leiomyoma.

Effectiveness of rectal displacement devices during prostate external-beam radiation therapy: A review.

Dose-escalated prostate radiotherapy (RT) can improve treatment outcomes, but rectal toxicity is the main limiting factor for introducing dose-escalated RT. Pushing rectal wall away from the prostate reduces the volume of the rectum in high-dose region, which can decrease both short- and long-term rectal toxicities after RT. This review focuses on the literature using different rectal displacement devices such as endorectal balloons, tissue spacers, rectal retractor, and ProSpare during prostate External beam radiotherapy, with regard to dosimetric effects, clinical benefits, prostate motion, and postoperative RT setting.

Effectiveness of rectal displacement devices in managing prostate motion: asystematic review.

To determine whether rectal displacement devices (RDDs) have aprostate-stabilizing effect during prostate external beam radiotherapy (EBRT). Asystematic literature search using the PubMed database from January1, 2000 to December30th, 2019 was conducted. The effect of RDDs on inter- and intra-fractional prostate displacements was extracted. From 356 articles identified via the PubMed database and hand search, 21articles were included in the systematic review. There was no randomized study. Twelve studies evaluated the role of the endorectal balloon (ERB) in managing prostate motion. Four studies reported the effect of hydrogel spacer on prostate motion. Four studies examined the effect of the rectal retractor (RR) on intra-fractional prostate motion, and only one study assessed the impact of ProSpare (Nottinghamshire, UK) in reducing prostate motion. Using an ERB significantly reduces intra-fractional prostate motion. This prostate-stabilizing effect of the ERB can translate into reduced planning target volume (PTV) margins and additional rectal dose sparing. Even with an ERB in place, inter-fractional prostate displacements are seen. As aconsequence, ERB application does not obviate daily verification; however, this is not acrucial topic because pretreatment imaging is always done nowadays. As compared with ERB, the hydrogel spacer significantly reduces rectal dose and toxicity without influencing prostate immobilization. The RR can increase prostate and rectal inter- and intra-fractional stability without aclear influence on the reduction of rectal toxicity. Finally, it is unclear whether ProSpare is asuitable device reducing prostate motion. Further study will be required to clarify whether the prostate-stabilizing effects of the ERB and RR can result in asafe reduction of PTV margins and further sparing of organs at risks, especially the rectum.

Rectal Motion During Intensity Modulated Radiotherapy for Post-Hysterectomy Endometrial and Cervical Cancer Patients

Intensity modulated radiotherapy (IMRT) is often used in gynecologic cancer in the post-operative setting with defined volume guidelines. It delivers a highly conformal treatment, reducing normal tissue irradiation, but results in a sharp dose gradient at the treatment volume edge. Significant vaginal cuff motion can occur due to intra- and inter-fraction motion of the rectum and bladder, which may cause inadequate target coverage. There is no consensus on how to account for the effects of rectal filling on this motion. We sought to quantify inter-fraction rectal motion during the full course of IMRT treatment and to describe if rectal motion varied by week of treatment delivery or by level within the pelvis. We retrospectively reviewed thirty consecutive patients with endometrial or cervical cancer status post hysterectomy who received IMRT to the vaginal cuff and regional lymphatics. Two reviewers measured differences in rectal position between the initial planning CT and cone-beam CT (CBCT) scans obtained daily. Department policy recommended patients be treated with full bladder daily and those with significant rectal filling asked to empty their bowels. Differences were obtained for scans obtained the first day of each week of treatment and on the final treatment date for the five weeks. At each time point, reviewers quantified anterior rectal wall movement in the anterior-posterior axis at six pre-determined levels from S4-S5 superiorly to 4 cm below the inferior border of S5 inferiorly. The resulting measurements were reviewed, and any discrepancies > 2 mm were resolved by a tertiary review. The average displacement for all patients at all timepoints and pelvic landmarks was 0.36 cm posteriorly. The maximum anterior and posterior displacements of the sample population were 3.78 cm and 4.73 cm, respectively. The average displacement did not meaningfully vary by week, measuring 0.31 cm, 0.47 cm, 0.39 cm, 0.32 cm, and 0.33 cm, all posteriorly. However, greater displacement was noticed higher in the pelvis. From superior to inferior, average displacements were 0.47 cm, 0.43 cm, 0.48 cm, 0.35 cm, 0.32 cm, and 0.18 cm, all posteriorly. 95% of all displacements fell between 2.55 cm posteriorly and 1.82 cm anteriorly. No previous studies have examined rectal displacement in the anterior-posterior axis over the course of treatment and at different levels within the pelvis for cervical and endometrial cancers. Our findings indicate significant displacement exists and that pelvic IMRT planning may benefit from anterior and posterior margins above those recommended by current guidelines. At a minimum, the results support the need for daily CBCT imaging to assess rectal filling and to develop institution guidelines for managing large displacements. In addition, margin recommendations may differ based on the level within the pelvis.

Overview of patient preparation strategies to manage internal organ motion during radiotherapy in the pelvis

AbstractIntroduction:Pelvic internal organs change in volume and position during radiotherapy. This may compromise the efficacy of treatment or worsen its toxicity. There may be limitations to fully correcting these changes using online image guidance; therefore, effective and consistent patient preparation and positioning remain important. This review aims to provide an overview of the extent of pelvic organ motion and strategies to manage this motion.Methods and Materials:Given the breadth of this topic, a systematic review was not undertaken. Instead, existing systematic reviews and individual high-quality studies addressing strategies to manage pelvic organ motion have been discussed. Suggested levels of evidence and grades of recommendation for each strategy have been applied.Results:Various strategies to manage rectal changes have been investigated including diet and laxatives, enemas and rectal emptying tubes and rectal displacement with endorectal balloons (ERBs) and rectal spacers. Bladder-filling protocols and bladder ultrasound have been used to try to standardise bladder volume. Positioning the patient supine, using a full bladder and positioning prone with or without a belly board, has been examined in an attempt to reduce the volume of irradiated small bowel. Some randomised trials have been performed, with evidence to support the use of ERBs, rectal spacers, bladder-filling protocols and the supine over prone position in prostate radiotherapy. However, there was a lack of consistent high-quality evidence that would be applicable to different disease sites within the pelvis. Many studies included small numbers of patients were non-randomised, used less conformal radiotherapy techniques or did not report clinical outcomes such as toxicity.Conclusions:There is uncertainty as to the clinical benefit of many of the commonly adopted interventions to minimise pelvic organ motion. Given this and the limitations in online image guidance compensation, further investigation of adaptive radiotherapy strategies is required.

Phase 2 Multicenter Study of Gantry-Based Stereotactic Radiotherapy Boost for Intermediate and High Risk Prostate Cancer (PROMETHEUS).

Objectives: To report feasibility, early toxicity, and PSA kinetics following gantry-based, stereotactic radiotherapy (SBRT) boost within a prospective, phase 2, multicenter study (PROMETHEUS: ACTRN12615000223538).Methods: Patients were treated with gantry-based SBRT, 19–20 Gy in two fractions delivered 1 week apart, followed by conventionally fractionated IMRT (46 Gy in 23 fractions). The study mandated MRI fusion for RT planning, rectal displacement, and intrafraction image guidance. Toxicity was prospectively graded using the Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4).Results: Between March 2014 and July 2018, 135 patients (76% intermediate, 24% high-risk) with a median age of 70 years (range 53–81) were treated across five centers. Short course (≤6 months) androgen deprivation therapy (ADT) was used in 36% and long course in 18%. Rectal displacement method was SpaceOAR in 59% and Rectafix in 41%. Forty-two and ninety-three patients were treated at the 19 Gy and 20 Gy dose levels, respectively. Median follow-up was 24 months. Acute grade 2 gastrointestinal (GI) and urinary toxicity occurred in 4.4 and 26.6% with no acute grade 3 toxicity. At 6, 12, 18, 24, and 36 months post-treatment the prevalence of late grade ≥2 gastrointestinal toxicity was 1.6, 3.7, 2.2, 0, and 0%, respectively, and the prevalence of late grade ≥2 urinary toxicity was 0.8, 11, 12, 7.1, and 6.3%, respectively. Three patients experienced grade 3 late toxicity at 12 to 18 months which subsequently resolved to grade 2 or less. For patients not receiving ADT the median PSA value pre-treatment was 7.6 ug/L (1.1–20) and at 12, 24, and 36 months post-treatment was 0.86, 0.36, and 0.20 ug/L.Conclusions: Delivery of a gantry-based SBRT boost is feasible in a multicenter setting, is well-tolerated with low rates of early toxicity and is associated with promising PSA responses. A second transient peak in urinary toxicity was observed at 18 months which subsequently resolved. Follow-up is ongoing to document late toxicity, long-term patient reported outcomes, and tumor control with this approach.

Rectal wall delineation in patients with a rectal displacement device in place during prostate cancer radiotherapy

Rectal wall delineation in patients with a rectal displacement device in place during prostate cancer radiotherapy

The effect of Rectal Retractor, a rectal protector on rectal dose in radical prostate radiotherapy

Introduction: The close proximity of the rectum tissue to the prostate gland results in rectal toxicity during prostate radiotherapy. Rectal Retractor (RR) is a rectal displacement technique that inserts into the rectum, as a result, the lateral and dorsal part of the rectal wall push away from high dose areas. The aim of this study was to investigate the dosimetric consequences and rectal tissue sparing effect of RR during prostate three-dimensional radiotherapy (3DCRT). Materials and Methods: In 15 patients with localized prostate cancer, two planning CT- scans were carried out: without and with RR. The prostate and seminal vesicles plus 5 mm margin were considered as planning target volume (PTV). All patients were treated using 3DCRT with prescription dose of 80 Gy. The inter-fraction setup errors were corrected by electronic portal imaging device (EPID) and fiducial gold markers. Dose volume histograms of the rectum were compared in plan without and with RR. Results: All patients well tolerated RR during first 20-25 fractions. Using RR, mean dose to the rectum was 39 cGy (P <0.001) lower per fraction. Comparison between plan without and with RR indicated that RR resulted in a mean reduction of 57.3%, 63.8%, 71.9% and 72.8% in rectal V50Gy, V60Gy, V70Gy and V75Gy, respectively (P <0.001). Conclusion: The retraction of the rectum is associated with a significant lower dose to the rectum. This may lead to reduction of the rectal toxicity during prostate radiotherapy.

Does setup on rectal wall improve rectal cancer boost radiotherapy?

BackgroundRectal cancer patients that show a pathological complete response (pCR) after neo-adjuvant chemo-radiotherapy, have better prognosis. To increase pCR rates several studies escalate the tumor irradiation dose. However, due to lacking tumor contrast on online imaging techniques, no direct tumor setup can be performed and large boost margins are needed to ensure tumor coverage.The purpose of this study was to evaluate the feasibility of performing a setup on rectal wall for rectal cancer boost radiotherapy, thereby using rectal wall nearby the tumor as tumor position surrogate.MethodsFor sixteen patients, daily MRI’s were performed during 1 week of radiotherapy. On each of these images, tumor and rectum were delineated. Residual displacements were determined per surface voxel after setup on bony anatomy or nearby rectal wall and setup errors for both setups were compared. Furthermore for every rectal wall voxel nearby the tumor, displacement was compared with the closest tumor point and correlation was determined.ResultsMean (SD) setup error was 2.7 mm (3.3 mm) and 2.2 mm (3.2 mm) after setup on bony anatomy and rectal wall respectively. Nevertheless, similar PTV-margin estimates i.e. 95th percentile distances, were found; 8.0 mm. Also, a merely moderate correlation; ρ = 0.66 was found between rectal wall and tumor displacement. Further investigation into tumor and rectal mobility differences showed that the rectal wall lacks appropriate anatomical landmarks to find true displacements, especially to capture motion along the rectal wall.ConclusionsSetup on rectal wall slightly reduces mean setup errors but requires a similar PTV-margin as compared to setup on bony anatomy. Rectal mobility might be similar to tumor mobility, but due the absence of anatomical landmarks in the rectum, displacements along the rectal wall are not detected on current online imaging. Therefore, to further reduce tumor position uncertainties, direct or indirect online tumor visualization is needed.

Interfractional Rectal Displacement Requiring Repeated Precaution Did Not Correlate to Biochemical Control and Rectal Toxicity in Patients with Prostate Cancer Treated with Image-guided Intensity-modulated Radiation Therapy

To investigate the correlation between frequency of action level of interfractional rectal displacement requiring repeated precaution in patients with prostate cancer and late toxicity from image-guided intensity-modulated radiation therapy (IG-IMRT) using helical tomotherapy. We examined 264 patients who underwent IG-IMRT during 2007-2011. Megavoltage computed tomographic (MVCT) images were acquired before radiation therapy and was examined with soft-tissue matching by comparing treatment planning images within 9,345 fractions. Displacement of the anterior rectal region larger than 5 mm, requiring repeated precaution, was defined as the level of rectal displacement requiring action (ARD). ARD was identified in 815 (7.7%) out of 9,345 fractions and at least once in 82% (216/264) of patients. The highest incidence of ARD (11%) was found during the initial week of treatment (first five and next five fractions), after which the incidence decreased to 6% (p<0.0001). Patients with lean body (lower body mass index (BMI) tended to have a higher incidence of ARD. We identified 16 (6%) cases of gastrointestinal toxicity and 12 (4.5%) genitourinary toxicities as a late adverse reaction (3 months or later after IG-IMRT). There was no correlation between ARD and late toxicity. Prostate-specific antigen (PSA) control was also similar (p=0.12) between those with ARD (96% at 5 year) and those without ARD (88%). ARD occurred predominantly in lean patients, during the initial week of treatment and became less likely over time. ARD was not correlated to late toxicity and PSA control, therefore, IG-IMRT technique was able to adequately control error due to interfractional prostate and rectal motion.

Real-time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement.

BackgroundKilovoltage Intrafraction Monitoring (KIM) is a method which determines the three‐dimensional position of the prostate from two‐dimensional kilovoltage (kV) projections taken during linac based radiotherapy treatment with real‐time feedback. Rectal displacement devices (RDDs) allow for improved rectal dosimetry during prostate cancer treatment. This study used KIM to perform a preliminary investigation of prostate intrafraction motion observed in patients with an RDD in place.MethodsTen patients with intermediate to high‐risk prostate cancer were treated with a Rectafix RDD in place during two boost fractions of 9.5–10 Gy delivered using volumetric modulated arc therapy (VMAT) on Clinac iX and Truebeam linacs. Two‐dimensional kV projections were acquired during treatment. KIM software was used following treatment to determine the displacement of the prostate over time. The displacement results were analyzed to determine the percentage of treatment time the prostate spent within 1 mm, between 1 and 2 mm, between 2 and 3 mm and greater than 3 mm from its initial position.Results KIM successfully measured displacement for 19 prostate stereotactic boost fractions. The prostate was within 1 mm of its initial position for 84.8%, 1–2 mm for 14%, 2–3 mm 1.2% and ≥3 mm only 0.4% of the treatment time.ConclusionsIn this preliminary study using KIM, KIM was successfully used to measure prostate intrafraction motion, which was found to be small in the presence of a rectal displacement device.Trial registrationThe Hunter New England Human Research Ethics Committee reference number is 14/08/20/3.01.

Real-time in vivo rectal wall dosimetry using MOSkin detectors during linac based stereotactic radiotherapy with rectal displacement

BackgroundMOSFET dosimetry is a method that has been used to measure in-vivo doses during brachytherapy treatments and during linac based radiotherapy treatment. Rectal displacement devices (RDDs) allow for safe dose escalation for prostate cancer treatment. This study used dual MOSkin detectors to assess real-time in vivo rectal wall dose in patients with an RDD in place during a high dose prostate stereotactic body radiation therapy (SBRT) boost trial.MethodsThe PROMETHEUS study commenced in 2014 and provides a prostate SBRT boost dose with a RDD in place. Twelve patients received two boost fractions of 9.5–10 Gy each delivered to the prostate with a dual arc volumetric modulated arc therapy (VMAT) technique. Two MOSkins in a face-to-face arrangement (dual MOSkin) were used to decrease angular dependence. A dual MOSkin was attached to the anterior surface of the Rectafix and read out at 1 Hz during each treatment. The planned dose at each measurement point was exported from the planning system and compared with the measured dose. The root mean square error normalised to the total planned dose was calculated for each measurement point and treatment arc for the entire course of treatment.ResultsThe average difference between the measured and planned doses over the whole course of treatment for all arcs measured was 9.7% with a standard deviation of 3.6%. The cumulative MOSkin reading was lower than the total planned dose for 64% of the arcs measured. The average difference between the final measured and final planned doses for all arcs measured was 3.4% of the final planned dose, with a standard deviation of 10.3%.ConclusionsMOSkin detectors were an effective tool for measuring dose delivered to the anterior rectal wall in real time during prostate SBRT boost treatments for the purpose of both ensuring the rectal doses remain within acceptable limits during the treatment and for the verification of final rectal doses.

Is There a Role for Perirectal Spacing with Hydrogel Spacers in Gynecologic Brachytherapy? A Dosimetric Study of Rectal Dose Reduction with Simulated Posterior Rectal Displacement

Is There a Role for Perirectal Spacing with Hydrogel Spacers in Gynecologic Brachytherapy? A Dosimetric Study of Rectal Dose Reduction with Simulated Posterior Rectal Displacement

1260 poster THE INFLUENCE OF RECTAL FILLING ON RECTAL DISPLACEMENT AND ITS IMPACT ON DOSIMETRY WITHIN THE PTV

1260 poster THE INFLUENCE OF RECTAL FILLING ON RECTAL DISPLACEMENT AND ITS IMPACT ON DOSIMETRY WITHIN THE PTV

Rectal Deformation and Displacement during Pre-operative Radiotherapy for Rectal Cancer: Insights from Mid-treatment Cone-beam Computed Tomography

Rectal Deformation and Displacement during Pre-operative Radiotherapy for Rectal Cancer: Insights from Mid-treatment Cone-beam Computed Tomography

Analysis of retroperitoneal tumors operated on in a gynecology clinic

To evaluate the patients with retroperitoneal tumors that presented as pelvic mass and were operated on in our gynecology clinic. Records of 16 patients were analyzed retrospectively. All patients had a palpable mass on physical examination and abdominal pain was the most frequent symptom. The median diameter of the tumors was 15 cm. The postoperative histopathology of the patients was leiomyosarcoma in nine, retroperitoneal fibrosis in three, and paraganglioma, hamartoma, and dermoid cyst in three patients. All the tumors were excised almost completely. The incorrect preoperative diagnosis of the patients in this study is due to the presentation of the patients with non-specific symptoms and not considering the less common differential diagnosis of a pelvic mass. For clinical signs of vascular or rectal displacement, or where there is evidence of ureteric obstruction, retroperitoneal pathology should be kept in mind.

Rectal dose sparing with a balloon catheter and ultrasound localization in conformal radiation therapy for prostate cancer.

To compare the rectal wall and bladder volume in the high dose region with or without the use of a balloon catheter with both three-dimensional (3D)-conformal and intensity modulated radiation therapy (CRT, IMRT) approaches in the treatment of prostate cancer. Five patients with a wide range of prostate volumes and treated with primary external beam radiation therapy for localized prostate cancer were selected for analysis. Pinnacle treatment plans were generated utilizing a 3D conformal six-field design and an IMRT seven coplanar-field plan with a novel, three-step optimization and with ultrasound localization. Separate plans were devised with a rectal balloon deflated or air inflated with and without inclusion of the seminal vesicles (SV) in the target volume. The prescription dose was 76Gy in 38 fractions of 2Gy each. Cumulative dose-volume histograms (DVHs) were analyzed for the planning target volume (PTV), rectal wall, and bladder with an inflated (60cc air) or deflated balloon with and without SV included. The volumes of rectal wall and bladder above 60, 65, and 70Gy with each treatment approach were evaluated. Daily balloon placement was well-tolerated with good patient positional reproducibility. Inflation of the rectal balloon in all cases resulted in a significant decrease in the absolute volume of rectal wall receiving greater than 60, 65, or 70Gy. The rectal sparing ratio (RSR), consisting of a structure's high dose volume with the catheter inflated, divided by the volume with the catheter deflated, was calculated for each patient with and without seminal vesicle inclusion for 3D-CRT and IMRT. For 3D-CRT, RSRs with SV included were 0.59, 0.59, and 0.56 and with SV excluded were 0.60, 0.58, and 0.54 at doses of greater than 60, 65, and 70Gy, respectively. Similarly, for IMRT, the mean RSRs were 0.59, 0.59, and 0.63 including SV and 0.71, 0.66, and 0.67 excluding SV at these same dose levels, respectively. Averaged over all conditions, inflation of the rectal balloon resulted in a significant reduction in rectal volume receiving > or =65Gy to a mean ratio of 0.61 (P=0.01) or, in other words, a mean fractional high dose rectal sparing of 39%. There was a slight overall increase to 1.13 in the relative volume of bladder receiving at least 65Gy; however, this was not significant (P=0.6). Use of an endorectal balloon with a non-image-guided 3D-CRT plan produced about as much rectal dose sparing as a highly conformal, image-guided IMRT approach without a balloon. However, inclusion of a balloon with IMRT produced further rectal sparing still. These results indicate that use of a rectal balloon with a 3D-CRT plan incorporating typical treatment margins will produce significant high dose rectal sparing that is comparable to that achieved by a highly conformal IMRT with ultrasound localization. Further sparing is achieved with the inclusion of a balloon catheter in an IMRT plan. Thus, in addition to a previously reported advantage of prostate immobilization, the use of a rectal displacement balloon during daily treatment results in high dose rectal wall sparing during both modestly and highly conformal radiotherapy. Such sparing could assist in controlling and limiting rectal toxicity during increasingly aggressive dose escalation.

Retroperitoneal sarcoma: time for a change in attitude?

Retroperitoneal sarcoma (RPS) is considered a disease with poor prognosis partly because of the difficulty with diagnosis at an early stage. This review assesses the current best practice principles for RPS and finds evidence suggesting a better outlook for appropriately managed cases. Recommendations are made for improving diagnostic certainty before laparotomy and inappropriate transperitoneal biopsy occur. A critical review of the English language literature was conducted using MEDLINE software and searching the terms 'retroperitoneal sarcoma' alone or in combination with 'prognosis', 'surgery' and 'adjuvant therapy'. Retroperitoneal sarcoma is a rare disease but when appropriately managed the disease-free survival can be improved and may even approach that of extremity soft tissue sarcoma. One of the greatest barriers to improving outcome is the misinterpretation of clinical signs and an over-reliance on ultrasound diagnosis in pelvic presentations, or misinterpretation of clinical signs and/or computer tomography (CT) scans in abdominal masses. Physicians referring patients with a retroperitoneal mass should consider more frequently the less common differential diagnoses of an abdominopelvic mass including retroperitoneal sarcoma. This is especially true in circumstances where there is a circumscribed, predominantly solid tumour, with clinical or radiological signs of vascular or rectal displacement, ureteric obstruction and/or classic renal rotational displacement. The more frequent use of CT scans with intravenous and oral contrast with referral prior to inappropriate transperitoneal biopsy is recommended. In atypical cases where preoperative biopsy is necessary, extraperitoneal routes are preferable. Complete en bloc surgical excision at the first laparotomy is the treatment of choice in RPS. Macroscopic clearance may necessitate resection of adjacent viscera, neurovascular structures or abdominopelvic walls but, if achieved, may lead to long-term survival depending on individual tumour biology.