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Kishi K, Sato M, Shirai S, Sonomura T, Yamama R. Reirradiation of prostate cancer with rectum preservation: eradicative high-dose-rate brachytherapy with natural type hyaluronate injection. Brachytherapy 2011; 11:144-8. [PMID: 21820975 DOI: 10.1016/j.brachy.2011.06.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 05/05/2011] [Accepted: 06/28/2011] [Indexed: 10/17/2022]
Abstract
INTRODUCTION Reirradiation of locally recurrent prostate cancer after radiotherapy is limited because of its toxicity to the rectum that is closely adjacent to the prostate. To solve geometric anatomic constraints, including rectal size and distance from the prostate, we developed a technique that modifies the geometry by noninvasive direct intervention. METHODS AND MATERIALS In a patient with local recurrence of prostate cancer at 18 months after initial radiotherapy of 61.8 GyE(LQ2,3) (gray equivalent in 2 Gy/fraction at α/β=3 calculated with linear quadratic [LQ] model) to the prostate, we prescribed 16 Gy (60.8 GyE(LQ2,3) or 78.2 GyE(LQ2,1.6)) of reirradiation by high-dose-rate brachytherapy, using a bolus injection of native-type hyaluronate to create and maintain a distance between the prostate and the rectum and decrease rectal size during treatment. RESULTS The procedure was achieved in 10min, without complications. Rectal D(2cc) of the reirradiation was 5.58 Gy (9.58 GyE(LQ2,3)). Compared with the initial radiation, the gel injection resulted in an improved therapeutic ratio. The patient was regularly followed up at our clinic; at over 3.5 years after reirradiation, there was no evidence of recurrence or radiation-related toxicities greater than Grade 2, maintaining a nadir prostate-specific antigen level of 0.03 ng/mL without hormonal therapy. CONCLUSION We consider that this technique is useful for achieving safe and curative reirradiation of prostate cancer.
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Affiliation(s)
- Kazushi Kishi
- Department of Radiation Oncology, Tumor Center, Wakayama Medical University Hospital, Wakayama City, Wakayama, Japan.
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Housri N, Ning H, Ondos J, Choyke P, Camphausen K, Citrin D, Arora B, Shankavaram U, Kaushal A. Parameters favorable to intraprostatic radiation dose escalation in men with localized prostate cancer. Int J Radiat Oncol Biol Phys 2011; 80:614-20. [PMID: 20932672 PMCID: PMC3580994 DOI: 10.1016/j.ijrobp.2010.06.050] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2010] [Revised: 05/15/2010] [Accepted: 06/29/2010] [Indexed: 11/26/2022]
Abstract
PURPOSE To identify , within the framework of a current Phase I trial, whether factors related to intraprostatic cancer lesions (IPLs) or individual patients predict the feasibility of high-dose intraprostatic irradiation. METHODS AND MATERIALS Endorectal coil MRI scans of the prostate from 42 men were evaluated for dominant IPLs. The IPLs, prostate, and critical normal tissues were contoured. Intensity-modulated radiotherapy plans were generated with the goal of delivering 75.6 Gy in 1.8-Gy fractions to the prostate, with IPLs receiving a simultaneous integrated boost of 3.6 Gy per fraction to a total dose of 151.2 Gy, 200% of the prescribed dose and the highest dose cohort in our trial. Rectal and bladder dose constraints were consistent with those outlined in current Radiation Therapy Oncology Group protocols. RESULTS Dominant IPLs were identified in 24 patients (57.1%). Simultaneous integrated boosts (SIB) to 200% of the prescribed dose were achieved in 12 of the 24 patients without violating dose constraints. Both the distance between the IPL and rectum and the hip-to-hip patient width on planning CT scans were associated with the feasibility to plan an SIB (p = 0.002 and p = 0.0137, respectively). CONCLUSIONS On the basis of this small cohort, the distance between an intraprostatic lesion and the rectum most strongly predicted the ability to plan high-dose radiation to a dominant intraprostatic lesion. High-dose SIB planning seems possible for select intraprostatic lesions.
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Affiliation(s)
- Nadine Housri
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Holly Ning
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - John Ondos
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Peter Choyke
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Kevin Camphausen
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Deborah Citrin
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Barbara Arora
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Uma Shankavaram
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Aradhana Kaushal
- Radiation Oncology Branch Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
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Human collagen injections to reduce rectal dose during radiotherapy. Int J Radiat Oncol Biol Phys 2011; 82:1918-22. [PMID: 21514738 DOI: 10.1016/j.ijrobp.2011.02.034] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 02/07/2011] [Accepted: 02/17/2011] [Indexed: 12/13/2022]
Abstract
OBJECTIVES The continuing search for interventions, which address the incidence and grade of rectal toxicities associated with radiation treatment of prostate cancer, is a major concern. We are reporting an investigational trial using human collagen to increase the distance between the prostate and anterior rectal wall, thereby decreasing the radiation dose to the rectum. METHODS This is a pilot study evaluating the use of human collagen as a displacing agent for the rectal wall injected before starting a course of intensity-modulated radiotherapy (IMRT) for prostate cancer. Using a transperineal approach, 20 mL of human collagen was injected into the perirectal space in an outpatient setting. Computerized IMRT plans were performed pre- and postcollagen injection, and after a patient completed their radiotherapy, to determine radiation dose reduction to the rectum associated with the collagen injection. Computed tomography scans were performed 6 months and 12 months after completing their radiotherapy to evaluate absorption rate of the collagen. All patients were treated with IMRT to a dose of 75.6 Gy to the prostate. RESULTS Eleven patients were enrolled into the study. The injection of human collagen in the outpatient setting was well tolerated. The mean separation between the prostate and anterior rectum was 12.7 mm. The mean reduction in dose to the anterior rectal wall was 50%. All men denied any rectal symptoms during the study. CONCLUSIONS The transperineal injection of human collagen for the purpose of tissue displacement is well tolerated in the outpatient setting. The increased separation between the prostate and rectum resulted in a significant decrease in radiation dose to the rectum while receiving IMRT and was associated with no rectal toxicities.
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Kopp RW, Duff M, Catalfamo F, Shah D, Rajecki M, Ahmad K. VMAT vs. 7-field-IMRT: assessing the dosimetric parameters of prostate cancer treatment with a 292-patient sample. Med Dosim 2011; 36:365-72. [PMID: 21377863 DOI: 10.1016/j.meddos.2010.09.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 09/03/2010] [Accepted: 09/09/2010] [Indexed: 11/25/2022]
Abstract
We compared normal tissue radiation dose for the treatment of prostate cancer using 2 different radiation therapy delivery methods: volumetric modulated arc therapy (VMAT) vs. fixed-field intensity-modulated radiation therapy (IMRT). Radiotherapy plans for 292 prostate cancer patients treated with VMAT to a total dose of 7740 cGy were analyzed retrospectively. Fixed-angle, 7-field IMRT plans were created using the same computed tomography datasets and contours. Radiation doses to the planning target volume (PTV) and organs at risk (bladder, rectum, penile bulb, and femoral heads) were measured, means were calculated for both treatment methods, and dose-volume comparisons were made with 2-tailed, paired t-tests. The mean dose to the bladder was lower with VMAT at all measured volumes: 5, 10, 15, 25, 35, and 50% (p < 0.05). The mean doses to 5 and 10% of the rectum, the high-dose regions, were lower with VMAT (p < 0.05). The mean dose to 15% of the rectal volume was not significantly different (p = 0.95). VMAT exposed larger rectal volumes (25, 35, and 50%) to more radiation than fixed-field IMRT (p < 0.05). Average mean dose to the penile bulb (p < 0.05) and mean dose to 10% of the femoral heads (p < 0.05) were lower with VMAT. VMAT therapy for prostate cancer has dosimetric advantages for critical structures, notably for high-dose regions compared with fixed-field IMRT, without compromising PTV coverage. This may translate into reduced acute and chronic toxicity.
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Affiliation(s)
- Robert W Kopp
- SUNY Upstate Medical University, College of Medicine, Syracuse, NY, USA
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Pederson AW, Fricano J, Correa D, Pelizzari CA, Liauw SL. Late toxicity after intensity-modulated radiation therapy for localized prostate cancer: an exploration of dose-volume histogram parameters to limit genitourinary and gastrointestinal toxicity. Int J Radiat Oncol Biol Phys 2010; 82:235-41. [PMID: 21163587 DOI: 10.1016/j.ijrobp.2010.09.058] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 09/03/2010] [Accepted: 09/21/2010] [Indexed: 12/14/2022]
Abstract
PURPOSE To characterize the late genitourinary (GU) and gastrointestinal (GI) toxicity for prostate cancer patients treated with intensity-modulated radiation therapy (IMRT) and propose dose-volume histogram (DVH) guidelines to limit late treatment-related toxicity. METHODS AND MATERIALS In this study 296 consecutive men were treated with IMRT for adenocarcinoma of the prostate. Most patients received treatment to the prostate with or without proximal seminal vesicles (90%), to a median dose of 76 Gy. Concurrent androgen deprivation therapy was given to 150 men (51%) for a median of 4 months. Late toxicity was defined by Common Toxicity Criteria version 3.0 as greater than 3 months after radiation therapy completion. Four groupings of DVH parameters were defined, based on the percentage of rectal or bladder tissue receiving 70 Gy (V(70)), 65 Gy (V(65)), and 40 Gy (V(40)). These DVH groupings, as well as clinical and treatment characteristics, were correlated to maximal Grade 2+ GU and GI toxicity. RESULTS With a median follow-up of 41 months, the 4-year freedom from maximal Grade 2+ late toxicity was 81% and 91% for GU and GI systems, respectively, and by last follow-up, the rates of Grade 2+ GU and GI toxicity were 9% and 5%, respectively. On multivariate analysis, whole-pelvic IMRT was associated with Grade 2+ GU toxicity and age was associated with Grade 2+ GI toxicity. Freedom from Grade 2+ GI toxicity at 4 years was 100% for men with rectal V(70) ≤ 10%, V(65) ≤ 20%, and V(40) ≤ 40%; 92% for men with rectal V(70) ≤ 20%, V(65) ≤ 40%, and V(40) ≤ 80%; and 85% for men exceeding these criteria (p = 0.13). These criteria were more highly associated with GI toxicity in men aged ≥70 years (p = 0.07). No bladder dose-volume relationships were associated with the risk of GU toxicity. CONCLUSIONS IMRT is associated with low rates of severe GU or GI toxicity after treatment for prostate cancer. Rectal dose constraints may help limit late GI morbidity.
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Affiliation(s)
- Aaron W Pederson
- Department of Radiation and Cellular Oncology, Pritzker School of Medicine, University of Chicago, Chicago, IL 60637, USA
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6
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Faria S, Joshua B, Patrocinio H, Dal Pra A, Cury F, Velly A, Souhami L. Searching for Optimal Dose–Volume Constraints to Reduce Rectal Toxicity after Hypofractionated Radiotherapy for Prostate Cancer. Clin Oncol (R Coll Radiol) 2010; 22:810-7. [DOI: 10.1016/j.clon.2010.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 05/13/2010] [Accepted: 05/20/2010] [Indexed: 10/18/2022]
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Nguyen PL, Chen RC, Hoffman KE, Trofimov A, Efstathiou JA, Coen JJ, Shipley WU, Zietman AL, Talcott JA. Rectal Dose–Volume Histogram Parameters Are Associated With Long-Term Patient-Reported Gastrointestinal Quality of Life After Conventional and High-Dose Radiation for Prostate Cancer: A Subgroup Analysis of a Randomized Trial. Int J Radiat Oncol Biol Phys 2010; 78:1081-5. [DOI: 10.1016/j.ijrobp.2009.09.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 09/13/2009] [Accepted: 09/14/2009] [Indexed: 11/15/2022]
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de Crevoisier R, Fiorino C, Dubray B. Radiothérapie prostatique : prédiction de la toxicité tardive à partir des données dosimétriques. Cancer Radiother 2010; 14:460-8. [DOI: 10.1016/j.canrad.2010.07.225] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 07/12/2010] [Indexed: 12/25/2022]
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Blanchard P, Chapet O. Dose de tolérance à l’irradiation des tissus sains : le rectum. Cancer Radiother 2010; 14:354-8. [DOI: 10.1016/j.canrad.2010.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 02/25/2010] [Indexed: 10/19/2022]
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Michalski JM, Gay H, Jackson A, Tucker SL, Deasy JO. Radiation dose-volume effects in radiation-induced rectal injury. Int J Radiat Oncol Biol Phys 2010; 76:S123-9. [PMID: 20171506 PMCID: PMC3319467 DOI: 10.1016/j.ijrobp.2009.03.078] [Citation(s) in RCA: 524] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 02/24/2009] [Accepted: 03/03/2009] [Indexed: 02/08/2023]
Abstract
The available dose/volume/outcome data for rectal injury were reviewed. The volume of rectum receiving >or=60 Gy is consistently associated with the risk of Grade >or=2 rectal toxicity or rectal bleeding. Parameters for the Lyman-Kutcher-Burman normal tissue complication probability model from four clinical series are remarkably consistent, suggesting that high doses are predominant in determining the risk of toxicity. The best overall estimates (95% confidence interval) of the Lyman-Kutcher-Burman model parameters are n = 0.09 (0.04-0.14); m = 0.13 (0.10-0.17); and TD(50) = 76.9 (73.7-80.1) Gy. Most of the models of late radiation toxicity come from three-dimensional conformal radiotherapy dose-escalation studies of early-stage prostate cancer. It is possible that intensity-modulated radiotherapy or proton beam dose distributions require modification of these models because of the inherent differences in low and intermediate dose distributions.
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Affiliation(s)
- Jeff M Michalski
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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11
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Gulliford SL, Foo K, Morgan RC, Aird EG, Bidmead AM, Critchley H, Evans PM, Gianolini S, Mayles WP, Moore AR, Sánchez-Nieto B, Partridge M, Sydes MR, Webb S, Dearnaley DP. Dose-volume constraints to reduce rectal side effects from prostate radiotherapy: evidence from MRC RT01 Trial ISRCTN 47772397. Int J Radiat Oncol Biol Phys 2010; 76:747-54. [PMID: 19540054 DOI: 10.1016/j.ijrobp.2009.02.025] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 02/11/2009] [Accepted: 02/11/2009] [Indexed: 11/24/2022]
Abstract
PURPOSE Radical radiotherapy for prostate cancer is effective but dose limited because of the proximity of normal tissues. Comprehensive dose-volume analysis of the incidence of clinically relevant late rectal toxicities could indicate how the dose to the rectum should be constrained. Previous emphasis has been on constraining the mid-to-high dose range (>/=50 Gy). Evidence is emerging that lower doses could also be important. METHODS AND MATERIALS Data from a large multicenter randomized trial were used to investigate the correlation between seven clinically relevant rectal toxicity endpoints (including patient- and clinician-reported outcomes) and an absolute 5% increase in the volume of rectum receiving the specified doses. The results were quantified using odds ratios. Rectal dose-volume constraints were applied retrospectively to investigate the association of constraints with the incidence of late rectal toxicity. RESULTS A statistically significant dose-volume response was observed for six of the seven endpoints for at least one of the dose levels tested in the range of 30-70 Gy. Statistically significant reductions in the incidence of these late rectal toxicities were observed for the group of patients whose treatment plans met specific proposed dose-volume constraints. The incidence of moderate/severe toxicity (any endpoint) decreased incrementally for patients whose treatment plans met increasing numbers of dose-volume constraints from the set of V30 CONCLUSION Considering the entire dose distribution to the rectum by applying dose-volume constraints such as those tested here in the present will reduce the incidence of late rectal toxicity.
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Affiliation(s)
- Sarah L Gulliford
- Joint Department of Physics, Institute of Cancer Research and Royal Marsden National Health Service Foundation Trust, Sutton, United Kingdom
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A prospective phase III randomized trial of hypofractionation versus conventional fractionation in patients with high-risk prostate cancer. Int J Radiat Oncol Biol Phys 2010; 78:11-8. [PMID: 20047800 DOI: 10.1016/j.ijrobp.2009.07.1691] [Citation(s) in RCA: 191] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 07/01/2009] [Accepted: 07/15/2009] [Indexed: 12/30/2022]
Abstract
PURPOSE To compare the toxicity and efficacy of hypofractionated (62 Gy/20 fractions/5 weeks, 4 fractions per week) vs. conventional fractionation radiotherapy (80 Gy/40 fractions/8 weeks) in patients with high-risk prostate cancer. METHODS AND MATERIALS From January 2003 to December 2007, 168 patients were randomized to receive either hypofractionated or conventional fractionated schedules of three-dimensional conformal radiotherapy to the prostate and seminal vesicles. All patients received a 9-month course of total androgen deprivation (TAD), and radiotherapy started 2 months thereafter. RESULTS The median (range) follow-up was 32 (8-66) and 35 (7-64) months in the hypofractionation and conventional fractionation arms, respectively. No difference was found for late toxicity between the two treatment groups, with 3-year Grade 2 rates of 17% and 16% for gastrointestinal and 14% and 11% for genitourinary in the hypofractionation and conventional fractionation groups, respectively. The 3-year freedom from biochemical failure (FFBF) rates were 87% and 79% in the hypofractionation and conventional fractionation groups, respectively (p = 0.035). The 3-year FFBF rates in patients at a very high risk (i.e., pretreatment prostate-specific antigen (iPSA) >20 ng/mL, Gleason score >or=8, or T >or=2c), were 88% and 76% (p = 0.014) in the former and latter arm, respectively. The multivariate Cox analysis confirmed fractionation, iPSA, and Gleason score as significant prognostic factors. CONCLUSIONS Our findings suggest that late toxicity is equivalent between the two treatment groups and that the hypofractionated schedule used in this trial is superior to the conventional fractionation in terms of FFBF.
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Effects of prostate-rectum separation on rectal dose from external beam radiotherapy. Int J Radiat Oncol Biol Phys 2009; 76:1251-8. [PMID: 19939577 DOI: 10.1016/j.ijrobp.2009.07.1679] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 07/15/2009] [Accepted: 07/16/2009] [Indexed: 11/23/2022]
Abstract
PURPOSE In radiotherapy for prostate cancer, the rectum is the major dose-limiting structure. Physically separating the rectum from the prostate (e.g., by injecting a spacer) can reduce the rectal radiation dose. Despite pilot clinical studies, no careful analysis has been done of the risks, benefits, and dosimetric effects of this practice. METHODS AND MATERIALS Using cadaveric specimens, 20 mL of a hydrogel was injected between the prostate and rectum using a transperineal approach. Imaging was performed before and after spacer placement, and the cadavers were subsequently dissected. Ten intensity-modulated radiotherapy plans were generated (five before and five after separation), allowing for characterization of the rectal dose reduction. To quantify the amount of prostate-rectum separation needed for effective rectal dose reduction, simulations were performed using nine clinically generated intensity-modulated radiotherapy plans. RESULTS In the cadaveric studies, an average of 12.5 mm of prostate-rectum separation was generated with the 20-mL hydrogel injections (the seminal vesicles were also separated from the rectum). The average rectal volume receiving 70 Gy decreased from 19.9% to 4.5% (p < .05). In the simulation studies, a prostate-rectum separation of 10 mm was sufficient to reduce the mean rectal volume receiving 70 Gy by 83.1% (p <.05). No additional reduction in the average rectal volume receiving 70 Gy was noted after 15 mm of separation. In addition, spacer placement allowed for increased planning target volume margins without exceeding the rectal dose tolerance. CONCLUSION Prostate-rectum spacers can allow for reduced rectal toxicity rates, treatment intensification, and/or reduced dependence on complex planning and treatment delivery techniques.
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Clinical and dosimetric predictors of late rectal toxicity after conformal radiation for localized prostate cancer: Results of a large multicenter observational study. Radiother Oncol 2009; 93:197-202. [DOI: 10.1016/j.radonc.2009.09.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 09/09/2009] [Accepted: 09/12/2009] [Indexed: 11/23/2022]
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Fiorino C, Valdagni R, Rancati T, Sanguineti G. Dose–volume effects for normal tissues in external radiotherapy: Pelvis. Radiother Oncol 2009; 93:153-67. [DOI: 10.1016/j.radonc.2009.08.004] [Citation(s) in RCA: 225] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 08/11/2009] [Accepted: 08/11/2009] [Indexed: 02/07/2023]
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Late Outcomes Following Hypofractionated Conformal Radiotherapy vs. Standard Fractionation for Localized Prostate Cancer: A Nonrandomized Contemporary Comparison. Int J Radiat Oncol Biol Phys 2009; 74:1441-6. [DOI: 10.1016/j.ijrobp.2008.10.087] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2008] [Revised: 09/30/2008] [Accepted: 10/12/2008] [Indexed: 11/18/2022]
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Gauthier I, Carrier JF, Béliveau-Nadeau D, Fortin B, Taussky D. Dosimetric Impact and Theoretical Clinical Benefits of Fiducial Markers for Dose Escalated Prostate Cancer Radiation Treatment. Int J Radiat Oncol Biol Phys 2009; 74:1128-33. [DOI: 10.1016/j.ijrobp.2008.09.043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 09/01/2008] [Accepted: 09/06/2008] [Indexed: 11/16/2022]
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Michalski JM, Roach M, Merrick G, Anscher MS, Beyer DC, Lawton CA, Lee WR, Pollack A, Rosenthal SA, Vijayakumar S, Carroll PR. ACR Appropriateness Criteria ® on External Beam Radiation Therapy Treatment Planning for Clinically Localized Prostate Cancer. Int J Radiat Oncol Biol Phys 2009; 74:667-72. [DOI: 10.1016/j.ijrobp.2008.12.073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 12/30/2008] [Accepted: 12/31/2008] [Indexed: 11/26/2022]
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Kim H, Lim DH, Paik SW, Yoo BC, Koh KG, Lee JH, Choi MS, Park W, Park HC, Huh SJ, Choi DH, Ahn YC. Predictive factors of gastroduodenal toxicity in cirrhotic patients after three-dimensional conformal radiotherapy for hepatocellular carcinoma. Radiother Oncol 2009; 93:302-6. [PMID: 19524314 DOI: 10.1016/j.radonc.2009.05.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 05/20/2009] [Accepted: 05/20/2009] [Indexed: 12/27/2022]
Abstract
BACKGROUND AND PURPOSE To identify predictive factors for the development of gastroduodenal toxicity (GDT) in cirrhotic patients treated with three-dimensional conformal radiotherapy (3D-CRT) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS We retrospectively analyzed dose-volume histograms (DVHs) and clinical records of 73 cirrhotic patients treated with 3D-CRT for HCC. The median radiation dose was 36 Gy (range, 30-54 Gy) with a daily dose of 3 Gy. The grade of GDT was defined by the Common Toxicity Criteria Version 2. The predictive factors of grade 3 GDT were identified. RESULTS Grade 3 GDT was found in 9 patients. Patient's age and the percentage of gastroduodenal volume receiving more than 35 Gy (V(35)) significantly affected the development of grade 3 GDT. Patients over 50 years of age developed grade 3 GDT more frequently than patients under 50 years of age. The risk of grade 3 GDT grew exponentially as V(35) increased. The 1-year actuarial rate of grade 3 GDT in patients with V(35)<5% is significantly lower than that in patients with a V(35)> or =5% (4% vs. 48%, p<.01). CONCLUSIONS Patient's age and V(35) were the most predictive factors for the development of grade 3 GDT in patients treated with RT.
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Affiliation(s)
- Haeyoung Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
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Inter-observer variability of prostate delineation on cone beam computerised tomography images. Clin Oncol (R Coll Radiol) 2008; 21:32-8. [PMID: 19058954 DOI: 10.1016/j.clon.2008.11.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Revised: 11/08/2008] [Accepted: 11/18/2008] [Indexed: 11/21/2022]
Abstract
AIM To determine the inter-observer variability of defining the prostate gland on cone beam computerised tomography images for the purposes of image-guided radiotherapy. MATERIALS AND METHODS Five genitourinary oncologists contoured the prostate gland on five cone beam computerised tomography datasets. The variations in prostate boundary delineation and consequent isocentre placement between observers were measured. Variations in volume and centre of mass were calculated. The variation in boundary definition was determined with finite element modelling. RESULTS The average standard deviation for centre of mass displacements was small, measuring 0.7, 1.8 and 2.8mm in the left-right, anterior-posterior and superior-inferior directions, respectively. The standard deviation for volume determination was 8.93 cm(3) with large variability (3.98-19.00 cm(3)). The mean difference between the computerised tomography-derived volume and the mean cone beam-derived volume was 16% (range 0-23.7%). The mean standard deviations for left-right, anterior-posterior and superior-inferior boundary displacements were, respectively, 1.8, 2.1 and 3.6 mm. The maximum deviation seen was 9.7 mm in the superior direction. CONCLUSION Expert observers had difficulty agreeing upon the location of the prostate peri-prostatic interface on the images provided. The effect on the centre of mass determination was small, and inter-observer variability for prostate detection on cone beam computerised tomography images is not prohibitive to the use of soft tissue guidance protocols. Potential exists for significant systematic matching errors, and points to the need for rigorous therapist image recognition training and development of guidance protocols before clinical implementation of soft tissue cone beam image guidance.
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Leborgne F, Fowler J. Acute Toxicity After Hypofractionated Conformal Radiotherapy for Localized Prostate Cancer: Nonrandomized Contemporary Comparison With Standard Fractionation. Int J Radiat Oncol Biol Phys 2008; 72:770-6. [DOI: 10.1016/j.ijrobp.2008.01.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 01/08/2008] [Accepted: 01/15/2008] [Indexed: 12/01/2022]
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Proposed Rectal Dose Constraints for Patients Undergoing Definitive Whole Pelvic Radiotherapy for Clinically Localized Prostate Cancer. Int J Radiat Oncol Biol Phys 2008; 72:69-77. [DOI: 10.1016/j.ijrobp.2007.12.045] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 12/10/2007] [Accepted: 12/11/2007] [Indexed: 11/22/2022]
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van der Laan HP, van den Bergh A, Schilstra C, Vlasman R, Meertens H, Langendijk JA. Grading-System-Dependent Volume Effects for Late Radiation-Induced Rectal Toxicity After Curative Radiotherapy for Prostate Cancer. Int J Radiat Oncol Biol Phys 2008; 70:1138-45. [DOI: 10.1016/j.ijrobp.2007.07.2363] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 07/30/2007] [Accepted: 07/31/2007] [Indexed: 11/12/2022]
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Fiorino C, Fellin G, Rancati T, Vavassori V, Bianchi C, Borca VC, Girelli G, Mapelli M, Menegotti L, Nava S, Valdagni R. Clinical and Dosimetric Predictors of Late Rectal Syndrome After 3D-CRT for Localized Prostate Cancer: Preliminary Results of a Multicenter Prospective Study. Int J Radiat Oncol Biol Phys 2008; 70:1130-7. [PMID: 17881142 DOI: 10.1016/j.ijrobp.2007.07.2354] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 07/24/2007] [Accepted: 07/24/2007] [Indexed: 11/30/2022]
Abstract
PURPOSE To assess the predictors of late rectal toxicity in a prospectively investigated group of patients treated at 70-80 Gy for prostate cancer (1.8-2 Gy fractions) with three-dimensional conformal radiotherapy. METHODS AND MATERIALS A total of 1,132 patients were entered into the study between 2002 and 2004. Three types of rectal toxicity, evaluated by a self-administered questionnaire, mainly based on the subjective objective management, analytic late effects of normal tissue system, were considered: stool frequency/tenesmus/pain, fecal incontinence, and bleeding. The data from 506 patients with a follow-up of 24 months were analyzed. The correlation between a number of clinical and dosimetric parameters and Grade 2 or greater toxicity was investigated by univariate and multivariate (MVA) logistic analyses. RESULTS Of the 1,132 patients, 21, 15, and 30 developed stool frequency/tenesmus/pain, fecal incontinence, and bleeding, respectively. Stool frequency/tenesmus/pain correlated with previous abdominal/pelvic surgery (MVA, p=0.05, odds ratio [OR], 3.3). With regard to incontinence, MVA showed the volume receiving>or=40 Gy (V40) (p=0.035, OR, 1.037) and surgery (p=0.02, OR, 4.4) to be the strongest predictors. V40 to V70 were highly predictive of bleeding; V70 showed the strongest impact on MVA (p=0.03), together with surgery (p=0.06, OR, 2.5), which was also the main predictor of Grade 3 bleeding (p=0.02, OR, 4.2). CONCLUSIONS The predictive value of the dose-volume histogram was confirmed for bleeding, consistent with previously suggested constraints (V50<55%, V60<40%, V70<25%, and V75<5%). A dose-volume histogram constraint for incontinence can be suggested (V40<65-70%). Previous abdominal/pelvic surgery correlated with all toxicity types; thus, a modified constraint for bleeding (V70<15%) can be suggested for patients with a history of abdominal/pelvis surgery, although further validation on a larger population with longer follow-up is needed.
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Affiliation(s)
- Claudio Fiorino
- Department of Medical Physics, Ospedale San Raffaele, Milan, Italy.
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Late gastrointestinal morbidity after three-dimensional conformal radiation therapy for prostate cancer fades with time in contrast to genitourinary morbidity. Int J Radiat Oncol Biol Phys 2007; 70:1478-86. [PMID: 18060703 DOI: 10.1016/j.ijrobp.2007.08.076] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 08/16/2007] [Accepted: 08/27/2007] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the incidence, time course, and relation to irradiated volumes of late morbidity after three-dimensional conformal radiation therapy (RT) for prostate cancer. METHODS AND MATERIALS From January 2000 to December 2001, a total of 247 patients with prostate cancer received a target dose of 70 Gy using conformal RT. Forty-eight patients (20%) received irradiation to the prostate only (Group P), 154 patients (62%) received irradiation to the prostate and seminal vesicles (Group PSV), and 45 patients (18%) received modified pelvic fields (Group MPF). Androgen deprivation was given to 86% of patients. Median follow-up was 62 months. Late gastrointestinal (GI) and genitourinary (GU) morbidity were recorded according to the Radiation Therapy Oncology Group scoring system. RESULTS We observed 9%, 7%, and 25% Grade 2 or higher GI morbidity and 36%, 30%, and 21% Grade 2 or higher GU morbidity in Groups P, PSV, and MPF, respectively. In multivariate analyses, age and treatment group were independent predictors for the incidence of late Grade 2 or higher GI morbidity, whereas age and urinary symptoms before treatment were independent predictors for late Grade 2 or higher GU morbidity. Acute side effects predicted for late effects. The rectum dose-volume histogram parameters correlated with the incidence of late Grade 2 or higher GI morbidity, especially the fractional volume receiving more than 40-43 Gy. At 5 years of follow-up, the rate of Grade 2 late GI morbidity was only 1.4%, and Grade 2 or higher GU morbidity was 10.6%. CONCLUSIONS The data presented here show that late GI morbidity after prostate RT is low and subsides with time.
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Kuban DA, Tucker SL, Dong L, Starkschall G, Huang EH, Cheung MR, Lee AK, Pollack A. Long-term results of the M. D. Anderson randomized dose-escalation trial for prostate cancer. Int J Radiat Oncol Biol Phys 2007; 70:67-74. [PMID: 17765406 DOI: 10.1016/j.ijrobp.2007.06.054] [Citation(s) in RCA: 923] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 06/29/2007] [Accepted: 06/30/2007] [Indexed: 12/12/2022]
Abstract
PURPOSE To report the long-term results of a randomized radiotherapy dose escalation trial for prostate cancer. METHODS AND MATERIALS From 1993 to 1998, a total of 301 patients with stage T1b to T3 prostate cancer were accrued to a randomized external beam dose escalation trial using 70 Gy versus 78 Gy. The median follow-up is now 8.7 years. Kaplan-Meier analysis was used to compute rates of prostate-specific antigen (PSA) failure (nadir + 2), clinical failure, distant metastasis, disease-specific, and overall survival as well as complication rates at 8 years post-treatment. RESULTS For all patients, freedom from biochemical or clinical failure (FFF) was superior for the 78-Gy arm, 78%, as compared with 59% for the 70-Gy arm (p = 0.004, and an even greater benefit was seen in patients with initial PSA >10 ng/ml (78% vs. 39%, p = 0.001). The clinical failure rate was significantly reduced in the 78-Gy arm as well (7% vs. 15%, p = 0.014). Twice as many patients either died of prostate cancer or are currently alive with cancer in the 70-Gy arm. Gastrointestinal toxicity of grade 2 or greater occurred twice as often in the high dose patients (26% vs. 13%), although genitourinary toxicity of grade 2 or greater was less (13% vs. 8%) and not statistically significantly different. Dose-volume histogram analysis showed that the complication rate could be significantly decreased by reducing the amount of treated rectum. CONCLUSIONS Modest escalation in radiotherapy dose improved freedom from biochemical and clinical progression with the largest benefit in prostate cancer patients with PSA >10 ng/ml.
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Affiliation(s)
- Deborah A Kuban
- Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
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Milano MT, Constine LS, Okunieff P. Normal Tissue Tolerance Dose Metrics for Radiation Therapy of Major Organs. Semin Radiat Oncol 2007; 17:131-40. [PMID: 17395043 DOI: 10.1016/j.semradonc.2006.11.009] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Late organ toxicity from therapeutic radiation is a function of many confounding variables. The total dose delivered to the organ and the volumes of organ exposed to a given dose of radiation are 2 important variables that can be used to predict the risk of late toxicity. Three-dimensional radiation planning enables accurate calculation of the volume of tissue exposed to a given dose of radiation, graphically depicted as a dose-volume histogram. Dose metrics obtained from this 3-dimensional dataset can be used as a quantitative measure to predict late toxicity. This review summarizes the published clinical data on the risk of late toxicity as a function of quantitative dose metrics and attempts to offer suggested dose constraints for radiation treatment planning.
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Affiliation(s)
- Michael T Milano
- Department of Radiation Oncology and James P. Wilmot Cancer Center, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
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Fowler JF. Is There an Optimum Overall Time for Head and Neck Radiotherapy? A Review, with New Modelling. Clin Oncol (R Coll Radiol) 2007; 19:8-22. [PMID: 17305251 DOI: 10.1016/j.clon.2006.09.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AIMS To test by modelling whether a non-standard fractionated schedule giving optimum log cell kill could be expected, between short (accelerated) and longer multiple fraction/day schedules. MATERIALS AND METHODS Linear quadratic modelling was carried out for many schedules, with biologically effective doses converted to normalised total doses (NTDs; in 2 Gy fractions). Late complication and acute mucosal NTDs were calculated as constraint doses for each schedule, and the highest tumour NTDs and log cell kill values within both constraints were calculated. This modelling is robust and agrees with conclusions in a very recent meta-analysis (Bourhis J, Overgaard J, Audry H, et al. Hyperfractionated or accelerated radiotherapy in head and neck cancer: a meta-analysis. www.thelancet.com. Published online August 17, 2006). RESULTS The six schedules that gave the highest tumour log cell kill deliver a narrow range of 11.1-11.2 log10 cell kill in the present parameters. Other regularly used schedules give closer to 10 log10. Using one fraction/day fails to achieve the highest therapeutic ratios. Suggestions are made for escalating certain UK schedules. Fractionated radiotherapy results in a nearly constant tumour cell kill if the acute mucosal NTD is held constant. However, a small (3%) gain in tumour cell kill occurs from 3 weeks to 73 fractions of 1.15 Gy in 7 weeks. That is how fractionation works, within both acute and late constraints. Short accelerated schedules enable fewer late complications, but do not do as well for the minority of head and neck tumours that repopulate slowly. CONCLUSIONS Schedules of 4-6 weeks overall time could be chosen to give at least 11 log10 cell kill, which are safe. Most tumours would require two fractions/day, until routine monitoring of repopulation rates becomes feasible to select individual tumours. There is no 'optimum schedule', but each chosen schedule can be balanced against its own risk of excessive acute or late complications, as shown in these examples.
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Affiliation(s)
- J F Fowler
- Department of Human Oncology, University of Wisconsin Medical School, Madison, WI 53792, USA.
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Vavassori V, Fiorino C, Rancati T, Magli A, Fellin G, Baccolini M, Bianchi C, Cagna E, Mauro FA, Monti AF, Munoz F, Stasi M, Franzone P, Valdagni R. Predictors for rectal and intestinal acute toxicities during prostate cancer high-dose 3D-CRT: results of a prospective multicenter study. Int J Radiat Oncol Biol Phys 2007; 67:1401-10. [PMID: 17241754 DOI: 10.1016/j.ijrobp.2006.10.040] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 09/26/2006] [Accepted: 10/30/2006] [Indexed: 11/15/2022]
Abstract
PURPOSE To find predictors for rectal and intestinal acute toxicity in patients with prostate cancer treated with > or =70 Gy conformal radiotherapy. METHODS AND MATERIALS Between July 2002 and March 2004, 1,132 patients were entered into a cooperative study (AIROPROS01-02). Toxicity was scored using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale and by considering the changes (before and after treatment) of the scores of a self-administered questionnaire on rectal/intestinal toxicity. The correlation with a number of parameters was assessed by univariate and multivariate analyses. Concerning the questionnaire, only moderate/severe complications were considered. RESULTS Of 1,132 patients, 1,123 were evaluable. Of these patients, 375, 265, and 28 had Grade 1, 2, and 3 Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity, respectively. The mean rectal dose was the most predictive parameter (p = 0.0004; odds ratio, 1.035) for Grade 2 or worse toxicity, and the use of anticoagulants/antiaggregants (p = 0.02; odds ratio, 0.63) and hormonal therapy (p = 0.04, odds ratio, 0.65) were protective. The questionnaire-based scoring revealed that a greater mean rectal dose was associated with a greater risk of bleeding; larger irradiated volumes were associated with frequency, tenesmus, incontinence, and bleeding; hormonal therapy was protective against frequency and tenesmus; hemorrhoids were associated with a greater risk of tenesmus and bleeding; and diabetes associated highly with diarrhea. CONCLUSION The mean rectal dose correlated with acute rectal/intestinal toxicity in three-dimensional conformal radiotherapy for prostate cancer, and hormonal therapy and the use of anticoagulants/antiaggregants were protective. According to the moderate/severe injury scores on the self-assessed questionnaire, several clinical and dose-volume parameters were independently predictive for particular symptoms.
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Garg AK, Mai WY, McGary JE, Grant WH, Butler EB, Teh BS. Radiation proctopathy in the treatment of prostate cancer. Int J Radiat Oncol Biol Phys 2007; 66:1294-305. [PMID: 17126204 DOI: 10.1016/j.ijrobp.2006.07.1386] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 06/13/2006] [Accepted: 07/06/2006] [Indexed: 12/13/2022]
Abstract
PURPOSE To compile and review data on radiation proctopathy in the treatment of prostate cancer with respect to epidemiology, clinical manifestations, pathogenesis, risk factors, and treatment. METHODS Medical literature databases including PubMed and Medline were screened for pertinent reports, and critically analyzed for relevance in the scope of our purpose. RESULTS Rectal toxicity as a complication of radiotherapy has received attention over the past decade, especially with the advent of dose-escalation in prostate cancer treatment. A number of clinical criteria help to define acute and chronic radiation proctopathy, but lack of a unified grading scale makes comparing studies difficult. A variety of risk factors, related to either radiation delivery or patient, are the subject of intense study. Also, a variety of treatment options, including medical therapy, endoscopic treatments, and surgery have shown varied results, but a lack of large randomized trials evaluating their efficacy prevents forming concrete recommendations. CONCLUSION Radiation proctopathy should be an important consideration for the clinician in the treatment of prostate cancer especially with dose escalation. With further study of possible risk factors, the advent of a standardized grading scale, and more randomized trials to evaluate treatments, patients and physicians will be better armed to make appropriate management decisions.
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Affiliation(s)
- Amit K Garg
- Department of Radiation Oncology, MD Anderson Cancer Center, Houston, TX, USA
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van Lin ENJT, Kristinsson J, Philippens MEP, de Jong DJ, van der Vight LP, Kaanders JHAM, Leer JW, Visser AG. Reduced late rectal mucosal changes after prostate three-dimensional conformal radiotherapy with endorectal balloon as observed in repeated endoscopy. Int J Radiat Oncol Biol Phys 2006; 67:799-811. [PMID: 17161552 DOI: 10.1016/j.ijrobp.2006.09.034] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Revised: 08/31/2006] [Accepted: 09/19/2006] [Indexed: 10/23/2022]
Abstract
PURPOSE The aim of this study was to investigate prospectively the rectal wall (Rwall) spatial dose distribution, toxicity, and mucosal changes after prostate cancer radiotherapy with or without an endorectal balloon (ERB). METHODS AND MATERIALS A total of 24 patients with ERB and 24 without ERB (No-ERB) were treated with three-dimensional conformal radiotherapy (3D-CRT) to a dose of 67.5 Gy. The Rwall was divided into 16 mucosal areas and Rwall dose surface maps were constructed. After 3 months, 6 months, 1 year, and 2 years a rectosigmoidoscopy was performed, and each mucosal area was scored on telangiectasia, congestion, ulceration, stricture, and necrosis. Late rectal toxicity was correlated with the endoscopic findings. RESULTS The ERB significantly reduced the Rwall volume exposed to doses >40 Gy. Late rectal toxicity (grade >or=1, including excess of bowel movements and slight rectal discharge) was reduced significantly in the ERB group. A total of 146 endoscopies and 2,336 mucosal areas were analyzed. Telangiectases were most frequently seen and appeared after 6 months. At 1 and 2 years, significantly less high-grade telangiectasia (T 2-3) was observed in the ERB group at the lateral and posterior part of the Rwall. In mucosal areas exposed to doses >40 Gy, less high-grade telangiectases (T 2-3) were seen in the ERB group compared with the No-ERB group. CONCLUSIONS An ERB reduced the Rwall volume exposed to doses >40 Gy, resulting in reduction of late rectal mucosal changes and reduced late rectal toxicity. Although further analysis is needed, these data suggest an ERB-induced increased tolerance for late Rwall damage.
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Affiliation(s)
- Emile N J Th van Lin
- Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Luo C, Yang CC, Narayan S, Stern RL, Perks J, Goldberg Z, Ryu J, Purdy JA, Vijayakumar S. Use of benchmark dose–volume histograms for selection of the optimal technique between three-dimensional conformal radiation therapy and intensity-modulated radiation therapy in prostate cancer. Int J Radiat Oncol Biol Phys 2006; 66:1253-62. [PMID: 17145540 DOI: 10.1016/j.ijrobp.2006.06.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 06/04/2006] [Accepted: 06/06/2006] [Indexed: 11/28/2022]
Abstract
PURPOSE The aim of this study was to develop and validate our own benchmark dose-volume histograms (DVHs) of bladder and rectum for both conventional three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), and to evaluate quantitatively the benefits of using IMRT vs. 3D-CRT in treating localized prostate cancer. METHODS AND MATERIALS During the implementation of IMRT for prostate cancer, our policy was to plan each patient with both 3D-CRT and IMRT. This study included 31 patients with T1b to T2c localized prostate cancer, for whom we completed double-planning using both 3D-CRT and IMRT techniques. The target volumes included prostate, either with or without proximal seminal vesicles. Bladder and rectum DVH data were summarized to obtain an average DVH for each technique and then compared using two-tailed paired t test analysis. RESULTS For 3D-CRT our bladder doses were as follows: mean 28.8 Gy, v60 16.4%, v70 10.9%; rectal doses were: mean 39.3 Gy, v60 21.8%, v70 13.6%. IMRT plans resulted in similar mean dose values: bladder 26.4 Gy, rectum 34.9 Gy, but lower values of v70 for the bladder (7.8%) and rectum (9.3%). These benchmark DVHs have resulted in a critical evaluation of our 3D-CRT techniques over time. CONCLUSION Our institution has developed benchmark DVHs for bladder and rectum based on our clinical experience with 3D-CRT and IMRT. We use these standards as well as differences in individual cases to make decisions on whether patients may benefit from IMRT treatment rather than 3D-CRT.
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Affiliation(s)
- Chunhui Luo
- Radiation Oncology, University of California Davis Medical Center, Sacramento, CA 95817, USA
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Chin YS, Bullard J, Bryant L, Bownes P, Ostler P, Hoskin PJ. High Dose Rate Iridium-192 Brachytherapy as a Component of Radical Radiotherapy for the Treatment of Localised Prostate Cancer. Clin Oncol (R Coll Radiol) 2006; 18:474-9. [PMID: 16909971 DOI: 10.1016/j.clon.2006.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
AIMS To assess the treatment outcomes and toxicity of conformal high dose rate (HDR) brachytherapy boost as a means of radiation dose escalation in patients with localised prostate cancer. MATERIALS AND METHODS Between December 1998 and July 2004, 65 consecutive patients with localised prostate cancer (magnetic resonance imaging-staged T1-3 N0 M0) were treated with external beam radiation therapy (EBRT) followed by two fractions of HDR iridium-192 brachytherapy. The patients selected this treatment modality in preference to entering an ongoing randomised phase 3 trial. Any pre-treatment serum prostate-specific antigen (PSA) and Gleason score were included. The primary end point was biochemical disease-free progression. Late treatment-related morbidity was graded according to the Radiation Therapy Oncology Group and the European Organization for Research and Treatment of Cancer criteria. RESULTS The median patient age was 67.3 years (range 47.9-80). Sixty patients (92.3%) had intermediate- to high-risk disease defined by clinical stage, presenting PSA and Gleason score/World Health Organisation (WHO) grade. With a median follow-up of 3.5 years (range 0.6-5.8), two patients had died of metastatic disease and another four patients had PSA relapse, giving a 3-year actuarial biochemical disease-free progression of 90.8%. Three patients (4.6%) had acute grade 3 genitourinary toxicity, in the form of urinary retention. Late grade 3 and 4 genitourinary toxicities occurred in four patients (6.2%) and one patient (1.5%), respectively. No late gastrointestinal toxicities were observed. CONCLUSIONS These results suggest that the combined modality of conformal HDR brachytherapy and EBRT is a feasible treatment modality with acceptable acute and late toxicities, comparable with those of EBRT alone. It offers an attractive conformal treatment modality with the potential of further dose escalation in the treatment of localised prostate cancer.
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Affiliation(s)
- Y S Chin
- Mount Vernon Centre for Cancer Treatment, Northwood, Middlesex, UK
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Bracarda S, de Cobelli O, Greco C, Prayer-Galetti T, Valdagni R, Gatta G, de Braud F, Bartsch G. Cancer of the prostate. Crit Rev Oncol Hematol 2005; 56:379-96. [PMID: 16310371 DOI: 10.1016/j.critrevonc.2005.03.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 03/16/2005] [Indexed: 11/24/2022] Open
Abstract
Prostate carcinoma, with about 190,000 new cases occurring each year (15% of all cancers in men), is the most frequent cancer among men in northern and western Europe. Causes of the disease are essentially unknown, although hormonal factors are involved, and diet may exert an indirect influence; some genes, potentially involved in hereditary prostate cancer (HPC) have been identified. A suspect of prostate cancer may derive from elevated serum prostate-specific antigen (PSA) values and/or a suspicious digital rectal examination (DRE) finding. For a definitive diagnosis, however, a positive prostate biopsy is requested. Treatment strategy is defined according to initial PSA stage, and grade of the disease and age and general conditions of the patient. In localized disease, watchful waiting is indicated as primary option in patients with well or moderately differentiated tumours and a life expectancy <10 years, while radical prostatectomy and radiotherapy (with or without hormone-therapy) could be appropriate choices in the remaining cases. Hormone-therapy is the treatment of choice, combined with radiotherapy, for locally advanced or bulky disease and is effective, but not curative, in 80-85% of the cases of advanced disease. Patients who develop a hormone-refractory prostate cancer disease (HRPC) have to be evaluated for chemotherapy because of the recent demonstration of improved overall survival (2-2.5 months) and quality of life with docetaxel in more than 1,600 cases.
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Odrazka K, Zouhar M, Petera J, Vaculikova M, Dolezel M, Vosmik M, Tucek P. Comparison of rectal dose-volume constraints for IMRT prostate treatment planning. Phys Med 2005; 21:129-35. [DOI: 10.1016/s1120-1797(05)80001-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 07/18/2005] [Accepted: 07/20/2005] [Indexed: 11/16/2022] Open
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Heemsbergen WD, Hoogeman MS, Hart GAM, Lebesque JV, Koper PCM. Gastrointestinal toxicity and its relation to dose distributions in the anorectal region of prostate cancer patients treated with radiotherapy. Int J Radiat Oncol Biol Phys 2005; 61:1011-8. [PMID: 15752880 DOI: 10.1016/j.ijrobp.2004.07.724] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Revised: 07/23/2004] [Accepted: 07/23/2004] [Indexed: 10/25/2022]
Abstract
PURPOSE To study the correlations between the dose distributions in the anorectal region and late GI symptoms in patients treated for localized prostate carcinoma. METHODS AND MATERIALS Data from a randomized study were analyzed. In this trial, patients were treated with either rectangular or conformal fields with a dose of 66 Gy. Data concerning GI symptoms were collected from questionnaires of 197 patients. The distributions of the anorectal region were projected on maps, and the dose parameters were calculated. The incidences of complaints were studied as a function of the dose-area parameters and clinical parameters, using a proportional hazard regression model. Finally, we tested a series of dose parameters originating from different parts of the anorectal region. RESULTS Analyzing the total region, only a statistically significant dose-area effect relation for bleeding was found (p < 0.01). Defining subareas, we found effect relations for bleeding, soiling, fecal incontinence, and mucus loss. For bleeding and mucus loss, the strongest correlation was found for the dose received by the upper 70-80% of the anorectal region (p < 0.01). For soiling and fecal incontinence, we found the strongest association with the dose to the lower 40-50% (p < 0.05). CONCLUSION We found evidence that complaints originate from specific regions of the irradiated lower GI tract. Bleeding and mucus loss are probably related to irradiation of the upper part of the rectum. Soiling and fecal incontinence are more likely related to the dose to the anal canal and the lower part of the rectum.
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Affiliation(s)
- Wilma D Heemsbergen
- Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
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D'Souza WD, Ahamad AA, Iyer RB, Salehpour MR, Jhingran A, Eifel PJ. Feasibility of dose escalation using intensity-modulated radiotherapy in posthysterectomy cervical carcinoma. Int J Radiat Oncol Biol Phys 2005; 61:1062-70. [PMID: 15752885 DOI: 10.1016/j.ijrobp.2004.07.721] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Revised: 07/13/2004] [Accepted: 07/15/2004] [Indexed: 11/21/2022]
Abstract
PURPOSE To evaluate retrospectively the utility of intensity-modulated radiotherapy (IMRT) in reducing the volume of normal tissues receiving radiation at varying dose levels when the female pelvis after hysterectomy is treated to doses of 50.4 Gy and 54 Gy. METHODS AND MATERIALS Computed tomography scans from 10 patients who had previously undergone conventional postoperative RT were selected. The clinical tumor volume (vaginal apex and iliac nodes) and organs at risk were contoured. Margins were added to generate the planning tumor volume. The Pinnacle and Corvus planning systems were used to develop conventional and IMRT plans, respectively. Conventional four-field plans were prescribed to deliver 45 Gy (4F(45 Gy)) or 50.4 Gy; eight-field IMRT plans were prescribed to deliver 50.4 Gy (IMRT(50.4 Gy)) or 54 Gy (IMRT(54 Gy)) to the planning tumor volume. All plans were normalized so that > or =97% of the planning tumor volume received the prescribed dose. Student's t test was used to compare the volumes of organs at risk receiving the same doses with different plans. RESULTS The mean volume of bowel receiving > or =45 Gy was lower with the IMRT(50.4 Gy) (33% lower) and IMRT(54 Gy) (18% lower) plans than with the 4F(45 Gy) plan. The mean volume of rectum receiving > or =45 Gy or > or =50 Gy was also significantly reduced with the IMRT plans despite an escalation of the prescribed dose from 45 Gy with the conventional plans to 54 Gy with IMRT. The mean volume of bladder treated to 45 Gy was the same or slightly lower with the IMRT(50.4 Gy) and IMRT(54 Gy) plans compared with the 4F(45 Gy) plan. Compared with the 4F(45 Gy) plan, the IMRT(50.4 Gy) plan resulted in a smaller volume of bowel receiving 35-45 Gy and a larger volume of bowel receiving 50-55 Gy. Compared with the 4F(45 Gy) plan, the IMRT(54 Gy) plan resulted in smaller volumes of bowel receiving 45-50 Gy; however, small volumes of bowel received 55-60 Gy with the IMRT plan. CONCLUSION Intensity-modulated RT may permit an increase in the radiation dose that can safely be delivered to the central pelvis and pelvic lymph nodes after hysterectomy. However, dose-volume calculations using individual CT scans do not account for internal organ motion. Detailed data concerning the relationships among radiation dose, treatment volume, and treatment effects are lacking, and prospective studies of pelvic IMRT are needed to determine the safety and efficacy of this treatment.
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Affiliation(s)
- Warren D D'Souza
- Division of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX, USA.
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Rancati T, Fiorino C, Gagliardi G, Cattaneo GM, Sanguineti G, Borca VC, Cozzarini C, Fellin G, Foppiano F, Girelli G, Menegotti L, Piazzolla A, Vavassori V, Valdagni R. Fitting late rectal bleeding data using different NTCP models: results from an Italian multi-centric study (AIROPROS0101). Radiother Oncol 2005; 73:21-32. [PMID: 15465142 DOI: 10.1016/j.radonc.2004.08.013] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2004] [Revised: 08/02/2004] [Accepted: 08/11/2004] [Indexed: 11/22/2022]
Abstract
BACKGROUND AND PURPOSE Recent investigations demonstrated a significant correlation between rectal dose-volume patterns and late rectal toxicity. The reduction of the DVH to a value expressing the probability of complication would be suitable. To fit different normal tissue complication probability (NTCP) models to clinical outcome on late rectal bleeding after external beam radiotherapy (RT) for prostate cancer. PATIENTS AND METHODS Rectal dose-volume histograms of the rectum (DVH) and clinical records of 547 prostate cancer patients (pts) pooled from five institutions previously collected and analyzed were considered. All patients were treated in supine position with 3 or 4-field techniques: 123 patients received an ICRU dose between 64 and 70 Gy, 255 patients between 70 and 74 Gy and 169 patients between 74 and 79.2 Gy; 457/547 patients were treated with conformal RT and 203/547 underwent radical prostatectomy before RT. Minimum follow-up was 18 months. Patients were considered as bleeders if showing grade 2/3 late bleeding (slightly modified RTOG/EORTC scoring system) within 18 months after the end of RT. Four NTCP models were considered: (a) the Lyman model with DVH reduced to the equivalent uniform dose (LEUD, coincident with the classical Lyman-Kutcher-Burman, LKB, model), (b) logistic with DVH reduced to EUD (LOGEUD), (c) Poisson coupled to EUD reduction scheme and (d) relative seriality (RS). The parameters for the different models were fit to the patient data using a maximum likelihood analysis. The 68% confidence intervals (CI) of each parameter were also derived. RESULTS Forty six out of five hundred and forty seven patients experienced grade 2/3 late bleeding: 38/46 developed rectal bleeding within 18 months and were then considered as bleeders The risk of rectal bleeding can be well calculated with a 'smooth' function of EUD (with a seriality parameter n equal to 0.23 (CI 0.05), best fit result). Using LEUD the relationship between EUD and NTCP can be described with a TD50 of 81.9 Gy (CI 1.8 Gy) and a steepness parameter m of 0.19 (CI 0.01); when using LOGEUD, TD50 is 82.2 Gy and k is 7.85. Best fit parameters for RS are s=0.49, gamma=1.69, TD50=83.1 Gy. Qualitative as well as quantitative comparisons (chi-squared statistics, P=0.005) show that the models fit the observed complication rates very well. The results found in the overall population were substantially confirmed in the subgroup of radically treated patients (LEUD: n=0.24 m=0.14 TD50=75.8 Gy). If considering just the grade 3 bleeders (n=9) the best fit is found in correspondence of a n-value around 0.06, suggesting that for severe bleeding the rectum is more serial. CONCLUSIONS Different NTCP models fit quite accurately the considered clinical data. The results are consistent with a rectum 'less serial' than previously reported investigations when considering grade 2 bleeding while a more serial behaviour was found for severe bleeding. EUD may be considered as a robust and simple parameter correlated with the risk of late rectal bleeding.
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Affiliation(s)
- T Rancati
- Department of Physics, University of Milan, Milan, Italy
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Tucker SL, Dong L, Cheung R, Johnson J, Mohan R, Huang EH, Liu HH, Thames HD, Kuban D. Comparison of rectal dose-wall histogram versus dose-volume histogram for modeling the incidence of late rectal bleeding after radiotherapy. Int J Radiat Oncol Biol Phys 2005; 60:1589-601. [PMID: 15590191 DOI: 10.1016/j.ijrobp.2004.07.712] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2004] [Revised: 07/12/2004] [Accepted: 07/14/2004] [Indexed: 01/27/2023]
Abstract
PURPOSE To compare the fits of normal-tissue complication probability (NTCP) models based on rectal dose-wall histograms (DWHs) vs. dose-volume histograms (DVHs) when the two are used to analyze a common set of late rectal toxicity data. METHODS AND MATERIALS Data were analyzed from 128 prostate cancer patients treated with 3-dimensional conformal radiotherapy (3D-CRT) at The University of Texas M.D. Anderson Cancer Center (UTMDACC). The DVH for total rectal volume, including contents, was obtained for each patient from the treatment-planning system. A DWH was also computed, using the outer rectal contour plus an autogenerated inner contour that corresponds to an assumed 3-mm rectal wall thickness. The endpoint for analysis was Grade 2 or higher late rectal bleeding within 2 years of treatment; all patients had at least 2 years of follow-up. Four different NTCP models were fitted to the response data by using either the DVH or the DWH to describe the dose distribution to rectum or rectal wall, respectively. The 4 models considered were the Lyman model, the mean dose model, the parallel-architecture model, and a model based on the volume of a organ receiving more than a specified dose (the "cutoff-dose" model). RESULTS For each of the models, the fit to the late rectal bleeding data was slightly improved when the analysis was based on the rectal DWH instead of on the DVH. In addition, the results of the cutoff dose and parallel architecture models were consistent with one another for the DWH data but not for the DVH data. For the DWH data, both models predict a 50% or higher incidence of Grade 2 or worse late rectal bleeding within 2 years if 80% or more of the rectal wall is exposed to doses greater than 32 Gy. A 50% or higher incidence of rectal bleeding is also predicted if the mean dose to rectal wall exceeds 53.2 Gy. CONCLUSIONS A consistent, although modest, improvement occurs in the fits of NTCP models to the UTMDACC 2-year late rectal bleeding data when the fit is based on the rectal dose-wall histogram instead of on the dose-volume histogram for entire rectum, including contents.
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Affiliation(s)
- Susan L Tucker
- Department of Biostatistics and Applied Mathematics, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
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Chauvet I, Gaboriaud G, Pontvert D, Zefkili S, Giraud P, Rosenwald JC, Cosset JM. Choix des contraintes et amélioration dosimétrique d’une radiothérapie conformationnelle du cancer de la prostate modulée en intensité pendant une partie du traitement. Cancer Radiother 2004; 8:337-51. [PMID: 15619378 DOI: 10.1016/j.canrad.2004.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 09/29/2004] [Accepted: 09/30/2004] [Indexed: 11/20/2022]
Abstract
PURPOSE Intensity modulated radiation therapy (IMRT) is based on a methodology called inverse planning. Starting from dosimetric objectives, constraints of optimization are fixed and given to the inverse planning system, which in turn calculates the modulated intensity to apply to each beam. Since the algorithms allow the constraints to be violated, the results of optimization may differ from the initial dosimetric objectives. Consequently, the user is compelled to adapt the choice of the constraints according to the type of modulation and until satisfactory results are found. The purpose of this work is to present our experience in the choice of these constraints for prostate cancer treatments, as we moved from conformal radiotherapy to IMRT. Treatments were performed with a Varian 23EX linac and calculations were realized with the Varian CadPlan-Helios planning system. PATIENTS AND METHODS The approach used for the first 12 patients treated at institut Curie with IMRT from June 2002 was analysed. The treatment always consisted of a combination of conformal radiotherapy with and without intensity modulation. RESULTS AND CONCLUSION Results showed that, a larger fraction of the treatment performed with IMRT induced a better sparing of the organs at risk for the same homogeneous dose distribution to the target volume. Apart from the dose-volume constraint for the rectum, a fixed set of constraints, slightly more restrictive than the dosimetric objectives, could be used for all patients. Compared with conformal radiotherapy, the conformation factor for IMRT increased up to 16%. A specific study was undertaken in view of treatments completely performed with IMRT. The optimal technique consisted in performing separated IMRT plans for the two target volumes, the prostate volume and the prostate plus seminal vesicles volume respectively. Another satisfactory possibility was to define new constraints on two separated planning target volumes, prostate and seminal vesicles. This last approach is now routinely implemented for our IMRT patients.
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Affiliation(s)
- I Chauvet
- Département de radiothérapie, institut Curie, 26, rue d'Ulm, 75005 Paris, France
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Ghilezan M, Yan D, Liang J, Jaffray D, Wong J, Martinez A. Online image-guided intensity-modulated radiotherapy for prostate cancer: How much improvement can we expect? A theoretical assessment of clinical benefits and potential dose escalation by improving precision and accuracy of radiation delivery. Int J Radiat Oncol Biol Phys 2004; 60:1602-10. [PMID: 15590192 DOI: 10.1016/j.ijrobp.2004.07.709] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 07/12/2004] [Accepted: 07/14/2004] [Indexed: 11/27/2022]
Abstract
PURPOSE To quantify the theoretical benefit, in terms of improvement in precision and accuracy of treatment delivery and in dose increase, of using online image-guided intensity-modulated radiotherapy (IG-IMRT) performed with onboard cone-beam computed tomography (CT), in an ideal setting of no intrafraction motion/deformation, in the treatment of prostate cancer. METHODS AND MATERIALS Twenty-two prostate cancer patients treated with conventional radiotherapy underwent multiple serial CT scans (median 18 scans per patient) during their treatment. We assumed that these data sets were equivalent to image sets obtainable by an onboard cone-beam CT. Each patient treatment was simulated with conventional IMRT and online IG-IMRT separately. The conventional IMRT plan was generated on the basis of pretreatment CT, with a clinical target volume to planning target volume (CTV-to-PTV) margin of 1 cm, and the online IG-IMRT plan was created before each treatment fraction on the basis of the CT scan of the day, without CTV-to-PTV margin. The inverse planning process was similar for both conventional IMRT and online IG-IMRT. Treatment dose for each organ of interest was quantified, including patient daily setup error and internal organ motion/deformation. We used generalized equivalent uniform dose (EUD) to compare the two approaches. The generalized EUD (percentage) of each organ of interest was scaled relative to the prescription dose at treatment isocenter for evaluation and comparison. On the basis of bladder wall and rectal wall EUD, a dose-escalation coefficient was calculated, representing the potential increment of the treatment dose achievable with online IG-IMRT as compared with conventional IMRT. RESULTS With respect to radiosensitive tumor, the average EUD for the target (prostate plus seminal vesicles) was 96.8% for conventional IMRT and 98.9% for online IG-IMRT, with standard deviations (SDs) of 5.6% and 0.7%, respectively (p < 0.0001). The average EUDs of bladder wall and rectal wall for conventional IMRT vs. online IG-IMRT were 70.1% vs. 47.3%, and 79.4% vs. 72.2%, respectively. On average, a target dose increase of 13% (SD = 9.7%) can be achieved with online IG-IMRT based on rectal wall EUDs and 53.3% (SD = 15.3%) based on bladder wall EUDs. However, the variation (SD = 9.7%) is fairly large among patients; 27% of patients had only minimal benefit (<5% of dose increment) from online IG-IMRT, and 32% had significant benefit (>15%-41% of dose increment). CONCLUSIONS The ideal maximum dose increment achievable with online IG-IMRT is, on average, 13% with respect to the dose-limiting organ of rectum. However, there is a large interpatient variation, ranging <5%-41%. The results can be applied to calibrate other practical online image-guided techniques for prostate cancer radiotherapy, when intratreatment organ motion/deformation and machine delivery accuracy are considered.
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Affiliation(s)
- Michel Ghilezan
- Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI 48073, USA
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