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Dosimetric consequences to the pelvic lymph nodes due to the daily motion of the prostate
Proceedings of the 46th Annual ASTRO Meeting
rectal or urinary complications. The 3-year actuarial likelihood of ?Grade 2 late rectal or urinary toxicity was 0%. The 4-year actuarial PSA relapse-free survival rates for intermediate and unfavourable risk group patients were 96 and 91 % respectively. Conclusions: The data presented demonstrate the feasibility of high-dose 3D-EBRT⫹HDR brachytherapy as a safe and effective method of escalating the dose to the prostate without increasing the risk of late effects. Acute as well as late rectal and urinary complications seems to be significantly reduced, compared with what has been observed with high-dose conventional, 3D-conformal or IMRT. Short-term PSA control rates seem to be at least comparable to those achieved with 3D-EBRT or IMRT. The value of dose escalation by brachytherapy to disease control must wait for longer follow-up. Based on this preliminary results it is justified to continue including patients in the High-dose 3D-EBRT⫹HDR brachytherapy protocol.
2238
Dosimetric Consequences to the Pelvic Lymph Nodes Due to the Daily Motion of the Prostate
1
H. Chen, P. Xia,1 L. Verhey,1 M. RoachIII1 Radiation Oncology, UCSF, San Francisco, CA
1
Purpose/Objective: A link between the lymph node coverage in prostate patients and their progression-free survival is indicated in RTOG 9413[1]. It is therefore of clinical importance to have a quantitative understanding of the dose to the lymph nodes by various treatment approaches. At UCSF, setup errors and the daily motion of the prostate are corrected by tracking 3 gold markers implanted into the prostate. Because the daily changes in the position of the prostate are largely independent of the locations of the lymph nodes, changes in dose to the lymph nodes due to the prostate motion can be significant especially in the IMRT treatment setting where the dose gradient between different structures can be steep. The objective of this study is therefore to determine the dosimetric consequences to the lymph nodes resulting from the daily adjustments of the position of the prostate using IMRT and the traditional 4-field-box techniques. Materials/Methods: Ten patients were selected for this study. The position of the prostate is used to adjust the center of the treatment fields daily. These patients received the whole-pelvis (WP) irradiation by either the IMRT or the conventional 4-field-box methods. A single set of CT images taken prior to the course of treatment was used in creating treatment plans for each patient. If a patient received the IMRT WP treatment, a corresponding set of 4-field treatment plans based on the movements of the prostate was generated. Similarly, a set of IMRT plans was produced if a patient received the 4-field-box irradiation. All plans were created using the commercial Pinnacle 6.2 treatment planning system by Philips. The same PTV, defined as CTV plus 5mm tumor margin, was used in the generation of all treatment plans. The DVHs of relevant structures were analyzed for each patient and conclusions drawn by comparing the results for all ten patients. Results: Preliminary results show that in the 4-field-box treatment setting, the lymph-node volume that received over 45Gy could decrease by as mush as 10% when the isocenter was shifted by 10mm anteriorly or inferiorly. The largest increase in the small-bowel volume that received over 45Gy occurred in the 10mm anterior move where the percentage increase was approximately 65% and the absolute increase about 72cc. In the IMRT plans, the most pronounced decrease in the lymph-node volume that received over 45Gy was in the superior direction. In this case, reductions of approximately 11% and 26% were seen when the isocenter was moved by 5mm and 10mm, respectively. In the IMRT treatment mode, an average of 6% reduction in the lymph-node volume that received over 45Gy was noted with a 5mm move of the prostate, and an average of 17% reduction was found with a 10mm shift. Averages were obtained by giving equal weight to the movements in all directions. Also noteworthy is the significant decrease in the prostate and seminal-vesicle volumes that received over 45Gy (ranging from 5% to 50%) by the IMRT method. Although the percentage increase in the small-bowel volume that received over 45Gy could be large (up to 400%), the absolute volume was negligibly small (⬍ 2% of total) due to the high conformality of the IMRT plans. Conclusions: Movement of the entire pelvic field according to the prostate motion has a significant impact on the coverage of the lymph nodes and the planned DVHs of surrounding normal tissues. The degree of impact depends on the magnitude of the movement and the margins used for the relevant structures. For patients with large (⬎10mm) prostate movements in the anterior direction, the small bowel doses increased substantially while the coverage of the presacral nodes was compromised. Conversely, large posterior moves put the external iliac nodes at risk for being under-treated. For the IMRT plans, our preliminary results suggest that the prostate motion could cause serious under-dosage of the lymph nodes. Reference: Mack Roach III, M.D. and Michelle DeSilvio, Ph.D., Whole-Pelvis vs. Mini-Pelvis vs. PO in Patients Undergoing Neoadjuvant Hormonal Therapy on RTOG 9413: Secondary Analysis, February 2004.
2239
Feasibility of RNA Collection for Micro-Array Gene Expression Analysis in the Treatment of Cervical Carcinoma: A Scientific Correlate of RTOG C-0128
D. K. Gaffney,1,5 K. Winter,3 C. Fuhrman,5 R. Flinner,6 K. Greven,4 J. Ryu,10 A. Forbes,7 K. Kerlin,9 R. C. Nichols,8 Z. Karen2,5 1 Radiation Oncology, University of Utah, Salt Lake City, UT, 2Obstetrics and Gynecology, University of Utah, Salt Lake City, UT, 3Statistics, RTOG, Philadelphia, PA, 4Radiation Oncology, Wake Forest University, Winston-Salem, NC, 5 Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, 6Pathology, LDS Hospital, Salt Lake City, UT, 7 Radiation Oncology, MD Anderson, Orlando, FL, 8Radiaton Oncology, Gulf Coast Cancer Treatment Center, Panama City, FL, 9Radiation Oncology, Wayne Radiation Oncology, Greensboro, NC, 10Radiation Oncology, University of California-Davis, Sacramento, CA Purpose/Objective: To determine the feasibility of RNA collection in a multi-institutional cooperative group setting to be utilized for micro-array gene expression analysis, and to describe the methodology. Materials/Methods: RTOG C0128, a phase I-II, protocol was designed to look at the safety and efficacy of external beam radiation therapy to 45 Gy with concomitant 5-FU and cisplatin chemotherapy, brachytherapy to deliver 85 Gy to point A, and Celecoxib at 400 mg twice daily for one year. Patients had the option of participating in a tissue collection portion of the protocol to be utilized for micro-array gene expression analysis. Fresh tissue was placed immediately into RNA Later solution,
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rectal or urinary complications. The 3-year actuarial likelihood of ?Grade 2 late rectal or urinary toxicity was 0%. The 4-year actuarial PSA relapse-free survival rates for intermediate and unfavourable risk group patients were 96 and 91 % respectively. Conclusions: The data presented demonstrate the feasibility of high-dose 3D-EBRT⫹HDR brachytherapy as a safe and effective method of escalating the dose to the prostate without increasing the risk of late effects. Acute as well as late rectal and urinary complications seems to be significantly reduced, compared with what has been observed with high-dose conventional, 3D-conformal or IMRT. Short-term PSA control rates seem to be at least comparable to those achieved with 3D-EBRT or IMRT. The value of dose escalation by brachytherapy to disease control must wait for longer follow-up. Based on this preliminary results it is justified to continue including patients in the High-dose 3D-EBRT⫹HDR brachytherapy protocol.
2238
Dosimetric Consequences to the Pelvic Lymph Nodes Due to the Daily Motion of the Prostate
1
H. Chen, P. Xia,1 L. Verhey,1 M. RoachIII1 Radiation Oncology, UCSF, San Francisco, CA
1
Purpose/Objective: A link between the lymph node coverage in prostate patients and their progression-free survival is indicated in RTOG 9413[1]. It is therefore of clinical importance to have a quantitative understanding of the dose to the lymph nodes by various treatment approaches. At UCSF, setup errors and the daily motion of the prostate are corrected by tracking 3 gold markers implanted into the prostate. Because the daily changes in the position of the prostate are largely independent of the locations of the lymph nodes, changes in dose to the lymph nodes due to the prostate motion can be significant especially in the IMRT treatment setting where the dose gradient between different structures can be steep. The objective of this study is therefore to determine the dosimetric consequences to the lymph nodes resulting from the daily adjustments of the position of the prostate using IMRT and the traditional 4-field-box techniques. Materials/Methods: Ten patients were selected for this study. The position of the prostate is used to adjust the center of the treatment fields daily. These patients received the whole-pelvis (WP) irradiation by either the IMRT or the conventional 4-field-box methods. A single set of CT images taken prior to the course of treatment was used in creating treatment plans for each patient. If a patient received the IMRT WP treatment, a corresponding set of 4-field treatment plans based on the movements of the prostate was generated. Similarly, a set of IMRT plans was produced if a patient received the 4-field-box irradiation. All plans were created using the commercial Pinnacle 6.2 treatment planning system by Philips. The same PTV, defined as CTV plus 5mm tumor margin, was used in the generation of all treatment plans. The DVHs of relevant structures were analyzed for each patient and conclusions drawn by comparing the results for all ten patients. Results: Preliminary results show that in the 4-field-box treatment setting, the lymph-node volume that received over 45Gy could decrease by as mush as 10% when the isocenter was shifted by 10mm anteriorly or inferiorly. The largest increase in the small-bowel volume that received over 45Gy occurred in the 10mm anterior move where the percentage increase was approximately 65% and the absolute increase about 72cc. In the IMRT plans, the most pronounced decrease in the lymph-node volume that received over 45Gy was in the superior direction. In this case, reductions of approximately 11% and 26% were seen when the isocenter was moved by 5mm and 10mm, respectively. In the IMRT treatment mode, an average of 6% reduction in the lymph-node volume that received over 45Gy was noted with a 5mm move of the prostate, and an average of 17% reduction was found with a 10mm shift. Averages were obtained by giving equal weight to the movements in all directions. Also noteworthy is the significant decrease in the prostate and seminal-vesicle volumes that received over 45Gy (ranging from 5% to 50%) by the IMRT method. Although the percentage increase in the small-bowel volume that received over 45Gy could be large (up to 400%), the absolute volume was negligibly small (⬍ 2% of total) due to the high conformality of the IMRT plans. Conclusions: Movement of the entire pelvic field according to the prostate motion has a significant impact on the coverage of the lymph nodes and the planned DVHs of surrounding normal tissues. The degree of impact depends on the magnitude of the movement and the margins used for the relevant structures. For patients with large (⬎10mm) prostate movements in the anterior direction, the small bowel doses increased substantially while the coverage of the presacral nodes was compromised. Conversely, large posterior moves put the external iliac nodes at risk for being under-treated. For the IMRT plans, our preliminary results suggest that the prostate motion could cause serious under-dosage of the lymph nodes. Reference: Mack Roach III, M.D. and Michelle DeSilvio, Ph.D., Whole-Pelvis vs. Mini-Pelvis vs. PO in Patients Undergoing Neoadjuvant Hormonal Therapy on RTOG 9413: Secondary Analysis, February 2004.
2239
Feasibility of RNA Collection for Micro-Array Gene Expression Analysis in the Treatment of Cervical Carcinoma: A Scientific Correlate of RTOG C-0128
D. K. Gaffney,1,5 K. Winter,3 C. Fuhrman,5 R. Flinner,6 K. Greven,4 J. Ryu,10 A. Forbes,7 K. Kerlin,9 R. C. Nichols,8 Z. Karen2,5 1 Radiation Oncology, University of Utah, Salt Lake City, UT, 2Obstetrics and Gynecology, University of Utah, Salt Lake City, UT, 3Statistics, RTOG, Philadelphia, PA, 4Radiation Oncology, Wake Forest University, Winston-Salem, NC, 5 Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, 6Pathology, LDS Hospital, Salt Lake City, UT, 7 Radiation Oncology, MD Anderson, Orlando, FL, 8Radiaton Oncology, Gulf Coast Cancer Treatment Center, Panama City, FL, 9Radiation Oncology, Wayne Radiation Oncology, Greensboro, NC, 10Radiation Oncology, University of California-Davis, Sacramento, CA Purpose/Objective: To determine the feasibility of RNA collection in a multi-institutional cooperative group setting to be utilized for micro-array gene expression analysis, and to describe the methodology. Materials/Methods: RTOG C0128, a phase I-II, protocol was designed to look at the safety and efficacy of external beam radiation therapy to 45 Gy with concomitant 5-FU and cisplatin chemotherapy, brachytherapy to deliver 85 Gy to point A, and Celecoxib at 400 mg twice daily for one year. Patients had the option of participating in a tissue collection portion of the protocol to be utilized for micro-array gene expression analysis. Fresh tissue was placed immediately into RNA Later solution,
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