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The Impact of Diabetes Mellitus on Survival in Men with Clinically Localized Prostate Cancer Treated with Permanent Interstitial Brachytherapy
I. J. Radiation Oncology d Biology d Physics
S366
2362
Volume 78, Number 3, Supplement, 2010
The Impact of Prostate Outlining Inaccuracies on Reported Quality Metrics for Prostate Seed Brachytherapy
B. Mzenda, A. Palmer, O. Hayman Portsmouth Hospitals NHS Trust, Portsmouth, United Kingdom Purpose/Objective(s): A steep learning curve is often experienced when developing a prostate brachytherapy seed implantation technique and it is essential to assess the quality of each implant using a robust method with an appreciation of the typical errors involved. This study investigates the accuracy requirements for prostate outlining and seed localization on post-implant CT, and their affect on quality measures, using a simulation model and a clinical study involving multiple observers. Materials/Methods: Part 1: An analytical model was used to simulate inaccuracies in both outlining and seed localization and determine the effect on reported V100, V150, and D90. New outlines were drawn on post-implant CT data with linear dimensions varied by between 5 and 20% in steps of 5%, using uniform and non-uniform modifications. The incremental outlines represent errors in contouring the prostate volume. The resulting DVHs were used to quantify the effect on the dosimetric parameters of the volume changes. Random errors in seed locations were also introduced, with shifts of between 1 and 10mm, to evaluate positional affects of seed identification, quantifying the variation in resulting dosimetry quality. Part 2: Inter- and intra-observer variations in prostate outlining were assessed using post-implant CT for 30 patients and 5 observers, and interpreted alongside the accuracy requirements determined in Part 1. Results: Part 1: Typical dosimetric parameter errors for specified outlining inaccuracy were determined: e.g. if outlining is accurate to within 8mm (10% change of 35cc volume) at the central slice, then average percentage confidences (1s.d.) are 3.5% for D90, 2.0% for V100. While variations in seed position affect local isodose distributions, the total effect of multiple random variations had little impact on overall dosimetric quality. Part 2: Inter-observer variations in outlining resulted in differences of up to 4.2% for D90 and 2.5% for V100. Intra-observer variations led to smaller changes. Conclusions: The required accuracy of seed location and prostate outlining in post-implant CT for reliable dosimetric quality assessment has been demonstrated. The operator-dependent variations are typically within the magnitude of the accuracy requirements determined from the analytical model. Even with the limitations of prostate visibility on CT, this approach to post implant dosimetry is a valid and reliable method to assessing the quality of seed implants. Author Disclosure: B. Mzenda, None; A. Palmer, None; O. Hayman, None.
2363
The Impact of Diabetes Mellitus on Survival in Men with Clinically Localized Prostate Cancer Treated with Permanent Interstitial Brachytherapy
A. Torlone1, G. S. Merrick2, W. M. Butler2, R. W. Butler2, K. E. Wallner3, E. Adamovich4 1
Schiffler Cancer Center, Wheeling, WV, 2Schiffler Cancer Center/Wheeling Jesuit University, Wheeling, WV, 3Puget Sound Healthcare Corporation, Seattle, WA, 4Wheeling Hospital, Dept of Pathology, Wheeling, WV Purpose/Objective(s): In general, patients with cancer of any kind with pre-existing diabetes are at increased risk for long-term, all-cause mortality compared to those without diabetes. However, the influence of diabetes on biochemical progression free survival (bPFS), cause specific survival (CSS) and overall survival (OS) has not been clearly defined following brachytherapy for clinically localized prostate cancer. Materials/Methods: From April 1995 - June 2006, 1,624 consecutive patients underwent permanent interstitial brachytherapy. A pre-brachytherapy diagnosis of diabetes was present in 199 patients (12.3%). Median follow-up was 7.8 years. Of the patients, 812 (50%) received supplemental external beam radiation therapy and 627 (38.0%) received androgen deprivation therapy (ADT). The median day 0 D90 was 118.7% of prescription dose. Cause of death was determined for each deceased patient. Patients with metastatic prostate cancer or castrate resistant disease without obvious metastases who died of any cause were classified as dead of prostate cancer. All other deaths were attributed to the immediate cause of death. Multiple clinical, treatment and dosimetric parameters were evaluated to determine the effect of diabetes on survival. Results: Patients with diabetes were statistically older (66.6 vs. 65.1 years, p = 0.010), more likely to be obese (BMI 29.8 vs. 27.3, p \ 0.001), hypertensive (73.9% vs. 45.9%, p \ 0.001) and have hypercholesterolemia (44.7% vs. 28.3%, p \ 0.001) and/or coronary artery disease (23.1% vs. 15.9%, p = 0.009). In patients without and with diabetes mellitus, CSS was 97.2% vs. 100%, bPFS was 95.6% vs. 95.7% and overall survival was 74.3% vs. 54.9%. In Cox regression analysis, OS in non-diabetic patients was most closely related to patient age, coronary artery disease, tobacco consumption and ADT. In diabetic patients, OS was related to patient age and coronary artery disease with a strong trend for tobacco. bPFS was most closely related to percent positive biopsies and clinical stage in patients without diabetes and with percent positive biopsies and pre-treatment PSA in diabetic patients. In patients without diabetes, CSS was most closely associated with Gleason score and clinical stage. No patient with diabetes died of prostate cancer. Patients with diabetes mellitus were more likely to die of cardiovascular disease (10.6% vs. 6.9%) and were more likely to die of non-prostate cancers (7.5% vs. 5.1%). Conclusions: Diabetes mellitus does not impact CSS or bPFS following brachytherapy. However, OS is significantly less in diabetic patients as a result of increased risk of death from cardiovascular disease and non-prostate cancers. Author Disclosure: A. Torlone, None; G.S. Merrick, None; W.M. Butler, None; R.W. Butler, None; K.E. Wallner, None; E. Adamovich, None.
2364
Five-year Clinical Outcome in Intermediate Risk Gleason 7 Cancer Patients Treated with Image-guided Adaptive Radiation Therapy vs. Image-guided Brachytherapy as Monotherapy
M. Wallace1, M. Ghilezan1, C. Mitchell2, L. Kestin1, C. Shah1, K. Marvin1, D. Brabbins1, G. Gustafson2, H. Ye1, A. Martinez1 1
William Beaumont Hospital, Royal Oak, MI, 2William Beaumont Hospital, Troy, MI
S366
2362
Volume 78, Number 3, Supplement, 2010
The Impact of Prostate Outlining Inaccuracies on Reported Quality Metrics for Prostate Seed Brachytherapy
B. Mzenda, A. Palmer, O. Hayman Portsmouth Hospitals NHS Trust, Portsmouth, United Kingdom Purpose/Objective(s): A steep learning curve is often experienced when developing a prostate brachytherapy seed implantation technique and it is essential to assess the quality of each implant using a robust method with an appreciation of the typical errors involved. This study investigates the accuracy requirements for prostate outlining and seed localization on post-implant CT, and their affect on quality measures, using a simulation model and a clinical study involving multiple observers. Materials/Methods: Part 1: An analytical model was used to simulate inaccuracies in both outlining and seed localization and determine the effect on reported V100, V150, and D90. New outlines were drawn on post-implant CT data with linear dimensions varied by between 5 and 20% in steps of 5%, using uniform and non-uniform modifications. The incremental outlines represent errors in contouring the prostate volume. The resulting DVHs were used to quantify the effect on the dosimetric parameters of the volume changes. Random errors in seed locations were also introduced, with shifts of between 1 and 10mm, to evaluate positional affects of seed identification, quantifying the variation in resulting dosimetry quality. Part 2: Inter- and intra-observer variations in prostate outlining were assessed using post-implant CT for 30 patients and 5 observers, and interpreted alongside the accuracy requirements determined in Part 1. Results: Part 1: Typical dosimetric parameter errors for specified outlining inaccuracy were determined: e.g. if outlining is accurate to within 8mm (10% change of 35cc volume) at the central slice, then average percentage confidences (1s.d.) are 3.5% for D90, 2.0% for V100. While variations in seed position affect local isodose distributions, the total effect of multiple random variations had little impact on overall dosimetric quality. Part 2: Inter-observer variations in outlining resulted in differences of up to 4.2% for D90 and 2.5% for V100. Intra-observer variations led to smaller changes. Conclusions: The required accuracy of seed location and prostate outlining in post-implant CT for reliable dosimetric quality assessment has been demonstrated. The operator-dependent variations are typically within the magnitude of the accuracy requirements determined from the analytical model. Even with the limitations of prostate visibility on CT, this approach to post implant dosimetry is a valid and reliable method to assessing the quality of seed implants. Author Disclosure: B. Mzenda, None; A. Palmer, None; O. Hayman, None.
2363
The Impact of Diabetes Mellitus on Survival in Men with Clinically Localized Prostate Cancer Treated with Permanent Interstitial Brachytherapy
A. Torlone1, G. S. Merrick2, W. M. Butler2, R. W. Butler2, K. E. Wallner3, E. Adamovich4 1
Schiffler Cancer Center, Wheeling, WV, 2Schiffler Cancer Center/Wheeling Jesuit University, Wheeling, WV, 3Puget Sound Healthcare Corporation, Seattle, WA, 4Wheeling Hospital, Dept of Pathology, Wheeling, WV Purpose/Objective(s): In general, patients with cancer of any kind with pre-existing diabetes are at increased risk for long-term, all-cause mortality compared to those without diabetes. However, the influence of diabetes on biochemical progression free survival (bPFS), cause specific survival (CSS) and overall survival (OS) has not been clearly defined following brachytherapy for clinically localized prostate cancer. Materials/Methods: From April 1995 - June 2006, 1,624 consecutive patients underwent permanent interstitial brachytherapy. A pre-brachytherapy diagnosis of diabetes was present in 199 patients (12.3%). Median follow-up was 7.8 years. Of the patients, 812 (50%) received supplemental external beam radiation therapy and 627 (38.0%) received androgen deprivation therapy (ADT). The median day 0 D90 was 118.7% of prescription dose. Cause of death was determined for each deceased patient. Patients with metastatic prostate cancer or castrate resistant disease without obvious metastases who died of any cause were classified as dead of prostate cancer. All other deaths were attributed to the immediate cause of death. Multiple clinical, treatment and dosimetric parameters were evaluated to determine the effect of diabetes on survival. Results: Patients with diabetes were statistically older (66.6 vs. 65.1 years, p = 0.010), more likely to be obese (BMI 29.8 vs. 27.3, p \ 0.001), hypertensive (73.9% vs. 45.9%, p \ 0.001) and have hypercholesterolemia (44.7% vs. 28.3%, p \ 0.001) and/or coronary artery disease (23.1% vs. 15.9%, p = 0.009). In patients without and with diabetes mellitus, CSS was 97.2% vs. 100%, bPFS was 95.6% vs. 95.7% and overall survival was 74.3% vs. 54.9%. In Cox regression analysis, OS in non-diabetic patients was most closely related to patient age, coronary artery disease, tobacco consumption and ADT. In diabetic patients, OS was related to patient age and coronary artery disease with a strong trend for tobacco. bPFS was most closely related to percent positive biopsies and clinical stage in patients without diabetes and with percent positive biopsies and pre-treatment PSA in diabetic patients. In patients without diabetes, CSS was most closely associated with Gleason score and clinical stage. No patient with diabetes died of prostate cancer. Patients with diabetes mellitus were more likely to die of cardiovascular disease (10.6% vs. 6.9%) and were more likely to die of non-prostate cancers (7.5% vs. 5.1%). Conclusions: Diabetes mellitus does not impact CSS or bPFS following brachytherapy. However, OS is significantly less in diabetic patients as a result of increased risk of death from cardiovascular disease and non-prostate cancers. Author Disclosure: A. Torlone, None; G.S. Merrick, None; W.M. Butler, None; R.W. Butler, None; K.E. Wallner, None; E. Adamovich, None.
2364
Five-year Clinical Outcome in Intermediate Risk Gleason 7 Cancer Patients Treated with Image-guided Adaptive Radiation Therapy vs. Image-guided Brachytherapy as Monotherapy
M. Wallace1, M. Ghilezan1, C. Mitchell2, L. Kestin1, C. Shah1, K. Marvin1, D. Brabbins1, G. Gustafson2, H. Ye1, A. Martinez1 1
William Beaumont Hospital, Royal Oak, MI, 2William Beaumont Hospital, Troy, MI