- Email: [email protected]
Late Radiation Toxicity after Conformal Radiotherapy for Prostate Cancer among Patients with Diabetes Mellitus
Proceedings of the 53rd Annual ASTRO Meeting
85
S43
Comparative Long-term Morbidity of Intensity Modulated vs. Conformal Radiation Therapy (RT) for Prostate Cancer: A SEER-Medicare Analysis
N. Sheets, G. H. Goldin, A. M. Meyer, J. D. Darter, Y. Wu, J. A. Holmes, B. B. Reeve, P. A. Godley, W. R. Carpenter, R. C. Chen University of North Carolina, Chapel Hill, NC Purpose/Objective(s): Intensity Modulated radiation therapy (IMRT) for prostate cancer has been rapidly adopted over older techniques because of its potential ability to reduce treatment-related morbidity. We examined the comparative morbidity of IMRT vs. non-IMRT using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Materials/Methods: A total of 39,662 men with non-metastatic prostate cancer diagnosed between 2000 and 2005, 66 years or older, were included. Patients with claims for any IMRT-related procedure codes were considered to have received IMRT. Patients were stratified into two cohorts for analysis: those receiving radiation (RT) only within 1 year of diagnosis (definitive RT, n = 38,159), and those receiving RT within 3 years after surgery (post-operative RT; n = 1,503). These time windows were set to minimize inclusion of palliative RT. Logistic regression models were used to examine the odds of morbidity diagnoses and procedures occurring more than 12 months after IMRT vs. non-IMRT while adjusting for year, age, race, tumor grade, SEER region, Medicaid eligibility, and education. Results: Overall, 28% of definitive RT patients and 33% of post-operative RT patients received IMRT. In the definitive RT cohort, IMRT was associated with a lower risk of non-incontinence urinary morbidity diagnoses (OR 0.91, p = 0.003), urinary incontinence diagnoses (OR 0.86, p \ 0.001) and procedures (OR 0.85, p \ 0.001), and erectile dysfunction diagnoses (OR 0.92, p = 0.02). In post-operative patients, IMRT was associated with a lower risk of GI morbidity diagnoses (OR 0.68, p = 0.03) and procedures (OR 0.62, p = 0.002). In no case was IMRT associated with increased morbidity. Conclusions: Prostate cancer patients undergoing definitive IMRT experienced lower rates of urinary morbidity and erectile dysfunction, and those undergoing post-operative IMRT had lower rates of GI morbidity. Prostatectomy is the dominant factor causing incontinence and erectile dysfunction in the post-operative patients, likely explaining the lack of difference from radiation technique. This is a large-scale study examining the comparative outcomes of IMRT vs. non-IMRT for prostate cancer, and suggests improved morbidity outcomes for IMRT in both definitive and post-operative patients. Table: Summary of multivariable analyses of morbidity outcomes for IMRT vs. non-IMRT for prostate cancer Odds ratio of IMRT vs. non-IMRT (95% CI) for definitive treatment GI morbidity Non-incontinence urinary morbidity Urinary incontinence Erectile dysfunction Hip fracture
p value
Odds ratio of IMRT vs. non-IMRT (95% CI) for post-operative treatment
p value
Diagnosis Procedure Diagnosis
1.01 (0.96 – 1.07) 1.01 (0.96 – 1.07) 0.91 (0.86 – 0.97)
0.66 0.71 0.003
0.68 (0.48 – 0.96) 0.62 (0.46 – 0.83) 0.78 (0.56 – 1.08)
0.03 0.002 0.13
Procedure Diagnosis Procedure Diagnosis Procedure Diagnosis
0.93 (0.84 – 1.03) 0.86 (0.79 – 0.94) 0.85 (0.80 – 0.91) 0.92 (0.86 – 0.99) 0.87 (0.74 – 1.03) 1.01 (0.85 – 1.21)
0.16 0.0008 \ 0.0001 0.02 0.11 0.88
1.01 (0.65 – 1.56) 1.03 (0.76 – 1.38) 0.89 (0.64 – 1.25) 0.82 (0.61 – 1.12) 0.63 (0.38 – 1.07) 1.89 (0.70 – 5.13)
0.98 0.87 0.50 0.21 0.09 0.21
Author Disclosure: N. Sheets: None. G.H. Goldin: None. A.M. Meyer: None. J.D. Darter: None. Y. Wu: None. J.A. Holmes: None. B.B. Reeve: None. P.A. Godley: None. W.R. Carpenter: None. R.C. Chen: None.
86
Late Radiation Toxicity after Conformal Radiotherapy for Prostate Cancer among Patients with Diabetes Mellitus
C. J. Novak, X. Pei, M. Kollmeier, B. Cox, M. J. Zelefsky Memorial Sloan Kettering Cancer Center, New York, NY Purpose/Objective(s): The prevalence of diabetes is increasing among prostate cancer patients, and the diabetic population may be at higher risk for late toxicity following radiation treatment. We analyzed outcomes for non-diabetic and diabetic prostate cancer patients treated with three-dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) in order to determine the impact of diabetes and treatment modality on late toxicity. Materials/Methods: Two thousand three hundred sixty-one patients with prostate cancer were treated between 1988 and 2005 with external beam radiation therapy. Eight hundred ninety-four patients received 3D-CRT and 1467 received IMRT. The median dose delivered was 81 Gy range (64.8-86.4 Gy). The median follow-up was 95 months. Radiation toxicity was graded according to the National Cancer Institute’s Common Terminology Criteria for Adverse Events. Results: When the patients were stratified by treatment modality (IMRT vs. 3D-CRT) an increased risk of rectal toxicity was observed among diabetic patients compared to non-diabetic patients. In the population treated with 3D-CRT, diabetic patients (n = 78) experienced a higher incidence of Grade 3 rectal toxicity compared to non-diabetic patients (2.6% vs. 0.4%, p = 0.06), while among patients treated with IMRT the incidence of Grade 2 and 3 rectal toxicities were similar and low for both diabetic and non-diabetic patients (Grade 2: diabetics vs. non-diabetics 1.0% vs. 2.1%; p = 0.72; Grade 3: diabetics vs. non-diabetics 0.0% vs. 0.3%; p = 1.0). The diabetic patients had a significant reduction in Grade $2 GI toxicity with the use of IMRT compared to 3D-CRT (0.9% vs. 16.7%, p \ 0.0001). On a multivariate regression analysis that included both dose and diabetic status, diabetes emerged as an independent predictor of Grade 3 rectal toxicity in the patients who received 3D-CRT (p = 0.03). In the patients who received IMRT, however, diabetic status no longer maintained significance (p = 0.96). There was no apparent increase in urinary toxicity for diabetic patients compared to non-diabetic patients treated with either 3D-CRT or IMRT.
I. J. Radiation Oncology d Biology d Physics
S44
Volume 81, Number 2, Supplement, 2011
Conclusions: Although diabetic patients were previously more susceptible to late toxicity with radiation therapy for prostate carcinoma, IMRT mitigates this risk with a significant reduction in rectal toxicity rates for these patients. In addition, in our experience the diabetic population is not prone to higher rates of urinary late toxicities compared to non-diabetics. Author Disclosure: C.J. Novak: None. X. Pei: None. M. Kollmeier: None. B. Cox: None. M.J. Zelefsky: None.
87
Preliminary Analysis of 3D-CRT vs. IMRT on the High Dose Arm of the RTOG 0126 Prostate Cancer Trial: Patient Reported Outcomes
D. Watkins Bruner1, D. Hunt2, J. M. Michalski3, W. Bosch4, Y. Yan2, J. M. Galvin5, J. Bahary6, G. C. Morton7, M. B. Parliament8, H. Sandler9 1 University of Pennsylvania School of Nursing, Philadelphia, PA, 2RTOG Statistical Center, Philadelphia, PA, 3Washington University, St Louis, MO, 4Mallinckrodt Institute of Radiology, St Louis, MO, 5Thomas Jefferson University Hospital, Philadelphia, PA, 6Centre Hospitalier de l‘Universite de Montreal-Notre Dame, Montreal, QC, Canada, 7Toronto-Sunnybrook Regional Cancer Centre, Toronto, ON, Canada, 8Cross Cancer Institute, Edmonton, AB, Canada, 9Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA
Purpose/Objective(s): It is hypothesized that IMRT is associated with less negative change in patient reported outcomes (PROs) compared to 3D-CRT. Materials/Methods: Bowel and bladder function were measured with Functional Alterations due to Changes in Elimination (FACE) and erectile function (EF) with the International Index of Erectile Function (IIEF) Questionnaire. Changes over time from 0 (baseline), to 3, 6, 12, and 24 months were evaluated. The nonparametric Wilcoxon test was used for modality comparisons. Chi-squared tests were used to compare pretreatment characteristics between patients with/without PRO data. Multivariate logistic regression analysis (MVA) was used to assess predictors of EF subscale. Results: Seven hundred sixty-three patients were randomized to the 79.2 Gy arm of RTOG 0126, a trial comparing high to standard dose RT for localized prostate cancer. 499 patients completed baseline FACE; 48%, 63%, 74%, and 66% completed FACE at 3, 6, 12, and 24 months, respectively. There were no statistically significant differences between 3D-CRT and IMRT for total FACE score or for urinary or bowel subscales at any time point. Five hundred seven patients completed baseline IIEF; of these, 56%, 65%, and 61% completed the IIEF at 6, 12, and 24 months, respectively. For total IIEF score there were no statistically significant differences at any time point. Adjusting for multiple comparisons (setting alpha = 0.01), EF and satisfaction domains of the IIEF show trends toward significance in change scores between RT modalities at 24 months (both p = 0.04), indicating less decrease in both domains for patients treated with IMRT. On MVA including RT method, age, race, time to assessment and penile bulb dose (PBD), only age (\70 years) and time to assessment (24 months) were significantly better on IMRT. Mean (SD)/median IIEF EF subscale score change for men \70 years at 24 months treated with IMRT was 2.4 (+ 7.2) and 0 points, respectively, compared to those treated with 3D-CRT which showed a change of 5.4 (+ 9.2) and 4 points. At 24 months RT method does become statistically sig. on MVA when assessing associations with the EF subscale (odds ratio, 4.3; 95% CI, 1.3 – 14.1; p = 0.02). For all patients and for patients included in this PRO analysis, percent of penile bulb receiving at least x Gy was significantly lower for IMRT compared to 3D-CRT for 40 Gy, 50 Gy, 60 Gy, and 70 Gy (all p \ 0.0001). However, in a MVA sensitivity analysis of median of each pV PBD, none were significantly associated with IIEF outcomes. Conclusions: In this study, IMRT showed no benefit over 3D-CRT related to bowel or bladder patient reported function at any time point. There was an IMRT benefit in terms of less change in EF at 24 months, especially for men younger than age 70. Acknowledgment: Supported by the Radiation Oncology Institute and RTOG U10 CA21661, CCOP U10 CA37422, and ATC U24 CA 81647 grants from the National Cancer Institute. Author Disclosure: D. Watkins Bruner: B. Research Grant; Radiation Oncology Institute and Radiation Therapy Oncology Group. D. Hunt: A. Employment; RTOG Statistician. B. Research Grant; Radiation Oncology Institute. J.M. Michalski: B. Research Grant; Radiation Oncology Institute, RTOG and ATC. W. Bosch: B. Research Grant; NCI ATC U24 CA 81647. Y. Yan: A. Employment; RTOG Statistician. B. Research Grant; Radiation Oncology Institute. J.M. Galvin: B. Research Grant; RTOG. J. Bahary: None. G.C. Morton: None. M.B. Parliament: D. Speakers Bureau/Honoraria; Sanofi-Aventis. H. Sandler: B. Research Grant; RTOG.
88
Mapping Patterns of Nodal Metastases in Seminoma: Rethinking the Para-aortic Field 1
J. Paly , J. A. Efstathiou1, S. S. Hedgire1, M. Harisinghani1, A. L. Zietman1, C. Beard2 1 Massachusetts General Hospital, Boston, MA, 2Brigham and Women’s Hospital, Boston, MA Purpose/Objective(s): Historically, radiation therapy for testicular seminoma has targeted the retroperitoneal lymph nodes (RPLN) via anterior-posterior/posterior-anterior (AP-PA) portals based upon skeletal rather than soft tissue anatomy. This study was undertaken to identify the location of involved lymph nodes and their relationship to both bony and vascular anatomy in Stage II patients. Materials/Methods: CT scans of 22 patients with Stage II seminoma diagnosed between 1996 and 2011 were independently reviewed by two readers. Forty lymph nodes were identified as radiographically positive (enlarging or .10 mm on short axis of the axial CT). Fifty-five percent of patients had left-sided primaries, 40% right-sided, and 5% bilateral disease. The position of each node in relation to the aorta, aortic bifurcation, renal hila, and vertebral bodies was recorded. Each nodal position was then transferred to a standardized CT template scan based upon its relation to skeletal and vascular anatomy. A conventional AP-PA para-aortic treatment field was overlaid on the template, covering from the top of T11 to the bottom of L5 and bounded laterally by the transverse processes. The location of involved RPLNs within the conventional AP-PA port was assessed. Results: Thirty-seven (93%) of the total positive lymph nodes were in-field with the remaining 3 in the pelvis; only 1 patient had a pelvic-only metastasis. Positive nodes congregated within the interaorto-caval, precaval, pre-aortic, paracaval and para-aortic regions between L1/L2 cranially and L5/S1 caudally. No positive nodes were identified within the renal hilar regions or superior
85
S43
Comparative Long-term Morbidity of Intensity Modulated vs. Conformal Radiation Therapy (RT) for Prostate Cancer: A SEER-Medicare Analysis
N. Sheets, G. H. Goldin, A. M. Meyer, J. D. Darter, Y. Wu, J. A. Holmes, B. B. Reeve, P. A. Godley, W. R. Carpenter, R. C. Chen University of North Carolina, Chapel Hill, NC Purpose/Objective(s): Intensity Modulated radiation therapy (IMRT) for prostate cancer has been rapidly adopted over older techniques because of its potential ability to reduce treatment-related morbidity. We examined the comparative morbidity of IMRT vs. non-IMRT using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Materials/Methods: A total of 39,662 men with non-metastatic prostate cancer diagnosed between 2000 and 2005, 66 years or older, were included. Patients with claims for any IMRT-related procedure codes were considered to have received IMRT. Patients were stratified into two cohorts for analysis: those receiving radiation (RT) only within 1 year of diagnosis (definitive RT, n = 38,159), and those receiving RT within 3 years after surgery (post-operative RT; n = 1,503). These time windows were set to minimize inclusion of palliative RT. Logistic regression models were used to examine the odds of morbidity diagnoses and procedures occurring more than 12 months after IMRT vs. non-IMRT while adjusting for year, age, race, tumor grade, SEER region, Medicaid eligibility, and education. Results: Overall, 28% of definitive RT patients and 33% of post-operative RT patients received IMRT. In the definitive RT cohort, IMRT was associated with a lower risk of non-incontinence urinary morbidity diagnoses (OR 0.91, p = 0.003), urinary incontinence diagnoses (OR 0.86, p \ 0.001) and procedures (OR 0.85, p \ 0.001), and erectile dysfunction diagnoses (OR 0.92, p = 0.02). In post-operative patients, IMRT was associated with a lower risk of GI morbidity diagnoses (OR 0.68, p = 0.03) and procedures (OR 0.62, p = 0.002). In no case was IMRT associated with increased morbidity. Conclusions: Prostate cancer patients undergoing definitive IMRT experienced lower rates of urinary morbidity and erectile dysfunction, and those undergoing post-operative IMRT had lower rates of GI morbidity. Prostatectomy is the dominant factor causing incontinence and erectile dysfunction in the post-operative patients, likely explaining the lack of difference from radiation technique. This is a large-scale study examining the comparative outcomes of IMRT vs. non-IMRT for prostate cancer, and suggests improved morbidity outcomes for IMRT in both definitive and post-operative patients. Table: Summary of multivariable analyses of morbidity outcomes for IMRT vs. non-IMRT for prostate cancer Odds ratio of IMRT vs. non-IMRT (95% CI) for definitive treatment GI morbidity Non-incontinence urinary morbidity Urinary incontinence Erectile dysfunction Hip fracture
p value
Odds ratio of IMRT vs. non-IMRT (95% CI) for post-operative treatment
p value
Diagnosis Procedure Diagnosis
1.01 (0.96 – 1.07) 1.01 (0.96 – 1.07) 0.91 (0.86 – 0.97)
0.66 0.71 0.003
0.68 (0.48 – 0.96) 0.62 (0.46 – 0.83) 0.78 (0.56 – 1.08)
0.03 0.002 0.13
Procedure Diagnosis Procedure Diagnosis Procedure Diagnosis
0.93 (0.84 – 1.03) 0.86 (0.79 – 0.94) 0.85 (0.80 – 0.91) 0.92 (0.86 – 0.99) 0.87 (0.74 – 1.03) 1.01 (0.85 – 1.21)
0.16 0.0008 \ 0.0001 0.02 0.11 0.88
1.01 (0.65 – 1.56) 1.03 (0.76 – 1.38) 0.89 (0.64 – 1.25) 0.82 (0.61 – 1.12) 0.63 (0.38 – 1.07) 1.89 (0.70 – 5.13)
0.98 0.87 0.50 0.21 0.09 0.21
Author Disclosure: N. Sheets: None. G.H. Goldin: None. A.M. Meyer: None. J.D. Darter: None. Y. Wu: None. J.A. Holmes: None. B.B. Reeve: None. P.A. Godley: None. W.R. Carpenter: None. R.C. Chen: None.
86
Late Radiation Toxicity after Conformal Radiotherapy for Prostate Cancer among Patients with Diabetes Mellitus
C. J. Novak, X. Pei, M. Kollmeier, B. Cox, M. J. Zelefsky Memorial Sloan Kettering Cancer Center, New York, NY Purpose/Objective(s): The prevalence of diabetes is increasing among prostate cancer patients, and the diabetic population may be at higher risk for late toxicity following radiation treatment. We analyzed outcomes for non-diabetic and diabetic prostate cancer patients treated with three-dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) in order to determine the impact of diabetes and treatment modality on late toxicity. Materials/Methods: Two thousand three hundred sixty-one patients with prostate cancer were treated between 1988 and 2005 with external beam radiation therapy. Eight hundred ninety-four patients received 3D-CRT and 1467 received IMRT. The median dose delivered was 81 Gy range (64.8-86.4 Gy). The median follow-up was 95 months. Radiation toxicity was graded according to the National Cancer Institute’s Common Terminology Criteria for Adverse Events. Results: When the patients were stratified by treatment modality (IMRT vs. 3D-CRT) an increased risk of rectal toxicity was observed among diabetic patients compared to non-diabetic patients. In the population treated with 3D-CRT, diabetic patients (n = 78) experienced a higher incidence of Grade 3 rectal toxicity compared to non-diabetic patients (2.6% vs. 0.4%, p = 0.06), while among patients treated with IMRT the incidence of Grade 2 and 3 rectal toxicities were similar and low for both diabetic and non-diabetic patients (Grade 2: diabetics vs. non-diabetics 1.0% vs. 2.1%; p = 0.72; Grade 3: diabetics vs. non-diabetics 0.0% vs. 0.3%; p = 1.0). The diabetic patients had a significant reduction in Grade $2 GI toxicity with the use of IMRT compared to 3D-CRT (0.9% vs. 16.7%, p \ 0.0001). On a multivariate regression analysis that included both dose and diabetic status, diabetes emerged as an independent predictor of Grade 3 rectal toxicity in the patients who received 3D-CRT (p = 0.03). In the patients who received IMRT, however, diabetic status no longer maintained significance (p = 0.96). There was no apparent increase in urinary toxicity for diabetic patients compared to non-diabetic patients treated with either 3D-CRT or IMRT.
I. J. Radiation Oncology d Biology d Physics
S44
Volume 81, Number 2, Supplement, 2011
Conclusions: Although diabetic patients were previously more susceptible to late toxicity with radiation therapy for prostate carcinoma, IMRT mitigates this risk with a significant reduction in rectal toxicity rates for these patients. In addition, in our experience the diabetic population is not prone to higher rates of urinary late toxicities compared to non-diabetics. Author Disclosure: C.J. Novak: None. X. Pei: None. M. Kollmeier: None. B. Cox: None. M.J. Zelefsky: None.
87
Preliminary Analysis of 3D-CRT vs. IMRT on the High Dose Arm of the RTOG 0126 Prostate Cancer Trial: Patient Reported Outcomes
D. Watkins Bruner1, D. Hunt2, J. M. Michalski3, W. Bosch4, Y. Yan2, J. M. Galvin5, J. Bahary6, G. C. Morton7, M. B. Parliament8, H. Sandler9 1 University of Pennsylvania School of Nursing, Philadelphia, PA, 2RTOG Statistical Center, Philadelphia, PA, 3Washington University, St Louis, MO, 4Mallinckrodt Institute of Radiology, St Louis, MO, 5Thomas Jefferson University Hospital, Philadelphia, PA, 6Centre Hospitalier de l‘Universite de Montreal-Notre Dame, Montreal, QC, Canada, 7Toronto-Sunnybrook Regional Cancer Centre, Toronto, ON, Canada, 8Cross Cancer Institute, Edmonton, AB, Canada, 9Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA
Purpose/Objective(s): It is hypothesized that IMRT is associated with less negative change in patient reported outcomes (PROs) compared to 3D-CRT. Materials/Methods: Bowel and bladder function were measured with Functional Alterations due to Changes in Elimination (FACE) and erectile function (EF) with the International Index of Erectile Function (IIEF) Questionnaire. Changes over time from 0 (baseline), to 3, 6, 12, and 24 months were evaluated. The nonparametric Wilcoxon test was used for modality comparisons. Chi-squared tests were used to compare pretreatment characteristics between patients with/without PRO data. Multivariate logistic regression analysis (MVA) was used to assess predictors of EF subscale. Results: Seven hundred sixty-three patients were randomized to the 79.2 Gy arm of RTOG 0126, a trial comparing high to standard dose RT for localized prostate cancer. 499 patients completed baseline FACE; 48%, 63%, 74%, and 66% completed FACE at 3, 6, 12, and 24 months, respectively. There were no statistically significant differences between 3D-CRT and IMRT for total FACE score or for urinary or bowel subscales at any time point. Five hundred seven patients completed baseline IIEF; of these, 56%, 65%, and 61% completed the IIEF at 6, 12, and 24 months, respectively. For total IIEF score there were no statistically significant differences at any time point. Adjusting for multiple comparisons (setting alpha = 0.01), EF and satisfaction domains of the IIEF show trends toward significance in change scores between RT modalities at 24 months (both p = 0.04), indicating less decrease in both domains for patients treated with IMRT. On MVA including RT method, age, race, time to assessment and penile bulb dose (PBD), only age (\70 years) and time to assessment (24 months) were significantly better on IMRT. Mean (SD)/median IIEF EF subscale score change for men \70 years at 24 months treated with IMRT was 2.4 (+ 7.2) and 0 points, respectively, compared to those treated with 3D-CRT which showed a change of 5.4 (+ 9.2) and 4 points. At 24 months RT method does become statistically sig. on MVA when assessing associations with the EF subscale (odds ratio, 4.3; 95% CI, 1.3 – 14.1; p = 0.02). For all patients and for patients included in this PRO analysis, percent of penile bulb receiving at least x Gy was significantly lower for IMRT compared to 3D-CRT for 40 Gy, 50 Gy, 60 Gy, and 70 Gy (all p \ 0.0001). However, in a MVA sensitivity analysis of median of each pV PBD, none were significantly associated with IIEF outcomes. Conclusions: In this study, IMRT showed no benefit over 3D-CRT related to bowel or bladder patient reported function at any time point. There was an IMRT benefit in terms of less change in EF at 24 months, especially for men younger than age 70. Acknowledgment: Supported by the Radiation Oncology Institute and RTOG U10 CA21661, CCOP U10 CA37422, and ATC U24 CA 81647 grants from the National Cancer Institute. Author Disclosure: D. Watkins Bruner: B. Research Grant; Radiation Oncology Institute and Radiation Therapy Oncology Group. D. Hunt: A. Employment; RTOG Statistician. B. Research Grant; Radiation Oncology Institute. J.M. Michalski: B. Research Grant; Radiation Oncology Institute, RTOG and ATC. W. Bosch: B. Research Grant; NCI ATC U24 CA 81647. Y. Yan: A. Employment; RTOG Statistician. B. Research Grant; Radiation Oncology Institute. J.M. Galvin: B. Research Grant; RTOG. J. Bahary: None. G.C. Morton: None. M.B. Parliament: D. Speakers Bureau/Honoraria; Sanofi-Aventis. H. Sandler: B. Research Grant; RTOG.
88
Mapping Patterns of Nodal Metastases in Seminoma: Rethinking the Para-aortic Field 1
J. Paly , J. A. Efstathiou1, S. S. Hedgire1, M. Harisinghani1, A. L. Zietman1, C. Beard2 1 Massachusetts General Hospital, Boston, MA, 2Brigham and Women’s Hospital, Boston, MA Purpose/Objective(s): Historically, radiation therapy for testicular seminoma has targeted the retroperitoneal lymph nodes (RPLN) via anterior-posterior/posterior-anterior (AP-PA) portals based upon skeletal rather than soft tissue anatomy. This study was undertaken to identify the location of involved lymph nodes and their relationship to both bony and vascular anatomy in Stage II patients. Materials/Methods: CT scans of 22 patients with Stage II seminoma diagnosed between 1996 and 2011 were independently reviewed by two readers. Forty lymph nodes were identified as radiographically positive (enlarging or .10 mm on short axis of the axial CT). Fifty-five percent of patients had left-sided primaries, 40% right-sided, and 5% bilateral disease. The position of each node in relation to the aorta, aortic bifurcation, renal hila, and vertebral bodies was recorded. Each nodal position was then transferred to a standardized CT template scan based upon its relation to skeletal and vascular anatomy. A conventional AP-PA para-aortic treatment field was overlaid on the template, covering from the top of T11 to the bottom of L5 and bounded laterally by the transverse processes. The location of involved RPLNs within the conventional AP-PA port was assessed. Results: Thirty-seven (93%) of the total positive lymph nodes were in-field with the remaining 3 in the pelvis; only 1 patient had a pelvic-only metastasis. Positive nodes congregated within the interaorto-caval, precaval, pre-aortic, paracaval and para-aortic regions between L1/L2 cranially and L5/S1 caudally. No positive nodes were identified within the renal hilar regions or superior