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Outcomes and Toxicities of Stereotactic Body Radiation Therapy (SBRT) for Nonspine Osseous Oligometastases
S724
International Journal of Radiation Oncology Biology Physics
conformality number (CN) and heterogeneity index (HI) of the target was determined for each plan, and two tail student paired t-test was used to compare differences in the mean for each parameter. The importance of tumor factors (volume, location), patient factors (FEV1 or Functional Expiratory Volume in 1 second, body mass index) and treatment factors (number of SBRT beams) on the dose distributions obtained from the two algorithms, were statistically determined using linear regression analyses. Results: No difference to mean target dose was observed for the plans from either algorithm. However, in comparison to AAA, a small and significant difference in dose distribution (p < 0.00001) to the target was found for the Acuros XB algorithm, resulting in lower conformity (-2.1%, p < 0.00001) and higher heterogeneity of dose. Single logistic regression identified FEV1, number of beams and target location as having a strong correlation with the difference of CN between the two calculations. Multivariable analysis indicated that FEV1 (p Z 0.0296) was the only predictor for the difference seen in the two dose calculation algorithms. Conclusions: Although no difference in mean target dose was identified between Acuros XB and AAA; there is a small, but significant difference in target dose distribution. This leads to differences in target dose conformality and heterogeneity for this cohort of patients. The patients’ lung function, which leads to changes in the lung density, correlates with the degree of difference in conformality between the two dose calculation algorithms. The reason for this difference is secondary to the accurate modeling of tissue by the Acuros XB algorithm. The current study supports that the Acuros XB algorithm is a more suitable tool for dose calculation in patients with poor pulmonary function, than the convolution based algorithm. Author Disclosure: R. Clayton: None. H. Liu: None. H. Lau: None. P. Dunscombe: None. Z. Nugent: None. R. Khan: None.
3363
3362 Outcomes and Toxicities of Stereotactic Body Radiation Therapy (SBRT) for Nonspine Osseous Oligometastases D. Owen,1 N.N. Laack,1 C. Mayo,1 Y.I. Garces,1 S. Park,1 H.J. Bauer,1 K. Nelson,1 R.W. Miller,1 P.D. Brown,2 and K.R. Olivier1; 1Mayo Clinic, Rochester, MN, 2University of Texas MD Anderson Cancer Centre, Houston, TX Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) is being applied more widely for oligometastatic disease. This technique is now being used on non-spine bony metastases in addition to liver, spine, and lung. However, there are few studies examining the toxicity and outcomes of SBRT for non-spine osseous metastases. Materials/Methods: Between 2008 and 2012, 74 subjects with oligometastatic non-spine osseous metastases of varying histologies were treated at the Mayo Clinic with SBRT. A total of 85 non-spine osseous sites were treated. Median local control, overall survival, and progression free survival were described. Acute toxicity (defined as toxicity < 90 days) and late toxicity (defined as toxicity 90 days) were reported and graded as per standardized CTCAE 4.0 criteria. Results: The median age of patients treated was 60 years. The most common histology was prostate cancer (31%) and most patients had fewer than 3 sites of disease at the time of simulation (64%). Most of the non-spine osseous sites lay within the pelvis (65%). Dose and fractionation varied but the most common prescription was 24 Gy/1 fraction. Local recurrence occurred in 7 patients with a median time to failure of 2.8 months. Local control was 91.8% at 1 year. With a median follow-up of 7.6 months, median SBRT specific overall survival and progression free survival were 9.3 months and 9.7 months respectively. 18 patients developed acute toxicity (mostly grade 1 and 2 fatigue and acute pain flare). 9 patients developed grade 1-2 late toxicities. Two patients developed pathologic fractures but both were asymptomatic. There were no late grade 3 or 4 toxicities. Conclusions: SBRT is a feasible and tolerable treatment for non-spine bony metastases. Longer follow-up will be needed to accurately determine late effects. Author Disclosure: D. Owen: None. N.N. Laack: None. C. Mayo: None. Y.I. Garces: None. S. Park: None. H.J. Bauer: None. K. Nelson: None. R.W. Miller: None. P.D. Brown: None. K.R. Olivier: None.
Spine SBRT Plans: Achieving Dose Coverage, Conformity, and Dose Fall-Off L. Hong,1 S. Viswanathan,2 J. Shen,1 H. Kuo,1 D. Mynampati,1 R. Yaparpalvi,1 M. Garg,1 J. Fox,1 S. Kalnicki,1 and W.A. Tome1,2; 1 Montefiore Medical Center, Bronx, NY, 2Albert Einstein College of Medicine, Bronx, NY Purpose/Objective(s): In this study, we report our experiences in establishing planning objectives to achieve dose coverage, conformity and dose fall off for spine SBRT plans. Materials/Methods: Patients with spine lesions were treated using SBRT technique in our center since 9/2009. All patients were treated with IMRT fields or VMAT arcs either on Varian Trilogy or Truebeam. Plans were done with TPS. However, since 9/2011, we established our planning objectives based on RTOG 0631 spine and 0915 lung SBRT protocols in addition to cord dose constraints: 1) Dose coverage: Prescription Dose (PD) to cover at least 95% PTV volume (PTV V100%PD 95%) and 99% PD to cover at least 99% PTV (PTV V90%PD 99%); 2) Conformity Index (CI): ratio of prescription isodose volume to the PTV volume < 1.2; 3) Dose Fall Off: ratio of 50% prescription isodose volume to the PTV volume (R50%) and maximum dose in % of PD at 2 cm from PTV in any direction (D2cm) should follow RTOG 0915 Table. We retrospectively reviewed a total of 66 separate spine lesions treated between 9/2009 to 12/ 2012 with either single fraction dose of at least 16 Gy (8 lesions) or with a fractional dose of 8 Gy for a total of 3 fractions (57 lesions). Thirty-one (2 Cspine, 20 Tspine and 9 Lspine) lesions were treated before 9/2011 (Group 1) and 35 (1 Cspine, 23 Tspine and 11 Lspine) lesions were treated after (Group 2). These plans were evaluated on the dose coverage, conformity and Dose Fall Off. Descriptive statistics were computed, Chisquare test was used to examine difference in parameters between groups. Results: The median PTV volume was 25 cc (range, 8 to 194) and 26 cc (range, 6 to 205) for Groups 1 and 2 respectively. PTV V100%PD 95% objective was met in 29.0% of Group 1 vs 91.4% of Group 2 plans and the difference was statistically significant (p < 0.0001). Mean (SD) PTV V100%PD was 89.5 7.9 and 96.8 2.1 for Group 1 and Group 2, respectively. The number of plans met PTV V90%PD 99% objective was 38.7% for Group 1 vs 88.6% for Group 2 and the difference was statistically significant (p < 0.0001). Mean (SD) CI was 1.05 0.28 for Group 1 and 1.07 0.06 for Group 2. 4 plans in Group 1 had CI > 1.2 vs all plans in Group 2 had CI < 1.2, and the difference was statistically significant (p Z 0.04). For R50%, 29.0% plans had minor violation of the objectives and 16.1% had major violation for Group 1, while 25.7% had minor violation and 5.7% had major violation for Group 2. The difference was not statistically significant (p Z 0.15). For D2cm, 48.3% plans had minor violation of the objectives and 16.1% had major violation for Group 1, while 17.1% had minor violation and 2.9% had major violation for Group 2. The difference was statistically significant (p Z 0.0004). Conclusions: Spine SBRT plans can be improved on dose coverage, conformity and dose fall off by utilizing planning objectives based on RTOG spine and lung SBRT protocols. Author Disclosure: L. Hong: None. S. Viswanathan: None. J. Shen: None. H. Kuo: None. D. Mynampati: None. R. Yaparpalvi: None. M. Garg: None. J. Fox: None. S. Kalnicki: None. W.A. Tome: None.
3364 WITHDRAWN
3365 Stereotactic Body Radiation Therapy (SBRT) With Flattening FilterFree (FFF) Mode for Treatment of Lung Metastases in Oligometastatic Patients P. Navarria, A. Ascolese, F. Alongi, S. Tomatis, P. Mancosu, A. Tozzi, T. Comito, E. Clerici, E. Villa, and M. Scorsetti; Istituto Clinico Humanitas Cancer Center, Milano, Italy
International Journal of Radiation Oncology Biology Physics
conformality number (CN) and heterogeneity index (HI) of the target was determined for each plan, and two tail student paired t-test was used to compare differences in the mean for each parameter. The importance of tumor factors (volume, location), patient factors (FEV1 or Functional Expiratory Volume in 1 second, body mass index) and treatment factors (number of SBRT beams) on the dose distributions obtained from the two algorithms, were statistically determined using linear regression analyses. Results: No difference to mean target dose was observed for the plans from either algorithm. However, in comparison to AAA, a small and significant difference in dose distribution (p < 0.00001) to the target was found for the Acuros XB algorithm, resulting in lower conformity (-2.1%, p < 0.00001) and higher heterogeneity of dose. Single logistic regression identified FEV1, number of beams and target location as having a strong correlation with the difference of CN between the two calculations. Multivariable analysis indicated that FEV1 (p Z 0.0296) was the only predictor for the difference seen in the two dose calculation algorithms. Conclusions: Although no difference in mean target dose was identified between Acuros XB and AAA; there is a small, but significant difference in target dose distribution. This leads to differences in target dose conformality and heterogeneity for this cohort of patients. The patients’ lung function, which leads to changes in the lung density, correlates with the degree of difference in conformality between the two dose calculation algorithms. The reason for this difference is secondary to the accurate modeling of tissue by the Acuros XB algorithm. The current study supports that the Acuros XB algorithm is a more suitable tool for dose calculation in patients with poor pulmonary function, than the convolution based algorithm. Author Disclosure: R. Clayton: None. H. Liu: None. H. Lau: None. P. Dunscombe: None. Z. Nugent: None. R. Khan: None.
3363
3362 Outcomes and Toxicities of Stereotactic Body Radiation Therapy (SBRT) for Nonspine Osseous Oligometastases D. Owen,1 N.N. Laack,1 C. Mayo,1 Y.I. Garces,1 S. Park,1 H.J. Bauer,1 K. Nelson,1 R.W. Miller,1 P.D. Brown,2 and K.R. Olivier1; 1Mayo Clinic, Rochester, MN, 2University of Texas MD Anderson Cancer Centre, Houston, TX Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) is being applied more widely for oligometastatic disease. This technique is now being used on non-spine bony metastases in addition to liver, spine, and lung. However, there are few studies examining the toxicity and outcomes of SBRT for non-spine osseous metastases. Materials/Methods: Between 2008 and 2012, 74 subjects with oligometastatic non-spine osseous metastases of varying histologies were treated at the Mayo Clinic with SBRT. A total of 85 non-spine osseous sites were treated. Median local control, overall survival, and progression free survival were described. Acute toxicity (defined as toxicity < 90 days) and late toxicity (defined as toxicity 90 days) were reported and graded as per standardized CTCAE 4.0 criteria. Results: The median age of patients treated was 60 years. The most common histology was prostate cancer (31%) and most patients had fewer than 3 sites of disease at the time of simulation (64%). Most of the non-spine osseous sites lay within the pelvis (65%). Dose and fractionation varied but the most common prescription was 24 Gy/1 fraction. Local recurrence occurred in 7 patients with a median time to failure of 2.8 months. Local control was 91.8% at 1 year. With a median follow-up of 7.6 months, median SBRT specific overall survival and progression free survival were 9.3 months and 9.7 months respectively. 18 patients developed acute toxicity (mostly grade 1 and 2 fatigue and acute pain flare). 9 patients developed grade 1-2 late toxicities. Two patients developed pathologic fractures but both were asymptomatic. There were no late grade 3 or 4 toxicities. Conclusions: SBRT is a feasible and tolerable treatment for non-spine bony metastases. Longer follow-up will be needed to accurately determine late effects. Author Disclosure: D. Owen: None. N.N. Laack: None. C. Mayo: None. Y.I. Garces: None. S. Park: None. H.J. Bauer: None. K. Nelson: None. R.W. Miller: None. P.D. Brown: None. K.R. Olivier: None.
Spine SBRT Plans: Achieving Dose Coverage, Conformity, and Dose Fall-Off L. Hong,1 S. Viswanathan,2 J. Shen,1 H. Kuo,1 D. Mynampati,1 R. Yaparpalvi,1 M. Garg,1 J. Fox,1 S. Kalnicki,1 and W.A. Tome1,2; 1 Montefiore Medical Center, Bronx, NY, 2Albert Einstein College of Medicine, Bronx, NY Purpose/Objective(s): In this study, we report our experiences in establishing planning objectives to achieve dose coverage, conformity and dose fall off for spine SBRT plans. Materials/Methods: Patients with spine lesions were treated using SBRT technique in our center since 9/2009. All patients were treated with IMRT fields or VMAT arcs either on Varian Trilogy or Truebeam. Plans were done with TPS. However, since 9/2011, we established our planning objectives based on RTOG 0631 spine and 0915 lung SBRT protocols in addition to cord dose constraints: 1) Dose coverage: Prescription Dose (PD) to cover at least 95% PTV volume (PTV V100%PD 95%) and 99% PD to cover at least 99% PTV (PTV V90%PD 99%); 2) Conformity Index (CI): ratio of prescription isodose volume to the PTV volume < 1.2; 3) Dose Fall Off: ratio of 50% prescription isodose volume to the PTV volume (R50%) and maximum dose in % of PD at 2 cm from PTV in any direction (D2cm) should follow RTOG 0915 Table. We retrospectively reviewed a total of 66 separate spine lesions treated between 9/2009 to 12/ 2012 with either single fraction dose of at least 16 Gy (8 lesions) or with a fractional dose of 8 Gy for a total of 3 fractions (57 lesions). Thirty-one (2 Cspine, 20 Tspine and 9 Lspine) lesions were treated before 9/2011 (Group 1) and 35 (1 Cspine, 23 Tspine and 11 Lspine) lesions were treated after (Group 2). These plans were evaluated on the dose coverage, conformity and Dose Fall Off. Descriptive statistics were computed, Chisquare test was used to examine difference in parameters between groups. Results: The median PTV volume was 25 cc (range, 8 to 194) and 26 cc (range, 6 to 205) for Groups 1 and 2 respectively. PTV V100%PD 95% objective was met in 29.0% of Group 1 vs 91.4% of Group 2 plans and the difference was statistically significant (p < 0.0001). Mean (SD) PTV V100%PD was 89.5 7.9 and 96.8 2.1 for Group 1 and Group 2, respectively. The number of plans met PTV V90%PD 99% objective was 38.7% for Group 1 vs 88.6% for Group 2 and the difference was statistically significant (p < 0.0001). Mean (SD) CI was 1.05 0.28 for Group 1 and 1.07 0.06 for Group 2. 4 plans in Group 1 had CI > 1.2 vs all plans in Group 2 had CI < 1.2, and the difference was statistically significant (p Z 0.04). For R50%, 29.0% plans had minor violation of the objectives and 16.1% had major violation for Group 1, while 25.7% had minor violation and 5.7% had major violation for Group 2. The difference was not statistically significant (p Z 0.15). For D2cm, 48.3% plans had minor violation of the objectives and 16.1% had major violation for Group 1, while 17.1% had minor violation and 2.9% had major violation for Group 2. The difference was statistically significant (p Z 0.0004). Conclusions: Spine SBRT plans can be improved on dose coverage, conformity and dose fall off by utilizing planning objectives based on RTOG spine and lung SBRT protocols. Author Disclosure: L. Hong: None. S. Viswanathan: None. J. Shen: None. H. Kuo: None. D. Mynampati: None. R. Yaparpalvi: None. M. Garg: None. J. Fox: None. S. Kalnicki: None. W.A. Tome: None.
3364 WITHDRAWN
3365 Stereotactic Body Radiation Therapy (SBRT) With Flattening FilterFree (FFF) Mode for Treatment of Lung Metastases in Oligometastatic Patients P. Navarria, A. Ascolese, F. Alongi, S. Tomatis, P. Mancosu, A. Tozzi, T. Comito, E. Clerici, E. Villa, and M. Scorsetti; Istituto Clinico Humanitas Cancer Center, Milano, Italy