- Email: [email protected]
2088
S258
I. J. Radiation Oncology
● Biology ● Physics
Volume 66, Number 3, Supplement, 2006
critical structures for pelvic and head and neck sites. However, little data has been published on the use of SIB for high grade gliomas. This review presents our initial experience with SIB for the treatment of anaplastic gliomas and glioblastoma. Materials/Methods: From 1/03 to 1/06, 21 patients with high grade gliomas were treated using IMRT with SIB. 6 received gamma-knife radiosurgery to the tumor bed as part of their initial therapy and were excluded from further analysis. 11 of the remaining 15 patients had glioblastoma and 4 had anaplastic gliomas. There were 11 gross total and 3 subtotal resections; 1 patient only underwent biopsy. 10 received Temodar concurrent with radiation and 11 had further adjuvant chemotherapy upon completing radiation. Post-surgical MRIs were used for target definition. Initial planning target volume (PTV1) was T2 or enhancing flair abnormality ⫹ 2 cm and boost target volume (PTV2) was T1 enhancing abnormality ⫹ 1 cm or enhancing flair abnormality. SIB concurrently delivered 45– 46.8 Gy in 1.8 –2 Gy/fraction to PTV1 and 49 – 60 Gy in 1.9 –2.4 Gy/fraction to PTV2. 11 patients required additional IMRT boosts to bring PTV2 to 60 Gy. For a comparative analysis of dose to tumor and normal structures between SIB and non-SIB IMRT, 9 non-SIB IMRT plans were generated. BEDs for tumor were calculated using the standard linear-quadratic model and an ␣/ of 3 for tumor. Results: With a median follow-up of 22 months, 11 patients (73%) had disease progression. Median time to progression was 13 months for anaplastic gliomas and 8 months for glioblastoma. 9 (82%) recurrences were within the resection cavity or at the site of original disease. Of the patients who progressed, 7 died from disease. Median survival for the remaining 8 patients, 6 of whom had glioblastoma, was 25.5 months. SIB delivered a mean dose of 45.9 Gy (range 45– 46.8 Gy) to PTV1 and 53.2 Gy (range 49 – 60 Gy) to PTV2; sequential boosts raised the mean dose of PTV2 to 59.8 Gy (range 58.5– 61 Gy). SIB delivered ⬎2.25 Gy/fraction to PTV2 in 3 patients; 2 developed radiation necrosis at 10 and 24 months and died 27 and 22 months post-radiation and 1 is alive with no evidence of disease or necrosis 33 months post-radiation. The average treatment time was 41 days (range 36 – 45 days). Comparison of SIB and non-SIB IMRT plans showed no statistically significant difference in the mean doses of PTV1 and PTV2 or the dose delivered to the 5% and 95% target volumes. There was also no statistically significant change in dose to adjacent critical structures. Based on BED analysis, SIB delivered a mean of 3.2 Gy (range 1.2–7.5 Gy) more to the tumor bed compared to non-SIB IMRT. Conclusions: Our review suggests that SIB can effectively deliver two different fractionation schemes to different regions in a target volume without compromising tumor coverage or increasing dose to adjacent critical structures. While preliminary results are encouraging, small numbers and lack of prognostic factor analysis prevents us from drawing any definitive conclusions about survival times. Further clinical research is warranted. Author Disclosure: C.S. Hwang, None; A.E. Lujan, None; M. Gopalakrishnan, None; M.H. Marymont, None.
2088
Stereotactic Radiosurgery Alone and Primary Resection Followed by Adjuvant Stereotactic Radiosurgery in the Treatment of Limited Brain Metastases
M. Quigley, S. Karlovits, B. Karlovits, J. MacKenzie, M. Johnson, A. Colonias, R. Fuhrer Allegheny General Hospital, Pittsburgh, PA Purpose/Objective(s): Although a mainstay treatment, whole brain radiation therapy (WBRT) is frequently associated with cognitive decline, especially in long-term metastatic cancer survivors. In patients with limited brain involvement, multiple studies have shown no overall survival difference between stereotactic radiosurgery (SRS) alone and WBRT ⫹ SRS boost. We have therefore offered our patients with up to 4 intracranial metastatic lesions a therapeutic approach consisting of focused treatment employing either SRS alone or resection for accessible lesions followed by SRS to both the post-operative tumor bed plus any remaining lesions less than 3.0 cm., in all cases reserving WBRT only for salvage. Materials/Methods: Retrospective review of all patients referred to the first author with up to 4 newly diagnosed metastatic brain lesions from 7/02 - present who had not received WBRT previously. All patients were treated with 4 - 6 MV LINAC based SRS ⫹/- collimation. Results: There were 43 patients, 18 males, (mean age 61.5 years.) Primary pathology was 24 lung, 6 renal, 5 breast and 1 each of assorted others. 13 patients had multiple lesions. 17/43 patients underwent resection as initial treatment (11 solitary) with 5/17 patients having a resected lesion ⬎ 3 cm. Cone size range was 1.0 to 5 cm with mean effective cone size of 2.46 cm. Mean target volume was 2.78 mL. Median dose was 1600 cGy (range, 700 - 2000 cGy) with a median isodose of 80%. 6 patients had delayed resections for 5 in-field and 1 out-of-field recurrences. 7 patients had additional SRS for 2 in-field and 5 out-of-field recurrences. Only 5/43 (11.6%) patients received salvage WBRT, one for a twice resected recurrence and 4 with progressive diffuse new lesions. Mean survival for the entire cohort was 13.6 mos. post initial treatment. Using Cox regression model improved survival related to solitary metastasis (p⫽.04) and any resection (p⫽.0001). Among patients with solitary metastases, mean survival was significantly better in the group for which surgery was used initially 19.6 vs. 10.3 months (p⫽.035), despite 4 patients receiving rescue resections. With regard to in-field local control, lesions treated with surgery and SRS boost had a local failure rate of only 1/17 (5.8%). Conclusions: In patients with newly diagnosed limited brain metastases, resection of single accessible lesions followed by SRS to both the post-operative tumor bed plus any remaining lesions less than 3.0 cm is at least equivalent to SRS alone. Patients with solitary lesions who were treated with resection and adjuvant SRS had improved survival compared to those receiving SRS alone. Avoiding upfront WBRT in patients with resected accessible brain metastases treated with adjuvant SRS appears to be a viable treatment approach. Author Disclosure: M. Quigley, None; S. Karlovits, None; B. Karlovits, None; J. MacKenzie, None; M. Johnson, None; A. Colonias, None; R. Fuhrer, None.
I. J. Radiation Oncology
● Biology ● Physics
Volume 66, Number 3, Supplement, 2006
critical structures for pelvic and head and neck sites. However, little data has been published on the use of SIB for high grade gliomas. This review presents our initial experience with SIB for the treatment of anaplastic gliomas and glioblastoma. Materials/Methods: From 1/03 to 1/06, 21 patients with high grade gliomas were treated using IMRT with SIB. 6 received gamma-knife radiosurgery to the tumor bed as part of their initial therapy and were excluded from further analysis. 11 of the remaining 15 patients had glioblastoma and 4 had anaplastic gliomas. There were 11 gross total and 3 subtotal resections; 1 patient only underwent biopsy. 10 received Temodar concurrent with radiation and 11 had further adjuvant chemotherapy upon completing radiation. Post-surgical MRIs were used for target definition. Initial planning target volume (PTV1) was T2 or enhancing flair abnormality ⫹ 2 cm and boost target volume (PTV2) was T1 enhancing abnormality ⫹ 1 cm or enhancing flair abnormality. SIB concurrently delivered 45– 46.8 Gy in 1.8 –2 Gy/fraction to PTV1 and 49 – 60 Gy in 1.9 –2.4 Gy/fraction to PTV2. 11 patients required additional IMRT boosts to bring PTV2 to 60 Gy. For a comparative analysis of dose to tumor and normal structures between SIB and non-SIB IMRT, 9 non-SIB IMRT plans were generated. BEDs for tumor were calculated using the standard linear-quadratic model and an ␣/ of 3 for tumor. Results: With a median follow-up of 22 months, 11 patients (73%) had disease progression. Median time to progression was 13 months for anaplastic gliomas and 8 months for glioblastoma. 9 (82%) recurrences were within the resection cavity or at the site of original disease. Of the patients who progressed, 7 died from disease. Median survival for the remaining 8 patients, 6 of whom had glioblastoma, was 25.5 months. SIB delivered a mean dose of 45.9 Gy (range 45– 46.8 Gy) to PTV1 and 53.2 Gy (range 49 – 60 Gy) to PTV2; sequential boosts raised the mean dose of PTV2 to 59.8 Gy (range 58.5– 61 Gy). SIB delivered ⬎2.25 Gy/fraction to PTV2 in 3 patients; 2 developed radiation necrosis at 10 and 24 months and died 27 and 22 months post-radiation and 1 is alive with no evidence of disease or necrosis 33 months post-radiation. The average treatment time was 41 days (range 36 – 45 days). Comparison of SIB and non-SIB IMRT plans showed no statistically significant difference in the mean doses of PTV1 and PTV2 or the dose delivered to the 5% and 95% target volumes. There was also no statistically significant change in dose to adjacent critical structures. Based on BED analysis, SIB delivered a mean of 3.2 Gy (range 1.2–7.5 Gy) more to the tumor bed compared to non-SIB IMRT. Conclusions: Our review suggests that SIB can effectively deliver two different fractionation schemes to different regions in a target volume without compromising tumor coverage or increasing dose to adjacent critical structures. While preliminary results are encouraging, small numbers and lack of prognostic factor analysis prevents us from drawing any definitive conclusions about survival times. Further clinical research is warranted. Author Disclosure: C.S. Hwang, None; A.E. Lujan, None; M. Gopalakrishnan, None; M.H. Marymont, None.
2088
Stereotactic Radiosurgery Alone and Primary Resection Followed by Adjuvant Stereotactic Radiosurgery in the Treatment of Limited Brain Metastases
M. Quigley, S. Karlovits, B. Karlovits, J. MacKenzie, M. Johnson, A. Colonias, R. Fuhrer Allegheny General Hospital, Pittsburgh, PA Purpose/Objective(s): Although a mainstay treatment, whole brain radiation therapy (WBRT) is frequently associated with cognitive decline, especially in long-term metastatic cancer survivors. In patients with limited brain involvement, multiple studies have shown no overall survival difference between stereotactic radiosurgery (SRS) alone and WBRT ⫹ SRS boost. We have therefore offered our patients with up to 4 intracranial metastatic lesions a therapeutic approach consisting of focused treatment employing either SRS alone or resection for accessible lesions followed by SRS to both the post-operative tumor bed plus any remaining lesions less than 3.0 cm., in all cases reserving WBRT only for salvage. Materials/Methods: Retrospective review of all patients referred to the first author with up to 4 newly diagnosed metastatic brain lesions from 7/02 - present who had not received WBRT previously. All patients were treated with 4 - 6 MV LINAC based SRS ⫹/- collimation. Results: There were 43 patients, 18 males, (mean age 61.5 years.) Primary pathology was 24 lung, 6 renal, 5 breast and 1 each of assorted others. 13 patients had multiple lesions. 17/43 patients underwent resection as initial treatment (11 solitary) with 5/17 patients having a resected lesion ⬎ 3 cm. Cone size range was 1.0 to 5 cm with mean effective cone size of 2.46 cm. Mean target volume was 2.78 mL. Median dose was 1600 cGy (range, 700 - 2000 cGy) with a median isodose of 80%. 6 patients had delayed resections for 5 in-field and 1 out-of-field recurrences. 7 patients had additional SRS for 2 in-field and 5 out-of-field recurrences. Only 5/43 (11.6%) patients received salvage WBRT, one for a twice resected recurrence and 4 with progressive diffuse new lesions. Mean survival for the entire cohort was 13.6 mos. post initial treatment. Using Cox regression model improved survival related to solitary metastasis (p⫽.04) and any resection (p⫽.0001). Among patients with solitary metastases, mean survival was significantly better in the group for which surgery was used initially 19.6 vs. 10.3 months (p⫽.035), despite 4 patients receiving rescue resections. With regard to in-field local control, lesions treated with surgery and SRS boost had a local failure rate of only 1/17 (5.8%). Conclusions: In patients with newly diagnosed limited brain metastases, resection of single accessible lesions followed by SRS to both the post-operative tumor bed plus any remaining lesions less than 3.0 cm is at least equivalent to SRS alone. Patients with solitary lesions who were treated with resection and adjuvant SRS had improved survival compared to those receiving SRS alone. Avoiding upfront WBRT in patients with resected accessible brain metastases treated with adjuvant SRS appears to be a viable treatment approach. Author Disclosure: M. Quigley, None; S. Karlovits, None; B. Karlovits, None; J. MacKenzie, None; M. Johnson, None; A. Colonias, None; R. Fuhrer, None.