2897
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3D radiosensitivity maps, structure contours, and beamlets from a commercial planning system (Xio, CMS) as inputs, a developed MATLAB package optimizes beamlet weights based on a sequential quadratic programming (SQP) method to achieve maximum equivalent uniform dose (EUD) for target. The EUD was calculated based on 3D-dose and spatial radiosensitivity distributions. Constraints that limit the doses to critical structures not to exceed the corresponding maxima from a reference conventional plan with uniform target dose are applied. Results: Using the newly developed system, we have generated non-uniform 3D-dose distributions for selected patient cases. Depending on the variation of the voxel radiosensitivity, the sub-regional dose escalation can be as high as 30% of the uniform dose as planned conventionally. This is illustrated with dose volume histogram (DVH) comparison in Figure 1. While the EUDs for organs at risk are approximately equal to or lower than those for the uniform dose plans, the target EUDs are found to be higher. Conclusions: We have developed an inverse planning methodology/package that is capable of generating IMRT plans with non-uniform dose distributions. We have demonstrated that the non-uniform dose plans for malignant glioma can take into account the spatially inhomogeneous radiosensitivity extracted from physiological MRI. Sub-regional dose escalation may lead to increased treatment effectiveness as indicated by EUDs. The current development has the potential to improve biological image guided radiotherapy. Author Disclosure: G. Chen, None; E. Ahunbay, None; C. Schultz, None; X.A. Li, None. 2897 Local Control of Extremity Myxoid Liposarcoma. P. W. M. Chung 1,2 , A. M. Griffin 3 , J. S. Wunder 2,3 , C. N. Catton 1,2 , P. C. Ferguson 2,3 , R. S. Bell 1,2 , L. M. White 2,3 , R. Kandel 2,3 , B. O’Sullivan 1,2 1 Princess Margaret Hospital, Toronto, ON, Canada, 2 University of Toronto, Toronto, ON, Canada, 3 Mount Sinai Hospital, Toronto, ON, Canada Purpose/Objective(s): Myxoid liposarcoma is unusual compared to other soft tissue sarcomas in that it is uniquely radiosen- sitive and this has prompted us to assess if this translates into improved local control when radiotherapy (RT) is used in the management. These tumours also have a predilection for non-pulmonary metastases that may be unpredictable and occur late. We report our experience of patients treated for myxoid liposarcoma of the extremity at a multidisciplinary sarcoma centre with focus on the local control of cases managed with RT. Materials/Methods: We identified 112 patients treated for extremity myxoid liposarcoma between 1989 and 2004 from our prospectively collected institutional database. Two patients were excluded from analysis (metastatic disease at presentation). All patients had pathology review to confirm diagnosis. Patients were managed with limb sparing surgery where possible. Radiotherapy was used in patients with deep tumors where wide margins would have been prohibitive for limb sparing, ‘unplanned’ excisions with gross residual tumor or microscopic positive margins. When given, RT dose was 50Gy pre- operatively and 60 – 66Gy post-operatively. Adjuvant chemotherapy was not given. Local control was defined as absence of clinical or imaging evidence of disease. No patients have been lost to follow up (median 71 months, range 17–171). Results: Of 110 patients with localized disease, 80% had tumors located in the lower extremity. Two patients required a primary amputation, 42 patients had prior ‘unplanned’ excision elsewhere, of whom, 19 patients had positive margins on re-excision. Median tumor size was 8cm (2–36cm); 17 patients had grade 1, 80 grade 2 and 13 had grade 3 tumors. Preoperative RT was employed in 50 patients, postoperative RT in 38 and 22 mostly superficial cases received no RT. Local recurrence developed in 3 patients (2.7%), who all had positive margins. Of these, 2 had received RT and the other did not (due to contraindication to RT). Of 12 patients who developed metastases (all had grade 2/3 tumors), 5 had pulmonary and 7 non-pulmonary metastases (4-soft tissue, 2-bone, 1-lymph nodes). Ninety-four patients (85%) are currently alive without disease, 6 are alive with disease, 7 are dead of disease and 3 have died of other causes. Conclusions: Myxoid liposarcoma of the extremity has a high rate of extra-pulmonary recurrence. Excellent local control rates can be achieved with wide surgical margins when obtainable, however, in advanced presentations where it seems particularly indicated, radiotherapy in addition to limb sparing surgery provides equally good results. Author Disclosure: P.W.M. Chung, None; A.M. Griffin, None; J.S. Wunder, None; C.N. Catton, None; P.C. Ferguson, None; R.S. Bell, None; L.M. White, None; R. Kandel, None; B. O’Sullivan, None. 2898 National Surgical Patterns of Care: Axillary Staging of Breast Sarcomas N. Poynter, K. Delman, A. L. Folpe, P. A. Johnstone Emory University School of Medicine, Atlanta, GA Background: Soft tissue sarcomas [STS] of the breast are rare tumors; therefore little data are available regarding their management. Standard surgical treatment of STS does not include sampling of regional lymph nodes (LNs). Purpose/Objective(s): We hypothesized that the management of breast STS may present a unique situation: given their experience with the more common epithelial lesions of the breast, surgeons may be more prone to sample LNs in these patients than would otherwise be indicated based on histologic subtype. We reviewed national surgical patterns of care for axillary LN sampling for breast STS using the Surveillance Epidemiology & End Results (SEER) registry. Materials/Methods: SEER data for LN examination are available from 1988. The public-access SEER registry was queried for patients presenting between 1988 and 2002 with STS of the breast. Data were collated by number of LNs examined, and further analyzed by histology, grade and tumor size of the primary lesion where available. To allow for 5-year relative survival (5YRS) calculations, 210 patients from 1988 –1998 were analyzed. Results: 333 cases of STS were identified for the 15-year period. 294 patients had specific surgical procedures reported: 4 subcutaneous, 98 simple, 99 modified radical, 3 radical and 90 partial mastectomies were performed. The remainder of cases S718 I. J. Radiation Oncology ● Biology ● Physics Volume 66, Number 3, Supplement, 2006
Transcript of 2897
3D radiosensitivity maps, structure contours, and beamlets from a commercial planning system (Xio, CMS) as inputs, adeveloped MATLAB package optimizes beamlet weights based on a sequential quadratic programming (SQP) method toachieve maximum equivalent uniform dose (EUD) for target. The EUD was calculated based on 3D-dose and spatialradiosensitivity distributions. Constraints that limit the doses to critical structures not to exceed the corresponding maxima froma reference conventional plan with uniform target dose are applied.
Results: Using the newly developed system, we have generated non-uniform 3D-dose distributions for selected patient cases.Depending on the variation of the voxel radiosensitivity, the sub-regional dose escalation can be as high as 30% of the uniformdose as planned conventionally. This is illustrated with dose volume histogram (DVH) comparison in Figure 1. While the EUDsfor organs at risk are approximately equal to or lower than those for the uniform dose plans, the target EUDs are found to behigher.
Conclusions: We have developed an inverse planning methodology/package that is capable of generating IMRT plans withnon-uniform dose distributions. We have demonstrated that the non-uniform dose plans for malignant glioma can take intoaccount the spatially inhomogeneous radiosensitivity extracted from physiological MRI. Sub-regional dose escalation may leadto increased treatment effectiveness as indicated by EUDs. The current development has the potential to improve biologicalimage guided radiotherapy.
Author Disclosure: G. Chen, None; E. Ahunbay, None; C. Schultz, None; X.A. Li, None.
2897 Local Control of Extremity Myxoid Liposarcoma.
P. W. M. Chung1,2, A. M. Griffin3, J. S. Wunder2,3, C. N. Catton1,2, P. C. Ferguson2,3, R. S. Bell1,2, L. M. White2,3,R. Kandel2,3, B. O’Sullivan1,2
1Princess Margaret Hospital, Toronto, ON, Canada, 2University of Toronto, Toronto, ON, Canada, 3Mount Sinai Hospital,Toronto, ON, Canada
Purpose/Objective(s): Myxoid liposarcoma is unusual compared to other soft tissue sarcomas in that it is uniquely radiosen-sitive and this has prompted us to assess if this translates into improved local control when radiotherapy (RT) is used in themanagement. These tumours also have a predilection for non-pulmonary metastases that may be unpredictable and occur late.We report our experience of patients treated for myxoid liposarcoma of the extremity at a multidisciplinary sarcoma centre withfocus on the local control of cases managed with RT.
Materials/Methods: We identified 112 patients treated for extremity myxoid liposarcoma between 1989 and 2004 from ourprospectively collected institutional database. Two patients were excluded from analysis (metastatic disease at presentation). Allpatients had pathology review to confirm diagnosis. Patients were managed with limb sparing surgery where possible.Radiotherapy was used in patients with deep tumors where wide margins would have been prohibitive for limb sparing,‘unplanned’ excisions with gross residual tumor or microscopic positive margins. When given, RT dose was 50Gy pre-operatively and 60–66Gy post-operatively. Adjuvant chemotherapy was not given. Local control was defined as absence ofclinical or imaging evidence of disease. No patients have been lost to follow up (median 71 months, range 17–171).
Results: Of 110 patients with localized disease, 80% had tumors located in the lower extremity. Two patients required a primaryamputation, 42 patients had prior ‘unplanned’ excision elsewhere, of whom, 19 patients had positive margins on re-excision.Median tumor size was 8cm (2–36cm); 17 patients had grade 1, 80 grade 2 and 13 had grade 3 tumors. Preoperative RT wasemployed in 50 patients, postoperative RT in 38 and 22 mostly superficial cases received no RT. Local recurrence developedin 3 patients (2.7%), who all had positive margins. Of these, 2 had received RT and the other did not (due to contraindicationto RT). Of 12 patients who developed metastases (all had grade 2/3 tumors), 5 had pulmonary and 7 non-pulmonary metastases(4-soft tissue, 2-bone, 1-lymph nodes). Ninety-four patients (85%) are currently alive without disease, 6 are alive with disease,7 are dead of disease and 3 have died of other causes.
Conclusions: Myxoid liposarcoma of the extremity has a high rate of extra-pulmonary recurrence. Excellent local control ratescan be achieved with wide surgical margins when obtainable, however, in advanced presentations where it seems particularlyindicated, radiotherapy in addition to limb sparing surgery provides equally good results.
Author Disclosure: P.W.M. Chung, None; A.M. Griffin, None; J.S. Wunder, None; C.N. Catton, None; P.C. Ferguson, None;R.S. Bell, None; L.M. White, None; R. Kandel, None; B. O’Sullivan, None.
2898 National Surgical Patterns of Care: Axillary Staging of Breast Sarcomas
N. Poynter, K. Delman, A. L. Folpe, P. A. Johnstone
Emory University School of Medicine, Atlanta, GA
Background: Soft tissue sarcomas [STS] of the breast are rare tumors; therefore little data are available regarding theirmanagement. Standard surgical treatment of STS does not include sampling of regional lymph nodes (LNs).
Purpose/Objective(s): We hypothesized that the management of breast STS may present a unique situation: given theirexperience with the more common epithelial lesions of the breast, surgeons may be more prone to sample LNs in these patientsthan would otherwise be indicated based on histologic subtype. We reviewed national surgical patterns of care for axillary LNsampling for breast STS using the Surveillance Epidemiology & End Results (SEER) registry.
Materials/Methods: SEER data for LN examination are available from 1988. The public-access SEER registry was queriedfor patients presenting between 1988 and 2002 with STS of the breast. Data were collated by number of LNs examined, andfurther analyzed by histology, grade and tumor size of the primary lesion where available. To allow for 5-year relative survival(5YRS) calculations, 210 patients from 1988–1998 were analyzed.
Results: 333 cases of STS were identified for the 15-year period. 294 patients had specific surgical procedures reported: 4subcutaneous, 98 simple, 99 modified radical, 3 radical and 90 partial mastectomies were performed. The remainder of cases
S718 I. J. Radiation Oncology ● Biology ● Physics Volume 66, Number 3, Supplement, 2006
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