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Intraoperative Radiation Therapy (IORT) for Ductal Carcinoma In Situ (DCIS): A Single Institution Study
Poster Viewing Abstracts S257
Volume 84 Number 3S Supplement 2012
2101 Intraoperative Radiation Therapy (IORT) for Ductal Carcinoma In Situ (DCIS): A Single Institution Study A. Rashtian,1 Y.R. Zhang,1 H.R. Macdonald,1 S.F. Sener,1 M.P. Korah,2 S.Y. Zhou,1 and D.R. Holmes3; 1University of Southern California, Los Angeles, CA, 2University of Southern California, Marina del Ray, CA, 3 California Hospital Medical Center, Los Angeles, CA Purpose/Objective(s): The majority of local recurrences for DCIS after breast conservation therapy occur within the lumpectomy cavity. Thus, giving radiation to the tumor bed only may be adequate for selected patients. Published data from the TARGIT trial have shown that IORT is effective in treating select early stage invasive breast cancer with shortterm follow up. We reviewed our single institution experience with the use of IORT after lumpectomy for patients with DCIS of the breast. Materials/Methods: Between 2006 and 2011, 23 patients with pure DCIS of the breast were treated with lumpectomy and IORT to 5 Gy at 1.0 cm from applicator surface. The size of the DCIS ranged from 0.2 cm to 3.6 cm. The range in age at diagnosis was 45-79 years old. Eleven patients (49%) had high-grade tumors and eight (35%) had comedonecrosis. Margins were negative in all patients and ranged from 0.28 cm to >1.0 cm. Hormone receptor status was known for all patients with 17 (74%) having ER+ disease. Actuarial local control was calculated using the KaplanMeier method. Results: The median follow-up was 18.3 months. The 3-year actuarial local control rate was 93.3%. One recurrence was noted 12 months after IORT in close proximity to tumor bed. This patients was 49 years old at diagnosis and had a 1.2 cm DCIS, grade 3, with solid and cribriform pattern, ER/PR+, and a 0.5 cm closest superior margin. She did not receive endocrine therapy. Conclusion: For selected patients with DCIS, IORT is a feasible treatment option and may be considered as an alternative to conventional whole breast radiation and/or other forms of partial breast radiation. Longer follow-up is needed to prove that this treatment technique offers equal efficacy when compared to the gold standard of whole breast radiation. Author Disclosure: A. Rashtian: None. Y.R. Zhang: None. H.R. Macdonald: None. S.F. Sener: None. M.P. Korah: None. S.Y. Zhou: None. D.R. Holmes: None.
2102 Cardiac Sparing With Breath-hold Technique: A Dosimetric Evaluation of Benefits in Different Patient Populations A. Lin, D. Kim, W. Sharieff, J. Szabo, J. Sussman, I. Dayes, B. Strang, J. Wright, H. Reiter, and T. Whelan; Juravinski Cancer Centre, Hamilton, ON, Canada Purpose/Objective(s): This study aims to evaluate the reduction of cardiac radiation exposure with deep inspiration breath hold (DIBH) technique compared to free breathing (FB) in patients with left-sided breast cancer. The study also aims to evaluate whether the benefits of DIBH vary in patients who had whole breast radiation therapy (RT) after breast conserving therapy (BCT) and those who had chest wall RT postmastectomy (PM). Materials/Methods: FB and DIBH plans were generated for 17 serial PM patients and 15 BCT patients who underwent RT with DIBH using RPM system in 2011. Cardiac shields were used in all BCT plans, provided that clinical treatment volume coverage (i.e. seroma + 1cm) was not compromised, while chest wall coverage took priority in PM plans. The prescribed dose was 50 Gy in 25 fractions for the whole breast or the chest wall. Parameters of interest were cardiac V5, mean LAD dose, maximum LAD dose, and average cardiac dose. The changes in cardiac doses from FB to DIBH were compared in BCT and PM patients using paired t-tests. In order to gauge clinically meaningful outcome, the proportion of patients with V5 < 5% and mean cardiac dose < 2 Gy were compared using McNemar’s test between DIBH and FB subgroups. Results: DIBH decreased V5 (7% vs. 2%; p < 0.001) by a relative reduction of 71.4% in PM group, by 61.1% (3.6% vs. 1.4%; p Z 0.007) in
BCT group. DIBH reduced the mean heart dose by 45.7% (234 cGy vs. 127 cGy; p < 0.001) in PM group, and by 40.3% (139 cGy vs. 84 cGy; p Z 0.001) in BCT group. DIBH reduced mean LAD by 64.2% (1872 cGy vs. 671 cGy; p < 0.001) in PM group, and by 62.5% (1150 cGy vs. 431 cGy; p < 0.001) in BCT group. DIBH also reduced max LAD dose by 30.9% (4020 cGy vs. 2776 cGy; p Z 0.001) in PM group, and by 47.7% (3730 cGy vs. 1952 cGy; p Z 0.001) in BCT group. In BCT group, cardiac V5<5% were achieved in 10/15 (67%) FB patients, and in 15/15 (100%) DIBH patients (p Z 0.002), and average cardiac dose < 2 Gy were achieved in 12/15 (80%) FB patients and in 15/15 (100%) DIBH patients (p < 0.001). This compares with PM group, in which V5<5% were achieved in 6/17 (35%) FB patients and in 16/17 (94%) DIBH patients (p Z 0.05), and average cardiac dose <2 Gy were achieved in 7/17 FB (41%) an 16/17 DIBH patients (94%) (p Z 0.03). Conclusion: The results of this study suggest that there is considerable reduction in cardiac exposure in most patients with DIBH compared to FB. However, dosimetric gains in some BCT cases are small, which may be translatable to only minor measurable clinical benefits. The use of cardiac shields and collimators/ gantry adjustments, more readily applicable for BCT cases, may limit the benefits of DIBH. In an environment where DIBH availability is limited, the result of this study supports the preferential use of DIBH in PM patients over BCT patients. Author Disclosure: A. Lin: None. D. Kim: None. W. Sharieff: None. J. Szabo: None. J. Sussman: None. I. Dayes: None. B. Strang: None. J. Wright: None. H. Reiter: None. T. Whelan: None.
2103 CTV Boost Margin for Adjuvant Breast Radiation Therapy d Results of a Study Comparing US Versus CT Imaging M.G. Sattler and J. Pignol; University of Toronto at Sunnybrook Health Sciences Centre, Toronto, ON, Canada Purpose/Objective(s): A clinical target volume (CTV) boost margin of 10 mm is recommended around the seroma based upon the data from the anatomical distribution of microscopic tumor foci surrounding the primary breast tumor reported in mastectomy and re-lumpectomy specimen studies. For boost delivery and partial breast irradiation, the seroma is defined on Computed Tomography (CT) scan images. On CT, the high-density seroma can include the fluid-filled cavity, but may also include postoperative architectural distortion, breast tissue stranding, fibrosis, adjacent retroareolar tissue, and normal dense breast parenchyma. The purpose of this study is to compare seroma volumes using CT versus US imaging methods and to estimate how much CTV margin expansion corresponds to the volume increase seen on CT. Materials/Methods: As part of a prospective trial of partial breast brachytherapy using a permanent breast seed implant (PBSI) a cohort of patients have been assessed for eligibility using CT simulation and a breast US to identify the seroma. The seroma volume was calculated and the largest orthogonal X (medial-lateral), Y (anterior-posterior) and Z (superior-inferior) diameters were measured on both imaging modalities. A nomogram estimating the volume based on the largest orthogonal X, Y and Z diameters (V Z X*Y*Z*C, with C a normalization constant) was created and were evaluated by comparing the volumes calculated by the Pinnacle planning system and derived from the nomogram. The volumes derived from both imaging modalities were compared with Paired t-tests and the radial expansion between the CT and US seroma volume was calculated assuming that both would be spherical volumes. Results: A total of 183 patients were screened for PBSI between December 2004 and March 2012 and included in this study. A constant of C Z 0.486 fits the volumes best calculated by the treatment planning system and those derived using the orthogonal 3D diameters. The nomogram enables evaluating the seroma volume from the 3D diameters (correlation coefficient r Z 0.975, p < 0.001). Volumes calculated for US were about 4.4 times smaller compared to CT (p < 0.001), with the average volume measured of 3.6 cc and 15 cc for US and CT respectively. The volume excess seen on the CT image would correspond to a median expansion larger than 2.5 mm for 90% of the patients and larger than 5 mm
Volume 84 Number 3S Supplement 2012
2101 Intraoperative Radiation Therapy (IORT) for Ductal Carcinoma In Situ (DCIS): A Single Institution Study A. Rashtian,1 Y.R. Zhang,1 H.R. Macdonald,1 S.F. Sener,1 M.P. Korah,2 S.Y. Zhou,1 and D.R. Holmes3; 1University of Southern California, Los Angeles, CA, 2University of Southern California, Marina del Ray, CA, 3 California Hospital Medical Center, Los Angeles, CA Purpose/Objective(s): The majority of local recurrences for DCIS after breast conservation therapy occur within the lumpectomy cavity. Thus, giving radiation to the tumor bed only may be adequate for selected patients. Published data from the TARGIT trial have shown that IORT is effective in treating select early stage invasive breast cancer with shortterm follow up. We reviewed our single institution experience with the use of IORT after lumpectomy for patients with DCIS of the breast. Materials/Methods: Between 2006 and 2011, 23 patients with pure DCIS of the breast were treated with lumpectomy and IORT to 5 Gy at 1.0 cm from applicator surface. The size of the DCIS ranged from 0.2 cm to 3.6 cm. The range in age at diagnosis was 45-79 years old. Eleven patients (49%) had high-grade tumors and eight (35%) had comedonecrosis. Margins were negative in all patients and ranged from 0.28 cm to >1.0 cm. Hormone receptor status was known for all patients with 17 (74%) having ER+ disease. Actuarial local control was calculated using the KaplanMeier method. Results: The median follow-up was 18.3 months. The 3-year actuarial local control rate was 93.3%. One recurrence was noted 12 months after IORT in close proximity to tumor bed. This patients was 49 years old at diagnosis and had a 1.2 cm DCIS, grade 3, with solid and cribriform pattern, ER/PR+, and a 0.5 cm closest superior margin. She did not receive endocrine therapy. Conclusion: For selected patients with DCIS, IORT is a feasible treatment option and may be considered as an alternative to conventional whole breast radiation and/or other forms of partial breast radiation. Longer follow-up is needed to prove that this treatment technique offers equal efficacy when compared to the gold standard of whole breast radiation. Author Disclosure: A. Rashtian: None. Y.R. Zhang: None. H.R. Macdonald: None. S.F. Sener: None. M.P. Korah: None. S.Y. Zhou: None. D.R. Holmes: None.
2102 Cardiac Sparing With Breath-hold Technique: A Dosimetric Evaluation of Benefits in Different Patient Populations A. Lin, D. Kim, W. Sharieff, J. Szabo, J. Sussman, I. Dayes, B. Strang, J. Wright, H. Reiter, and T. Whelan; Juravinski Cancer Centre, Hamilton, ON, Canada Purpose/Objective(s): This study aims to evaluate the reduction of cardiac radiation exposure with deep inspiration breath hold (DIBH) technique compared to free breathing (FB) in patients with left-sided breast cancer. The study also aims to evaluate whether the benefits of DIBH vary in patients who had whole breast radiation therapy (RT) after breast conserving therapy (BCT) and those who had chest wall RT postmastectomy (PM). Materials/Methods: FB and DIBH plans were generated for 17 serial PM patients and 15 BCT patients who underwent RT with DIBH using RPM system in 2011. Cardiac shields were used in all BCT plans, provided that clinical treatment volume coverage (i.e. seroma + 1cm) was not compromised, while chest wall coverage took priority in PM plans. The prescribed dose was 50 Gy in 25 fractions for the whole breast or the chest wall. Parameters of interest were cardiac V5, mean LAD dose, maximum LAD dose, and average cardiac dose. The changes in cardiac doses from FB to DIBH were compared in BCT and PM patients using paired t-tests. In order to gauge clinically meaningful outcome, the proportion of patients with V5 < 5% and mean cardiac dose < 2 Gy were compared using McNemar’s test between DIBH and FB subgroups. Results: DIBH decreased V5 (7% vs. 2%; p < 0.001) by a relative reduction of 71.4% in PM group, by 61.1% (3.6% vs. 1.4%; p Z 0.007) in
BCT group. DIBH reduced the mean heart dose by 45.7% (234 cGy vs. 127 cGy; p < 0.001) in PM group, and by 40.3% (139 cGy vs. 84 cGy; p Z 0.001) in BCT group. DIBH reduced mean LAD by 64.2% (1872 cGy vs. 671 cGy; p < 0.001) in PM group, and by 62.5% (1150 cGy vs. 431 cGy; p < 0.001) in BCT group. DIBH also reduced max LAD dose by 30.9% (4020 cGy vs. 2776 cGy; p Z 0.001) in PM group, and by 47.7% (3730 cGy vs. 1952 cGy; p Z 0.001) in BCT group. In BCT group, cardiac V5<5% were achieved in 10/15 (67%) FB patients, and in 15/15 (100%) DIBH patients (p Z 0.002), and average cardiac dose < 2 Gy were achieved in 12/15 (80%) FB patients and in 15/15 (100%) DIBH patients (p < 0.001). This compares with PM group, in which V5<5% were achieved in 6/17 (35%) FB patients and in 16/17 (94%) DIBH patients (p Z 0.05), and average cardiac dose <2 Gy were achieved in 7/17 FB (41%) an 16/17 DIBH patients (94%) (p Z 0.03). Conclusion: The results of this study suggest that there is considerable reduction in cardiac exposure in most patients with DIBH compared to FB. However, dosimetric gains in some BCT cases are small, which may be translatable to only minor measurable clinical benefits. The use of cardiac shields and collimators/ gantry adjustments, more readily applicable for BCT cases, may limit the benefits of DIBH. In an environment where DIBH availability is limited, the result of this study supports the preferential use of DIBH in PM patients over BCT patients. Author Disclosure: A. Lin: None. D. Kim: None. W. Sharieff: None. J. Szabo: None. J. Sussman: None. I. Dayes: None. B. Strang: None. J. Wright: None. H. Reiter: None. T. Whelan: None.
2103 CTV Boost Margin for Adjuvant Breast Radiation Therapy d Results of a Study Comparing US Versus CT Imaging M.G. Sattler and J. Pignol; University of Toronto at Sunnybrook Health Sciences Centre, Toronto, ON, Canada Purpose/Objective(s): A clinical target volume (CTV) boost margin of 10 mm is recommended around the seroma based upon the data from the anatomical distribution of microscopic tumor foci surrounding the primary breast tumor reported in mastectomy and re-lumpectomy specimen studies. For boost delivery and partial breast irradiation, the seroma is defined on Computed Tomography (CT) scan images. On CT, the high-density seroma can include the fluid-filled cavity, but may also include postoperative architectural distortion, breast tissue stranding, fibrosis, adjacent retroareolar tissue, and normal dense breast parenchyma. The purpose of this study is to compare seroma volumes using CT versus US imaging methods and to estimate how much CTV margin expansion corresponds to the volume increase seen on CT. Materials/Methods: As part of a prospective trial of partial breast brachytherapy using a permanent breast seed implant (PBSI) a cohort of patients have been assessed for eligibility using CT simulation and a breast US to identify the seroma. The seroma volume was calculated and the largest orthogonal X (medial-lateral), Y (anterior-posterior) and Z (superior-inferior) diameters were measured on both imaging modalities. A nomogram estimating the volume based on the largest orthogonal X, Y and Z diameters (V Z X*Y*Z*C, with C a normalization constant) was created and were evaluated by comparing the volumes calculated by the Pinnacle planning system and derived from the nomogram. The volumes derived from both imaging modalities were compared with Paired t-tests and the radial expansion between the CT and US seroma volume was calculated assuming that both would be spherical volumes. Results: A total of 183 patients were screened for PBSI between December 2004 and March 2012 and included in this study. A constant of C Z 0.486 fits the volumes best calculated by the treatment planning system and those derived using the orthogonal 3D diameters. The nomogram enables evaluating the seroma volume from the 3D diameters (correlation coefficient r Z 0.975, p < 0.001). Volumes calculated for US were about 4.4 times smaller compared to CT (p < 0.001), with the average volume measured of 3.6 cc and 15 cc for US and CT respectively. The volume excess seen on the CT image would correspond to a median expansion larger than 2.5 mm for 90% of the patients and larger than 5 mm