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Proton Therapy is Dosimetrically Superior to Photon Therapy for Irradiation of the Left Breast and Regional Nodes
Proceedings of the 53rd Annual ASTRO Meeting
S249
normal structures is defined as the volume irradiated by n% of the whole breast prescription dose. The values of lumpectomy PTV_EVAL V120%, and those of heart V40% and V20% for right-sided breast were negligible and not listed in the table. Conclusions: The plan qualities in terms of target coverage and normal tissue sparing for the 7 treatment options allowed in the RTOG 1005 protocol for breast cancer are generally comparable. IMRT for whole breast irradiation and/or boost provides slightly better dose uniformity and/or normal tissue sparing than other options. Table Plan Options Lumpectomy PTV_EVAL Breast PTV_EVAL Contralateral Breast Ipsilateral Lung
D5/D95 V95% V95%\ V108%\ V120% Max/ WBI Dose (%) Supine
Prone
Contralateral Lung Heart
V10% Left-sided Breast
Right-sided Breast
V40%\ V20%\ V10% V40%\ V20%\ V10% V40%\ V20%\ Mean/ WBI Dose Mean/ WBI Dose (%)
1
2
3
4
5
6
7
1.09 97.80 95.07\ 42.34\ 20.00 4.40
1.09 96.41 96.45\ 46.16\ 18.62 4.34
1.08 95.38 95.89\ 52.34\ 12.59 4.46
1.09 98.14 95.30\ 41.07\ 17.82 4.03
1.08 96.77 96.11\ 42.97\ 17.39 3.76
1.08 96.02 96.58\ 50.80\ 11.02 3.76
1.10 91.46 91.69\ 51.03\ 8.64 3.51
15.53\ 22.74\ 33.84 3.32\ 5.25\ 7.58 0.00 3.95\ 6.42\ 7.02
16.20\ 26.60\ 51.77 3.33\ 5.26\ 7.62 1.94 3.94\ 6.39\ 7.03
14.12\ 19.56\ 26.28 3.12\ 5.01\ 7.29 0.00 3.76\ 6.02\ 6.88
15.58\ 23.25\ 35.86 3.56\ 4.88\ 6.83 0.00 4.08\ 7.20\ 6.31
16.00\ 26.97\ 52.09 3.56\ 4.87\ 6.85 1.98 3.99\ 7.12\ 6.24
13.95\ 19.66\ 26.53 3.57\ 4.89\ 6.91 0.00 4.06\ 7.22\ 6.29
15.59\ 20.91\ 27.07 3.59\ 5.15\ 7.43 0.00 4.05\ 8.36\ 6.95
1.25
3.04
0.89
1.37
3.04
0.96
0.88
Author Disclosure: G. Chen: None. J. White: None. F.A. Vicini: None. G.M. Freedman: None. A. Li: None.
2076
Proton Therapy is Dosimetrically Superior to Photon Therapy for Irradiation of the Left Breast and Regional Nodes
S. Grover, L. Lin, K. Teo, J. W. Zou, D. Dolney, R. Prosnitz University of Pennsylvania, Philadelphia, PA Purpose/Objective(s): Although improvements in photon radiation therapy techniques in recent years have reduced incidental irradiation of the heart and lungs, concerns remain about the risks of both short and long-term toxicity. Furthermore, complex field matching techniques required to treat the internal mammary nodes may compromise coverage of the target volumes in some cases. Intensity modulated proton therapy (IMPT) has the potential to reduce dose to organs at risk, specifically the whole heart and left lung, and has been demonstrated to be superior compared to three-dimensional conformal radiation therapy (3D-CRT) when the PTV includes the whole breast/chest wall, supraclavicular (SCV) , axillary (AX III), and internal mammary nodes (IMN). The goal of our study was to further characterize the dose reduction to OARs, specifically cardiac substructures approximating the chest wall to better quantify the dosimetric benefits of IMPT. Materials/Methods: Using the Eclipse treatment planning system, comparative treatment planning was performed using the planning computed tomography scans for eight patients with left sided breast cancer. All patients underwent 4D-CT and cardiac MRI. IGTV, CTV and PTV were created, and PTV was finally defined as: whole breast/chest wall + SCV+ AX III and IMN. For each patient, 3DCRT and IMPT plans were optimized for PTV coverage. This abstract is presenting our findings from data on free breathing 3D-CRT and IMPT plans. Results: V95% of the breast PTV was 95% for IMPT vs 90% for 3D-CRT. V107% for the breast only patients was 1% vs 6 % in IMPT vs 3D-CRT respectively. Left lung dose for IMPT plans was about 50% less than the 3D-CRT plans: mean left lung dose 8Gy vs 15 Gy and V20 18% vs 31% for IMPT vs 3D-CRT respectively. Heart dose for IMPT plans was 50% less than the 3D-CRT plans: V5 8% vs 16% and mean heart dose 1.8Gy vs 3.9 Gy. Left anterior descending artery (LAD) dose in IMPT plans was 20% less than the 3D-CRT plans for low dose: V5 62% vs 80%, V10 47% vs 60% and 40% less for high dose: V20 31% and 50% for IMPTand 3DCRT respectively. Left ventricle (LV) dose for IMPTwas lower that the 3D-CRT plan: V5 8% vs 23%, V10 5% vs 8%, V20 was 2% vs 4%. Mean maximum skin dose for breast conservation patients was 50Gy with IMPT and 47Gy with 3D-CRT. Conclusions: IMPT is superior to 3D-CRT in regards to coverage, homogeneity, and dose to OARs in women undergoing RT to the left breast and regional nodes. Dose to the lung, heart and sub-structures of heart (LVand LAD) is reduced with IMPT. Higher skin doses may be seen with IMPT with breast conservation. Prospective clinical studies are needed to determine whether IMPT can potentially reduce clinically significant cardiac morbidity. Author Disclosure: S. Grover: None. L. Lin: None. K. Teo: None. J.W. Zou: None. D. Dolney: None. R. Prosnitz: None.
2077
The Impact of Lymph Node Status on Clinical Outcomes following Accelerated Partial Breast Irradiation
F. A. Vicini, C. Shah, J. B. Wilkinson, M. Wallace, C. Mitchell William Beaumont Hospital, Royal Oak, MI Purpose/Objective(s): To compare clinical outcomes following accelerated partial breast irradiation (APBI) between node-negative and node-positive early stage breast cancer patients.
S249
normal structures is defined as the volume irradiated by n% of the whole breast prescription dose. The values of lumpectomy PTV_EVAL V120%, and those of heart V40% and V20% for right-sided breast were negligible and not listed in the table. Conclusions: The plan qualities in terms of target coverage and normal tissue sparing for the 7 treatment options allowed in the RTOG 1005 protocol for breast cancer are generally comparable. IMRT for whole breast irradiation and/or boost provides slightly better dose uniformity and/or normal tissue sparing than other options. Table Plan Options Lumpectomy PTV_EVAL Breast PTV_EVAL Contralateral Breast Ipsilateral Lung
D5/D95 V95% V95%\ V108%\ V120% Max/ WBI Dose (%) Supine
Prone
Contralateral Lung Heart
V10% Left-sided Breast
Right-sided Breast
V40%\ V20%\ V10% V40%\ V20%\ V10% V40%\ V20%\ Mean/ WBI Dose Mean/ WBI Dose (%)
1
2
3
4
5
6
7
1.09 97.80 95.07\ 42.34\ 20.00 4.40
1.09 96.41 96.45\ 46.16\ 18.62 4.34
1.08 95.38 95.89\ 52.34\ 12.59 4.46
1.09 98.14 95.30\ 41.07\ 17.82 4.03
1.08 96.77 96.11\ 42.97\ 17.39 3.76
1.08 96.02 96.58\ 50.80\ 11.02 3.76
1.10 91.46 91.69\ 51.03\ 8.64 3.51
15.53\ 22.74\ 33.84 3.32\ 5.25\ 7.58 0.00 3.95\ 6.42\ 7.02
16.20\ 26.60\ 51.77 3.33\ 5.26\ 7.62 1.94 3.94\ 6.39\ 7.03
14.12\ 19.56\ 26.28 3.12\ 5.01\ 7.29 0.00 3.76\ 6.02\ 6.88
15.58\ 23.25\ 35.86 3.56\ 4.88\ 6.83 0.00 4.08\ 7.20\ 6.31
16.00\ 26.97\ 52.09 3.56\ 4.87\ 6.85 1.98 3.99\ 7.12\ 6.24
13.95\ 19.66\ 26.53 3.57\ 4.89\ 6.91 0.00 4.06\ 7.22\ 6.29
15.59\ 20.91\ 27.07 3.59\ 5.15\ 7.43 0.00 4.05\ 8.36\ 6.95
1.25
3.04
0.89
1.37
3.04
0.96
0.88
Author Disclosure: G. Chen: None. J. White: None. F.A. Vicini: None. G.M. Freedman: None. A. Li: None.
2076
Proton Therapy is Dosimetrically Superior to Photon Therapy for Irradiation of the Left Breast and Regional Nodes
S. Grover, L. Lin, K. Teo, J. W. Zou, D. Dolney, R. Prosnitz University of Pennsylvania, Philadelphia, PA Purpose/Objective(s): Although improvements in photon radiation therapy techniques in recent years have reduced incidental irradiation of the heart and lungs, concerns remain about the risks of both short and long-term toxicity. Furthermore, complex field matching techniques required to treat the internal mammary nodes may compromise coverage of the target volumes in some cases. Intensity modulated proton therapy (IMPT) has the potential to reduce dose to organs at risk, specifically the whole heart and left lung, and has been demonstrated to be superior compared to three-dimensional conformal radiation therapy (3D-CRT) when the PTV includes the whole breast/chest wall, supraclavicular (SCV) , axillary (AX III), and internal mammary nodes (IMN). The goal of our study was to further characterize the dose reduction to OARs, specifically cardiac substructures approximating the chest wall to better quantify the dosimetric benefits of IMPT. Materials/Methods: Using the Eclipse treatment planning system, comparative treatment planning was performed using the planning computed tomography scans for eight patients with left sided breast cancer. All patients underwent 4D-CT and cardiac MRI. IGTV, CTV and PTV were created, and PTV was finally defined as: whole breast/chest wall + SCV+ AX III and IMN. For each patient, 3DCRT and IMPT plans were optimized for PTV coverage. This abstract is presenting our findings from data on free breathing 3D-CRT and IMPT plans. Results: V95% of the breast PTV was 95% for IMPT vs 90% for 3D-CRT. V107% for the breast only patients was 1% vs 6 % in IMPT vs 3D-CRT respectively. Left lung dose for IMPT plans was about 50% less than the 3D-CRT plans: mean left lung dose 8Gy vs 15 Gy and V20 18% vs 31% for IMPT vs 3D-CRT respectively. Heart dose for IMPT plans was 50% less than the 3D-CRT plans: V5 8% vs 16% and mean heart dose 1.8Gy vs 3.9 Gy. Left anterior descending artery (LAD) dose in IMPT plans was 20% less than the 3D-CRT plans for low dose: V5 62% vs 80%, V10 47% vs 60% and 40% less for high dose: V20 31% and 50% for IMPTand 3DCRT respectively. Left ventricle (LV) dose for IMPTwas lower that the 3D-CRT plan: V5 8% vs 23%, V10 5% vs 8%, V20 was 2% vs 4%. Mean maximum skin dose for breast conservation patients was 50Gy with IMPT and 47Gy with 3D-CRT. Conclusions: IMPT is superior to 3D-CRT in regards to coverage, homogeneity, and dose to OARs in women undergoing RT to the left breast and regional nodes. Dose to the lung, heart and sub-structures of heart (LVand LAD) is reduced with IMPT. Higher skin doses may be seen with IMPT with breast conservation. Prospective clinical studies are needed to determine whether IMPT can potentially reduce clinically significant cardiac morbidity. Author Disclosure: S. Grover: None. L. Lin: None. K. Teo: None. J.W. Zou: None. D. Dolney: None. R. Prosnitz: None.
2077
The Impact of Lymph Node Status on Clinical Outcomes following Accelerated Partial Breast Irradiation
F. A. Vicini, C. Shah, J. B. Wilkinson, M. Wallace, C. Mitchell William Beaumont Hospital, Royal Oak, MI Purpose/Objective(s): To compare clinical outcomes following accelerated partial breast irradiation (APBI) between node-negative and node-positive early stage breast cancer patients.