- Email: [email protected]
Prospective Use of a Conformity Index May Reduce Planning Variability for Multi-institutional Clinical Protocols
Proceedings of the 52nd Annual ASTRO Meeting predicted the likelihood of poor outcomes prior to the intervention, and 25 (86%) after (p = 0.01). Six patients (22%) correctly identified breast size as the most noticeable change post-radiation on the first survey and 15 (52%) after (p = 0.03). The number of patients’ feeling well-informed (quite a bit, very much) increased from 72% prior to viewing the photographs to 93% afterwards (p = NS). Decision satisfaction was high pre (97%; 28/29) and post (93%; 28/30) intervention (p = NS). Conclusions: This photograph-based educational tool appears to be a simple and effective way to improve patients’ understanding of potential cosmetic outcomes after BCT, beyond that accomplished through standard radiation oncology consultation. Confirmation and refinement in a larger study is indicated. Author Disclosure: M.M. Shah, None; J. Peppercorn, None; C.N. Lee, None; G. Broadwater, None; J.K. Horton, None.
2063
How to Predict Patients Unsuitable for Accelerated Partial Breast Irradiation (APBI) using 3D Conformal Techniques
N. Shikama, N. Nakamura, N. Kunishima, K. Sekiguchi St Lukes International Hospital, Tokyo, Japan Purpose/Objective(s): The efficacy and safety of APBI using small radiation fields and a large fraction size have been evaluated by prospective clinical trials and retrospective studies. Some recent studies reported that severe late toxicities such as soft tissue fibrosis and fat necrosis, which were clearly associated with marked cosmetic compromise, were observed in patients with a large irradiated volume and a high dose. This study was performed to clarify unsuitable patients for APBI using three-dimensional conformal radiotherapy (3D-CRT). Materials/Methods: Fifty consecutive patients with stage I or II unilateral breast cancer who received breast-conserving therapy were evaluated. The median age was 49 years. The right-to-left ratio of the ipsilateral breast (IB) was 25:25, and the medial-tolateral ratio of the tumor location was 19:31. All patients underwent partial breast resection, and five or six surgical clips were placed in the resection margin. All patients were subsequently replanned using 3D-CRT APBI techniques according to RTOG protocol 0413. The clinical target volume (CTV) was defined as the surgical clips plus a 1.5-cm margin excluding the pectoralis muscles, chest wall, and 5 mm beneath the skin. Planning target volume (PTV) was defined as the CTV plus a 1.0-cm margin. The beam arrangements included non-coplanar 4- or 5-field beams using 6 MV photons. The IB volume excluding the PTV (IB-PTV), which represented the uninvolved ipsilateral breast, and the IB volume receiving 50% (V50) of the prescribed dose were calculated. Results: The median IB-PTV/IB ratio was 74.9% (range: 54.0-86.9). Dose-volume histogram (DVH) constraints for organ at risk according to RTOG 0413 were satisfied in 39 patients (78%). Univariate logistic regression analysis revealed that a long cranio-caudal clip distance (CCD) and medial tumor were correlated with unsatisfactory DVH constraints (p\0.0001 and p = 0.007), but the anteroposterior clip distance (APD), site of IB (right/left), and IB volume were not (p = 0.54, p = 0.73, and p = 0.10, respectively). Multivariate analysis revealed that only a long CCD was correlated with unsatisfactory DVH constraints (p = 0.02). DVH constraints were satisfied in 20% of the patients with a long CCD (.5.5 cm) and 92% of those with a short CCD (p\0.0001). The median V50 was 49% (range: 31.4-68.6), and multivariate analysis revealed that a long CCD and long APD were correlated with a large V50 (p\0.001 and p = 0.03, respectively), but the location of the tumor (medial/lateral) and IB volume were not (p = 0.61 and p = 0.17, respectively). The median V50 of the patients with a long APD (.4 cm) and that of patients with a short APD were 50.8 and 46.8%, respectively (p = 0.04). Conclusions: Patients with a long CCD (.5.5 cm) and/or long APD (.4 cm) are unsuitable for 3D-CRT APBI. Author Disclosure: N. Shikama, None; N. Nakamura, None; N. Kunishima, None; K. Sekiguchi, None.
2064
Prospective Use of a Conformity Index May Reduce Planning Variability for Multi-institutional Clinical Protocols
M. J. Tallhamer1, S. R. Armour1, K. Caldwell1, K. Howell2, C. Leonard2, D. Carter1 1
Rocky Mountain Cancer Centers, Aurora, CO, 2Rocky Mountain Cancer Centers, Littleton, CO
Purpose/Objective(s): The random and systematic causes of variation in multi-institutional clinical protocols is important when making predictions related to outcomes, toxicities and efficacy. Our purpose was to evaluate the utility of a conformity index (CI) to quantify and prospectively improve the variation among treatment plans for patients undergoing treatment on a multi-institutional clinical protocol. Materials/Methods: From 2/04 to 6/09, 254 patients with stage I breast cancer at 4 facilities were treated on a prospective phase II accelerated partial breast IMRT protocol. Patients were treated twice daily over 5 consecutive days to a total dose of 38.5 Gy. All treatment plans were subject to compliance with protocol dose-volume constraints. Data from 73 of these treatment plans were available on a centralized computer database for additional retrospective analysis, representing 2 institutions and the work of 3 physicians and 5 dosimetrists. An internally developed software program computed the CI graphs to assess the treatment plan quality at 3 points: the CI at 95% of the prescription dose, the CI at the prescription dose, and the minimum CI. The conformity parameters from these initial treatment plans were then incorporated prospectively with additional planning objectives into a phase III randomized accelerated partial breast IMRT vs. 3D protocol. Treatment plans for the first 43 patients receiving IMRT accrued to the new protocol from the same 2 institutions were then evaluated to investigate possible changes in the treatment plan quality. Results: The minimum CI was determined to be a good representative assessment of conformity and was selected for all subsequent comparisons while the CI at the prescription dose and at 95% of the prescription dose also show similar statistics and are reported. Protocol dose-volume constraints were similarly met in all plans. The addition of CI as an objective did not significantly impact coverage of the PTV or increase dose inhomogeneity (p = 0.015), but did reduce dose to normal tissue through improved mean conformity (p \ 0.001) and also reduced overall CI variability (p = 0.001). The original mean CI was 0.262 (SD = 0.098, range, 0.74-0.526), improving to 0.194 (SD = 0.062, range, 0.088-0.311) when used as a prospective objective. For each of the 3 physicians, both the average CI and the variability of the CI improved. Conclusions: The addition of a conformity index to commonly imposed dose-volume objectives, as a prospective evaluation criterion in multi-institutional clinical protocols, can significantly improving dose conformity while maintaining target coverage and reducing variation in plan quality.
S233
I. J. Radiation Oncology d Biology d Physics
S234
Volume 78, Number 3, Supplement, 2010
Author Disclosure: M.J. Tallhamer, None; S.R. Armour, None; K. Caldwell, None; K. Howell, None; C. Leonard, None; D. Carter, None.
2065
Tissue Compliance Meter is a More Reproducible Method of Measuring Radiation-induced Fibrosis Than LENT-SOMA in Patients Treated with Intracavitary Brachytherapy Accelerated Partial Breast Irradiation: Results of a Prospective Trial
G. A. Wernicke, B. Parashar, M. K. Hayes, S. Trichter, L. Riley, E. J. Nowak, R. M. Simmons, A. J. Swistel, D. Nori, K. Chao Weill Cornell University, New York, NY Purpose/Objective(s): Identification of radiation-induced fibrosis (RIF) remains a challenge with LENT-SOMA. Tissue compliance meter (TCM), a novel external applicator, may render a more reproducible tool for measuring RIF. In this study, we quantify RIF after intracavitary brachytherapy (IB) accelerated partial breast irradiation (APBI) with TCM and compare it with LENT-SOMA. Materials/Methods: Thirty-eight breasts of women with AJCC Stage 0-I breast cancer treated with lumpectomy and IBAPBI were evaluated by 2 raters in a prospective manner pre-IBAPBI and every 6 months post-IBAPBI for development of RIF, using TCM and LENT-SOMA. A dose of 34 Gy (3.4 Gy/fx BID) was prescribed to 1.0cm from the balloon (33 MammoSite and 6 Contura). TCM classification scale grades RIF as 0 = none, 1 = mild, 2 = moderate, and 3 = severe, corresponding to a change in TCM (DTCM) between the IBAPBI and non-irradiated breasts of #2.9, 3.0-5.9, 6.0-8.9, $9.0 mm, respectively. LENT-SOMA scale employs clinical palpation to grade RIF as 0 = none, 1 = mild, 2 = moderate, and 3 = severe. Correlation coefficients - Intraclass (ICC), Pearson (r), and Cohen’s kappa (k) - were employed to assess reliability of TCM and LENT-SOMA. Multivariate and univariate linear models explored the relationship between RIF and anatomical parameters (bra cup size, body mass index), exposure to estrogen (menarche, menopause, oral contraceptives, hormonal replacement therapy, hormonal therapy), and dosimetric factors (balloon diameter, skin-to-balloon distance [SBD], V150, and V200). Results: Median time to follow-up from completion of IBAPBI is 2.8 years (range, 0.1-3.6 years). Median age is 68 years (range, 47-82 years). Median breast cup size is 39D (range, 34B-44DDD). Median balloon size is 41.2 cc (range, 37.6-50.0 cc), and median SBD is 1.4 cm (range, 0.2-5.5 cm). At pre-IBAPBI, TCM measurements demonstrate high inter-observer agreement between 2 raters in all 4 quadrants of both breasts ICC $0.997 (95% CI 0.994-0.998). At 30 months post-IBAPBI, TCM measurements for 2 raters render ICC = 0.992 (95% CI 0.987-0.995) and r = 0.983, p \ 0.0001, whereas LENT-SOMA demonstrates k = 0.45 (95% CI 0.18-0.80). After 30 months, RIF is graded by TCM scale as 0, 1, 2, and 3 in 7/38 (19%), 17/38 (44%), 11/38 (29%), and 3/38 (8%) of patients, respectively. DTCM $6 mm (moderate-severe RIF) is statistically different from DTCM #3 mm (none-mild RIF) (p \ 0.05). SBD and V150 are the only factors closest to 0.05 significance of contributing to RIF. Conclusions: This prospective study indicates that TCM is a more reproducible methodology than LENT-SOMA in measuring RIF in patients treated with IBAPBI. This tool renders a promising future application in assessing RIF. Author Disclosure: G.A. Wernicke, None; B. Parashar, None; M.K. Hayes, None; S. Trichter, None; L. Riley, None; E.J. Nowak, None; R.M. Simmons, None; A.J. Swistel, None; D. Nori, None; K. Chao, None.
2066
Outcomes of Breast Cancer Patients with Triple Negative Receptor Status Treated with Accelerated Partial Breast Irradiation
J. B. Wilkinson, M. Wallace, P. Y. Chen, C. Mitchell, S. F. Shaitelman, K. Marvin, I. S. Grills, F. A. Vicini William Beaumont Hospital, Royal Oak, MI Purpose/Objective(s): Triple negative receptor status (TNRS) is associated with increased distant metastasis, decreased diseasefree survival, and decreased overall survival for women who receive whole breast irradiation as part of breast conserving therapy. This report aims to define the clinical outcomes of patients with TNRS treated with accelerated partial breast irradiation (APBI). Materials/Methods: We studied 455 patients who received APBI at our institution between February 1993 and July 2009 who had a minimum follow-up of six months. Methods of delivering APBI included interstitial brachytherapy (n = 202), balloon-based intracavitary brachytherapy (n = 146), and 3D-conformal external beam partial breast irradiation (n = 105). HER-2/neu testing for our breast cancer patients was implemented in October 1999. Using an IRB-approved registry, a query was performed to identify patients who received receptor status testing. Patients were classified as TNRS if they tested negative for all three (ER, PR, and HER-2/neu) cell membrane markers. Of 202 patients with all marker results available, 20 were classified as triple negative (TNRS cohort) and 182 were coded as having both HER-2/neu testing with at least one receptor positive (RP cohort). Pearson’s Chisquared and actuarial analyses were used to compare the two cohorts with regards to patient demographics, ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), overall survival (OS), cause-specific survival (CSS), and distant metastasis (DM). Results: Mean follow-up was 7.1 years for all patients (4.1 years for TNRS group and 5.1 years for RP cohort, p = 0.11). Overall, TNRS patients presented with a higher histologic grade with 59% classified as grade 3 vs. 13% of the non-TNRS patients (p \ 0.001). Mean tumor size (11 mm vs. 10 mm), N1 disease (5% vs. 7%), and margin status (6% vs. 10% with a margin \ 2 mm) were similar between the two groups (TNRS and RP respectively, p . 0.36). More TNRS than RP patients received chemotherapy (74% vs. 20%, p\0.001). Based on a 5-year actuarial analysis, the TNRS cohort experienced no IBRT, RNF, or DM with an OS of 100%. This is compared with a 1.4% IBTR, 1.5% RNF, and 2.8% DM rate in the RP cohort, which was not statistically different (p . 0.52). OS for the RP cohort was 93% with a CSS of 99% and DFS of 93% at five years (p . 0.28). Conclusions: This is the first known report of the effect of TNRS on clinical outcomes for patients treated with APBI. In our single institution review, TNRS conferred a similar clinical outcome when compared to patients with RP disease treated with APBI. Further investigation with larger patient populations and longer follow-up is warranted to confirm that APBI is a safe and effective treatment choice for patients with TNRS breast cancer. Author Disclosure: J.B. Wilkinson, None; M. Wallace, None; P.Y. Chen, None; C. Mitchell, None; S.F. Shaitelman, None; K. Marvin, None; I.S. Grills, None; F.A. Vicini, None.
2063
How to Predict Patients Unsuitable for Accelerated Partial Breast Irradiation (APBI) using 3D Conformal Techniques
N. Shikama, N. Nakamura, N. Kunishima, K. Sekiguchi St Lukes International Hospital, Tokyo, Japan Purpose/Objective(s): The efficacy and safety of APBI using small radiation fields and a large fraction size have been evaluated by prospective clinical trials and retrospective studies. Some recent studies reported that severe late toxicities such as soft tissue fibrosis and fat necrosis, which were clearly associated with marked cosmetic compromise, were observed in patients with a large irradiated volume and a high dose. This study was performed to clarify unsuitable patients for APBI using three-dimensional conformal radiotherapy (3D-CRT). Materials/Methods: Fifty consecutive patients with stage I or II unilateral breast cancer who received breast-conserving therapy were evaluated. The median age was 49 years. The right-to-left ratio of the ipsilateral breast (IB) was 25:25, and the medial-tolateral ratio of the tumor location was 19:31. All patients underwent partial breast resection, and five or six surgical clips were placed in the resection margin. All patients were subsequently replanned using 3D-CRT APBI techniques according to RTOG protocol 0413. The clinical target volume (CTV) was defined as the surgical clips plus a 1.5-cm margin excluding the pectoralis muscles, chest wall, and 5 mm beneath the skin. Planning target volume (PTV) was defined as the CTV plus a 1.0-cm margin. The beam arrangements included non-coplanar 4- or 5-field beams using 6 MV photons. The IB volume excluding the PTV (IB-PTV), which represented the uninvolved ipsilateral breast, and the IB volume receiving 50% (V50) of the prescribed dose were calculated. Results: The median IB-PTV/IB ratio was 74.9% (range: 54.0-86.9). Dose-volume histogram (DVH) constraints for organ at risk according to RTOG 0413 were satisfied in 39 patients (78%). Univariate logistic regression analysis revealed that a long cranio-caudal clip distance (CCD) and medial tumor were correlated with unsatisfactory DVH constraints (p\0.0001 and p = 0.007), but the anteroposterior clip distance (APD), site of IB (right/left), and IB volume were not (p = 0.54, p = 0.73, and p = 0.10, respectively). Multivariate analysis revealed that only a long CCD was correlated with unsatisfactory DVH constraints (p = 0.02). DVH constraints were satisfied in 20% of the patients with a long CCD (.5.5 cm) and 92% of those with a short CCD (p\0.0001). The median V50 was 49% (range: 31.4-68.6), and multivariate analysis revealed that a long CCD and long APD were correlated with a large V50 (p\0.001 and p = 0.03, respectively), but the location of the tumor (medial/lateral) and IB volume were not (p = 0.61 and p = 0.17, respectively). The median V50 of the patients with a long APD (.4 cm) and that of patients with a short APD were 50.8 and 46.8%, respectively (p = 0.04). Conclusions: Patients with a long CCD (.5.5 cm) and/or long APD (.4 cm) are unsuitable for 3D-CRT APBI. Author Disclosure: N. Shikama, None; N. Nakamura, None; N. Kunishima, None; K. Sekiguchi, None.
2064
Prospective Use of a Conformity Index May Reduce Planning Variability for Multi-institutional Clinical Protocols
M. J. Tallhamer1, S. R. Armour1, K. Caldwell1, K. Howell2, C. Leonard2, D. Carter1 1
Rocky Mountain Cancer Centers, Aurora, CO, 2Rocky Mountain Cancer Centers, Littleton, CO
Purpose/Objective(s): The random and systematic causes of variation in multi-institutional clinical protocols is important when making predictions related to outcomes, toxicities and efficacy. Our purpose was to evaluate the utility of a conformity index (CI) to quantify and prospectively improve the variation among treatment plans for patients undergoing treatment on a multi-institutional clinical protocol. Materials/Methods: From 2/04 to 6/09, 254 patients with stage I breast cancer at 4 facilities were treated on a prospective phase II accelerated partial breast IMRT protocol. Patients were treated twice daily over 5 consecutive days to a total dose of 38.5 Gy. All treatment plans were subject to compliance with protocol dose-volume constraints. Data from 73 of these treatment plans were available on a centralized computer database for additional retrospective analysis, representing 2 institutions and the work of 3 physicians and 5 dosimetrists. An internally developed software program computed the CI graphs to assess the treatment plan quality at 3 points: the CI at 95% of the prescription dose, the CI at the prescription dose, and the minimum CI. The conformity parameters from these initial treatment plans were then incorporated prospectively with additional planning objectives into a phase III randomized accelerated partial breast IMRT vs. 3D protocol. Treatment plans for the first 43 patients receiving IMRT accrued to the new protocol from the same 2 institutions were then evaluated to investigate possible changes in the treatment plan quality. Results: The minimum CI was determined to be a good representative assessment of conformity and was selected for all subsequent comparisons while the CI at the prescription dose and at 95% of the prescription dose also show similar statistics and are reported. Protocol dose-volume constraints were similarly met in all plans. The addition of CI as an objective did not significantly impact coverage of the PTV or increase dose inhomogeneity (p = 0.015), but did reduce dose to normal tissue through improved mean conformity (p \ 0.001) and also reduced overall CI variability (p = 0.001). The original mean CI was 0.262 (SD = 0.098, range, 0.74-0.526), improving to 0.194 (SD = 0.062, range, 0.088-0.311) when used as a prospective objective. For each of the 3 physicians, both the average CI and the variability of the CI improved. Conclusions: The addition of a conformity index to commonly imposed dose-volume objectives, as a prospective evaluation criterion in multi-institutional clinical protocols, can significantly improving dose conformity while maintaining target coverage and reducing variation in plan quality.
S233
I. J. Radiation Oncology d Biology d Physics
S234
Volume 78, Number 3, Supplement, 2010
Author Disclosure: M.J. Tallhamer, None; S.R. Armour, None; K. Caldwell, None; K. Howell, None; C. Leonard, None; D. Carter, None.
2065
Tissue Compliance Meter is a More Reproducible Method of Measuring Radiation-induced Fibrosis Than LENT-SOMA in Patients Treated with Intracavitary Brachytherapy Accelerated Partial Breast Irradiation: Results of a Prospective Trial
G. A. Wernicke, B. Parashar, M. K. Hayes, S. Trichter, L. Riley, E. J. Nowak, R. M. Simmons, A. J. Swistel, D. Nori, K. Chao Weill Cornell University, New York, NY Purpose/Objective(s): Identification of radiation-induced fibrosis (RIF) remains a challenge with LENT-SOMA. Tissue compliance meter (TCM), a novel external applicator, may render a more reproducible tool for measuring RIF. In this study, we quantify RIF after intracavitary brachytherapy (IB) accelerated partial breast irradiation (APBI) with TCM and compare it with LENT-SOMA. Materials/Methods: Thirty-eight breasts of women with AJCC Stage 0-I breast cancer treated with lumpectomy and IBAPBI were evaluated by 2 raters in a prospective manner pre-IBAPBI and every 6 months post-IBAPBI for development of RIF, using TCM and LENT-SOMA. A dose of 34 Gy (3.4 Gy/fx BID) was prescribed to 1.0cm from the balloon (33 MammoSite and 6 Contura). TCM classification scale grades RIF as 0 = none, 1 = mild, 2 = moderate, and 3 = severe, corresponding to a change in TCM (DTCM) between the IBAPBI and non-irradiated breasts of #2.9, 3.0-5.9, 6.0-8.9, $9.0 mm, respectively. LENT-SOMA scale employs clinical palpation to grade RIF as 0 = none, 1 = mild, 2 = moderate, and 3 = severe. Correlation coefficients - Intraclass (ICC), Pearson (r), and Cohen’s kappa (k) - were employed to assess reliability of TCM and LENT-SOMA. Multivariate and univariate linear models explored the relationship between RIF and anatomical parameters (bra cup size, body mass index), exposure to estrogen (menarche, menopause, oral contraceptives, hormonal replacement therapy, hormonal therapy), and dosimetric factors (balloon diameter, skin-to-balloon distance [SBD], V150, and V200). Results: Median time to follow-up from completion of IBAPBI is 2.8 years (range, 0.1-3.6 years). Median age is 68 years (range, 47-82 years). Median breast cup size is 39D (range, 34B-44DDD). Median balloon size is 41.2 cc (range, 37.6-50.0 cc), and median SBD is 1.4 cm (range, 0.2-5.5 cm). At pre-IBAPBI, TCM measurements demonstrate high inter-observer agreement between 2 raters in all 4 quadrants of both breasts ICC $0.997 (95% CI 0.994-0.998). At 30 months post-IBAPBI, TCM measurements for 2 raters render ICC = 0.992 (95% CI 0.987-0.995) and r = 0.983, p \ 0.0001, whereas LENT-SOMA demonstrates k = 0.45 (95% CI 0.18-0.80). After 30 months, RIF is graded by TCM scale as 0, 1, 2, and 3 in 7/38 (19%), 17/38 (44%), 11/38 (29%), and 3/38 (8%) of patients, respectively. DTCM $6 mm (moderate-severe RIF) is statistically different from DTCM #3 mm (none-mild RIF) (p \ 0.05). SBD and V150 are the only factors closest to 0.05 significance of contributing to RIF. Conclusions: This prospective study indicates that TCM is a more reproducible methodology than LENT-SOMA in measuring RIF in patients treated with IBAPBI. This tool renders a promising future application in assessing RIF. Author Disclosure: G.A. Wernicke, None; B. Parashar, None; M.K. Hayes, None; S. Trichter, None; L. Riley, None; E.J. Nowak, None; R.M. Simmons, None; A.J. Swistel, None; D. Nori, None; K. Chao, None.
2066
Outcomes of Breast Cancer Patients with Triple Negative Receptor Status Treated with Accelerated Partial Breast Irradiation
J. B. Wilkinson, M. Wallace, P. Y. Chen, C. Mitchell, S. F. Shaitelman, K. Marvin, I. S. Grills, F. A. Vicini William Beaumont Hospital, Royal Oak, MI Purpose/Objective(s): Triple negative receptor status (TNRS) is associated with increased distant metastasis, decreased diseasefree survival, and decreased overall survival for women who receive whole breast irradiation as part of breast conserving therapy. This report aims to define the clinical outcomes of patients with TNRS treated with accelerated partial breast irradiation (APBI). Materials/Methods: We studied 455 patients who received APBI at our institution between February 1993 and July 2009 who had a minimum follow-up of six months. Methods of delivering APBI included interstitial brachytherapy (n = 202), balloon-based intracavitary brachytherapy (n = 146), and 3D-conformal external beam partial breast irradiation (n = 105). HER-2/neu testing for our breast cancer patients was implemented in October 1999. Using an IRB-approved registry, a query was performed to identify patients who received receptor status testing. Patients were classified as TNRS if they tested negative for all three (ER, PR, and HER-2/neu) cell membrane markers. Of 202 patients with all marker results available, 20 were classified as triple negative (TNRS cohort) and 182 were coded as having both HER-2/neu testing with at least one receptor positive (RP cohort). Pearson’s Chisquared and actuarial analyses were used to compare the two cohorts with regards to patient demographics, ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), overall survival (OS), cause-specific survival (CSS), and distant metastasis (DM). Results: Mean follow-up was 7.1 years for all patients (4.1 years for TNRS group and 5.1 years for RP cohort, p = 0.11). Overall, TNRS patients presented with a higher histologic grade with 59% classified as grade 3 vs. 13% of the non-TNRS patients (p \ 0.001). Mean tumor size (11 mm vs. 10 mm), N1 disease (5% vs. 7%), and margin status (6% vs. 10% with a margin \ 2 mm) were similar between the two groups (TNRS and RP respectively, p . 0.36). More TNRS than RP patients received chemotherapy (74% vs. 20%, p\0.001). Based on a 5-year actuarial analysis, the TNRS cohort experienced no IBRT, RNF, or DM with an OS of 100%. This is compared with a 1.4% IBTR, 1.5% RNF, and 2.8% DM rate in the RP cohort, which was not statistically different (p . 0.52). OS for the RP cohort was 93% with a CSS of 99% and DFS of 93% at five years (p . 0.28). Conclusions: This is the first known report of the effect of TNRS on clinical outcomes for patients treated with APBI. In our single institution review, TNRS conferred a similar clinical outcome when compared to patients with RP disease treated with APBI. Further investigation with larger patient populations and longer follow-up is warranted to confirm that APBI is a safe and effective treatment choice for patients with TNRS breast cancer. Author Disclosure: J.B. Wilkinson, None; M. Wallace, None; P.Y. Chen, None; C. Mitchell, None; S.F. Shaitelman, None; K. Marvin, None; I.S. Grills, None; F.A. Vicini, None.