- Email: [email protected]
Dosimetric Comparison Between 2D and 3D Treatment Planning in Breast Cancer When Using the RTOG Breast Contouring Atlas
E50
International Journal of Radiation Oncology Biology Physics
2116
to minimize dose delivered to the heart. However, treatment planning assumes a static position of the heart on simulation CT. We hypothesized that variation in heart position during RT delivery due to normal respiratory and cardiac function impacts the dose delivered to the heart and that the delivered dose is significantly different from the planned dose. We conducted a study utilizing cine MRI to quantify cardiac motion and to determine its dosimetric impact. Materials/Methods: Cine MR images (1.5T) were acquired in both freebreathing (FB) and deep inspiration breath hold (DIBH) for 9 healthy volunteers and 8 breast cancer patients treated with whole breast RT. Balanced gradient echo MR images were acquired in four evenly spaced positions through the heart volume, in both sagittal and coronal planes, to quantify cardiac motion in the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) directions. Frame rates were approximately 6.5 and 3.5 frames per second for sagittal and coronal acquisitions respectively. Images were acquired continuously for 15-17 seconds for DIBH and for 61 seconds for FB. The heart was contoured and a SIFT-based tracking algorithm was used to map pixels from a reference image to each frame. The displacement of each pixel relative to its reference position was recorded for every frame. The mean displacements in the SI, AP, and RL directions were determined for each patient and for the cohort. In the treatment planning system, each patient’s observed mean displacement in the SI, AP, and RL directions was applied as an asymmetric expansion on the heart. The mean and max dose to this structure, representing the volume of the heart when accounting for intrafractional motion, were recorded for each patient. Results: Mean heart displacements in the R-L, S-I, and A-P directions are shown in Table 1, which summarizes the observed cardiac motion over 53,040 total frames.
Electronic Brachytherapy at the Time of Breast Conservation Surgery for Early-Stage Breast Cancer: Early Follow-Up Results of a Nonrandomized, Multicenter Trial A.N.M. Syed1 and D.J. Bourgeois III2; 1Long Beach Memorial Medical Center, Long Beach, CA, 2University of California Irvine, Orange, CA Purpose/Objective(s): To describe early follow-up results of a trial of single-fraction, intra-operative radiation therapy (IORT) delivered with an electronic brachytherapy system immediately following surgical resection for treatment of early-stage breast cancer. Materials/Methods: To date, 1,028 participants have been enrolled in this open label, single-arm, prospective, non-randomized trial at 28 hospitals in the USA (27) and Portugal (1). 1,023 participants with biopsy-proven ductal carcinoma in situ (DCIS) or invasive ductal carcinoma who met the inclusion criteria underwent lumpectomy followed by IORT to the lumpectomy cavity. A presterilized lead shield was placed on the chest wall and a balloon applicator suitable to the surgical bed was placed in the lumpectomy cavity and inflated with saline (30-75 cc). Balloon surface-to-skin distance of 1.0 cm was confirmed by ultrasound. Single-fraction IORT (20 Gy) was delivered at the balloon applicator surface with a mean radiation treatment time of 11.3 minutes. Following IORT, balloon was deflated and removed along with lead shielding, and surgical site was sutured. The prespecified primary outcome of this 10-year follow-up study is ipsilateral breast tumor recurrence at 5 years. Prespecified secondary outcomes include 10-year recurrence and cosmesis (Harvard Scale). Results: Median follow-up time was 1.2 years with 320, 102, and 10 participants completing 2-, 3-, and 4-year follow-up, respectively. Mean age at enrollment was 66 years (range 41-93). 246 participants had DCIS and 777 had invasive ductal carcinoma. DCIS nuclear grades were high (82), intermediate (119), or low (45) with three identified as bilateral. Invasive cancers were Grade 1 (318) including two bilateral cases, Grade 2 (340) with one bilateral case, Grade 3 (105) with two bilateral cases, or no Grade (14). Mean tumor size was 12.01 10.8 mm. Cosmesis was excellent in 100% of participants at 4-year followup and excellent to good in 94% and 91% of participants at 2- and 3year follow-up, respectively. The number of reported adverse events (AEs) that were Grade 2 or higher was 169 (9%). Seroma, breast induration, erythema, breast fibrosis, and breast pain were the most frequent AEs. There were ten deaths, none of which were breast cancer related. There were six ipsilateral breast recurrences and three new contralateral breast cancers. Conclusion: Single-fraction IORT using an electronic brachytherapy system following breast conservation surgery may be a promising treatment option for select early-stage breast cancer patients. Early findings from this multicenter trial suggest that the short and convenient course of radiation therapy has low morbidity, excellent to good cosmetic results, and a low rate of high-grade adverse events and recurrences. Author Disclosure: A.N. Syed: Independent Contractor; Long BEach Memorial Medical Center. Partner; Memorial Radiation Oncology Medical Group. D.J. Bourgeois: None.
Abstract 2117; Table 1
RL AP SI
DIBH, mm (±SD)
FB, mm (±SD)
5.5 1.1 5.0 1.3 7.6 2.5
7.9 1.2 7.1 1.4 14.0 2.5
The mean delivered dose to the heart was 161% of the planned dose. When accounting for motion, delivered mean dose to the heart on average in DIBH and FB increased by 82 and 176 cGy, respectively. Delivered Dmax to the heart increased by a mean of 716 cGy. Conclusion: The position of the heart is affected by respiratory and cardiac function, with greater motion observed in free-breathing than in DIBH. The greatest displacements were in the S-I direction, but displacements of dosimetric significance were noted in all three planes for both FB and DIBH. Therefore, treatment planning for thoracic RT which involves steep dosimetric gradients such as tangential beams or IMRT should take the expected cardiac motion into account during treatment planning. Author Disclosure: N. Daniel: None. H. Lashmett: None. T.R. Mazur: None. H.M. Gach: None. L.L. Ochoa: None. I. Zoberi: Employee; Washington University. M.A. Thomas: Employee; Saint Louis University.
2117
2118
Cardiac Motion Tracked on Cine MRI in Free-Breathing and Deep Inspiration Breath Hold: Effect on Dose Delivered to the Heart in Breast Cancer Patients N. Daniel, H. Lashmett, T.R. Mazur, H.M. Gach, L.L. Ochoa, I. Zoberi, and M.A. Thomas; Washington University School of Medicine, Department of Radiation Oncology, St. Louis, MO
Dosimetric Comparison Between 2D and 3D Treatment Planning in Breast Cancer When Using the RTOG Breast Contouring Atlas M. Thurman,1 P.N. Barry Jr,2 J. Gavin,1 R. Carter,1 M. Blackburn,3 J. Gaskins,1 and A.E. Dragun2; 1University of Louisville, Louisville, KY, 2 University of Louisville School of Medicine, Louisville, KY, 3University of Louisville, Louisville, KY, United States
Purpose/Objective(s): Cardiac toxicity is a well-recognized potential complication of thoracic radiation (RT), with recent studies demonstrating risk of cardiac injury that occurs with lower doses and at earlier timepoints than previously believed. Thus, an important goal of treatment planning is
Purpose/Objective(s): With the modernization of imaging techniques, radiation oncologists have moved from 2D-based treatment planning (2DTP) to 3D-based treatment planning (3DTP) for breast cancer. Target delineation for 3DTP is currently defined by the RTOG breast contouring
Volume 99 Number 2S Supplement 2017 atlas, and its use is mandated by current breast cancer protocols. We sought to assess differences in normal tissue dose and target coverage between 2DTP and 3DTP. Materials/Methods: We evaluated 2DTP and 3DTP for ten patients receiving left-sided whole breast radiation to 4256-5000cGy. Contours were retrospectively added to 2D plans. They included the breast CTV, PTV, and PTV_eval, as well as the heart and lung. All contours were delineated using the RTOG contouring atlases. Volumes were reviewed independently by two radiation oncologists who were not involved with the project. 3D plans were created such that 95% of the PTV_eval received 95% of the prescribed dose, and normal tissue constraints were per RTOG 1005. Results: On average, the mean heart dose was 889 cGy using 3DTP (range 448 - 1,560 cGy) versus 215 cGy using 2DTP (range 85 e 429 cGy). This represented a 674 cGy increase (CI: 458-890 cGy, p<0.0001). With 3DTP, 16% and 15% more cardiac tissue received 2000 and 2500 cGy respectively (CI V20: 11-20%, p<0.0001; CI V25: 10-20%, p<0.0001). 3DTP results in a mean lung dose that is significantly higher (Mean: 726 cGy, CI 584-869 cGy, p<0.0001). Additionally, significantly more ipsilateral lung tissue was treated using 3DTP (V5 increased by 19% CI: 15-23%, p<0.0001; V10 increased by 18%, CI 15-20%, p<0.0001; V20increased by 18%, CI: 15-21%, p<0.0001). There was a significant increase in volume size when RTOG contours were used (95% Isodose line (IDL) mean: 34%, CI 58-70%, p<0.0001; 90% IDL mean 35%, CI 59-69%, p<0.0001)).This resulted in significantly more breast tissue treated (95% IDL mean: 552cc, CI: 378-725cc, p<0.0001; 90% IDL mean: 688cc, CI 90% 511-865cc, p<0.0001). Conclusion: Treatment planning using the recommended RTOG contours results in significantly more dose delivered to both the breast and normal tissue. This difference will result in increased toxicity without proof of increased efficacy. Significant adjustments to the published contouring guidelines are strongly recommended. Author Disclosure: M. Thurman: None. P.N. Barry: I only receive my base salary. I do not receive additional compensation.; Radiation Oncology, UofL SOM. J. Gavin: None. R. Carter: None. M. Blackburn: None. J. Gaskins: None. A.E. Dragun: None.
2119 Prognostic Value of HER2 Status in Breast Cancer Patients With Brain Metastases S. Tsuruoka,1 M. Kataoka,1 K. Uwatsu,1 A. Nishikawa,1 and T. Mochizuki2; 1Dept. of Radiation Oncology, Shikoku Cancer Center, Matsuyama, Japan, 2Dept. of Radiology, Ehime University Hospital, Toon, Japan Purpose/Objective(s): To develop tailor-made treatment for brain metastases (BM) from breast cancer, prognostic factors should be examined according to subtypes of breast cancer. In this study, prognostic factors for BM from breast cancer received radiotherapy (RT) were assessed with a focus on the human epidermal growth factor receptor type 2 (HER2) status. Materials/Methods: From April 2006 to December 2014, 137 female patients received RT for intracranial metastases from breast cancer. After exclusion of patients whose extracranial lesions were only bone metastases and patients who had meningeal metastases, 100 patients were analyzed in this study. The primary outcome was overall survival (OS). OS was calculated from the start of RT for BM. Results: The median age was 60 years old (32 to 87). The median followup time after the start of treatment for BM was 8.3 months (0.4 to 87.8 months). For BM, 73 patients received whole-brain RT (WBRT) alone, 24 patients received stereotactic radiosurgery (SRS) alone, two patients received WBRT combined with SRS, and one patient received surgical resection plus postoperative WBRT. The numbers of patients with HER2positive, HER2-negative, and HER2 status unknown were 34, 63 and 3, respectively. All HER2-positive patients were treated with Trastuzumab with or without lapatinib, pertuzumab and/or trastuzumab emtansine. The median OS was 8.7 months for all patients. On univariate analysis for OS,
Poster Viewing
E51
HER2 status, triple negative, extracranial active lesions, and performance status (PS) were statistically significant factors (pZ0.006, pZ0.010, pZ0.005, and p<0.001, respectively). OS of HER2-positive patients was longer with statistical significance compared to HER2-negtive patients (median 15.8 vs 6.4 months; pZ0.010). On multivariate analysis, HER2positive (hazard ratio (HR) 0.56 ; 95% confident interval (CI)Z0.33-0.92 ; pZ0.023) and good PS (HR 0.31 ; 95%CIZ0.19-0.50 ; p<0.001) were independently associated with better OS. On multivariate analysis, triple negative (HR 1.91 ; 95%CIZ1.07-3.31 ; pZ0.029), and extracranial active lesion (HR 1.91 ; 95%CIZ1.14-3.36 ; pZ0.013) were independently associated with worse OS. Conclusion: Patients with HER2-positive breast cancer showed favorable prognosis after RT for BM. It seemed that BM from HER2-positive breast cancer should be treated with RT aggressively. Author Disclosure: S. Tsuruoka: None. M. Kataoka: None. K. Uwatsu: None. A. Nishikawa: None. T. Mochizuki: None.
2120 Effect of Margin Status on 10-Year Local Recurrence and Survival Outcomes in a Large Population-Based Analysis of Women Treated With Breast-Conserving Therapy S.A. Tyler,1 P. Truong,1 M. Lesperance,2 A. Nichol,3 C. Baliski,4 R. Warburton,5 and S.K. Tyldesley6; 1British Columbia Cancer Agency, Victoria, BC, Canada, 2University of Victoria, Victoria, BC, Canada, 3BC Cancer Agency, Vancouver, BC, Canada, 4British Columbia Cancer Agency, Kelowna, BC, Canada, 5University of British Columbia, Vancouver, BC, Canada, 6British Columbia Cancer Agency, Vancouver, BC, Canada Purpose/Objective(s): A 2014 SS0/ASTRO consensus statement suggests “no ink on tumor” is a sufficient surgical margin for invasive breast cancer treated with breast conserving surgery (BCS). Whether long-term outcomes in cases with close margin <2mm are inferior to cases with clear margins >2mm remains controversial. This study evaluates 10-year outcomes by margin status in a population-based cohort of women treated with BCS and adjuvant radiotherapy (RT). Materials/Methods: Subjects were 10,863 women with pT1-T3, any N, M0 invasive breast cancer referred from July 1, 2001 to Dec. 31, 2011, an era in which re-excision was generally used for close or positive margins. Data on margin location was available in a subset of 2381 cases referred from Jan. 1, 2010 to Dec. 31, 2011. All women underwent BCS and adjuvant whole breast boost RT (boost RT generally used for close or positive final margins or age < 50). Ten-year local recurrence (LR), and breast cancer-specific survival (BCSS) were examined using Kaplan-Meier (KM) and competing risk analysis in cohorts with negative (>2mm; nZ9241, 85%), close (2mm; nZ1310, 12%), or positive (tumor touching ink; nZ312, 3%) margins. Competing risk multivariable analysis (MVA) was performed using Fine and Gray modeling. Matched-pair analysis compared LR and BCSS between close/positive cases matched to negative margin controls. Results: Median follow-up was 8 years. Systemic therapy was used in 87% of patients. Boost RT was used in 34.1%, 76.9% and 79.5% of patients with negative, close, and positive margins, respectively. In the negative, close, and positive margin cohorts, 10-year KM outcomes were: LR 2.8%, 4.3%, and 4.0% and BCSS 93.7%, 91.5%, and 87.4%, respectively. On competing risk MVA, close margins were not significantly associated with either increased LR (HR 1.25, 95% CI 0.79-1.97, pZ0.35) or reduced BCSS (HR 1.25, 95% CI 0.98-1.58, pZ0.07) relative to negative margins. Age <45, grade 3, 4 positive nodes, and no systemic therapy were factors associated with both increased LR and reduced BCSS. On MVA, use of boost RT was not associated with LR (pZ0.92) or BCSS (pZ0.30). On matched-pair analysis, close margin cases had similar LR (pZ0.11) and BCSS (pZ0.10) compared to negative margin controls. Among the 554 cases with close or positive margins from 2010-2011 in whom data on margin location were available, 57% were anterior or posterior, so these
International Journal of Radiation Oncology Biology Physics
2116
to minimize dose delivered to the heart. However, treatment planning assumes a static position of the heart on simulation CT. We hypothesized that variation in heart position during RT delivery due to normal respiratory and cardiac function impacts the dose delivered to the heart and that the delivered dose is significantly different from the planned dose. We conducted a study utilizing cine MRI to quantify cardiac motion and to determine its dosimetric impact. Materials/Methods: Cine MR images (1.5T) were acquired in both freebreathing (FB) and deep inspiration breath hold (DIBH) for 9 healthy volunteers and 8 breast cancer patients treated with whole breast RT. Balanced gradient echo MR images were acquired in four evenly spaced positions through the heart volume, in both sagittal and coronal planes, to quantify cardiac motion in the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) directions. Frame rates were approximately 6.5 and 3.5 frames per second for sagittal and coronal acquisitions respectively. Images were acquired continuously for 15-17 seconds for DIBH and for 61 seconds for FB. The heart was contoured and a SIFT-based tracking algorithm was used to map pixels from a reference image to each frame. The displacement of each pixel relative to its reference position was recorded for every frame. The mean displacements in the SI, AP, and RL directions were determined for each patient and for the cohort. In the treatment planning system, each patient’s observed mean displacement in the SI, AP, and RL directions was applied as an asymmetric expansion on the heart. The mean and max dose to this structure, representing the volume of the heart when accounting for intrafractional motion, were recorded for each patient. Results: Mean heart displacements in the R-L, S-I, and A-P directions are shown in Table 1, which summarizes the observed cardiac motion over 53,040 total frames.
Electronic Brachytherapy at the Time of Breast Conservation Surgery for Early-Stage Breast Cancer: Early Follow-Up Results of a Nonrandomized, Multicenter Trial A.N.M. Syed1 and D.J. Bourgeois III2; 1Long Beach Memorial Medical Center, Long Beach, CA, 2University of California Irvine, Orange, CA Purpose/Objective(s): To describe early follow-up results of a trial of single-fraction, intra-operative radiation therapy (IORT) delivered with an electronic brachytherapy system immediately following surgical resection for treatment of early-stage breast cancer. Materials/Methods: To date, 1,028 participants have been enrolled in this open label, single-arm, prospective, non-randomized trial at 28 hospitals in the USA (27) and Portugal (1). 1,023 participants with biopsy-proven ductal carcinoma in situ (DCIS) or invasive ductal carcinoma who met the inclusion criteria underwent lumpectomy followed by IORT to the lumpectomy cavity. A presterilized lead shield was placed on the chest wall and a balloon applicator suitable to the surgical bed was placed in the lumpectomy cavity and inflated with saline (30-75 cc). Balloon surface-to-skin distance of 1.0 cm was confirmed by ultrasound. Single-fraction IORT (20 Gy) was delivered at the balloon applicator surface with a mean radiation treatment time of 11.3 minutes. Following IORT, balloon was deflated and removed along with lead shielding, and surgical site was sutured. The prespecified primary outcome of this 10-year follow-up study is ipsilateral breast tumor recurrence at 5 years. Prespecified secondary outcomes include 10-year recurrence and cosmesis (Harvard Scale). Results: Median follow-up time was 1.2 years with 320, 102, and 10 participants completing 2-, 3-, and 4-year follow-up, respectively. Mean age at enrollment was 66 years (range 41-93). 246 participants had DCIS and 777 had invasive ductal carcinoma. DCIS nuclear grades were high (82), intermediate (119), or low (45) with three identified as bilateral. Invasive cancers were Grade 1 (318) including two bilateral cases, Grade 2 (340) with one bilateral case, Grade 3 (105) with two bilateral cases, or no Grade (14). Mean tumor size was 12.01 10.8 mm. Cosmesis was excellent in 100% of participants at 4-year followup and excellent to good in 94% and 91% of participants at 2- and 3year follow-up, respectively. The number of reported adverse events (AEs) that were Grade 2 or higher was 169 (9%). Seroma, breast induration, erythema, breast fibrosis, and breast pain were the most frequent AEs. There were ten deaths, none of which were breast cancer related. There were six ipsilateral breast recurrences and three new contralateral breast cancers. Conclusion: Single-fraction IORT using an electronic brachytherapy system following breast conservation surgery may be a promising treatment option for select early-stage breast cancer patients. Early findings from this multicenter trial suggest that the short and convenient course of radiation therapy has low morbidity, excellent to good cosmetic results, and a low rate of high-grade adverse events and recurrences. Author Disclosure: A.N. Syed: Independent Contractor; Long BEach Memorial Medical Center. Partner; Memorial Radiation Oncology Medical Group. D.J. Bourgeois: None.
Abstract 2117; Table 1
RL AP SI
DIBH, mm (±SD)
FB, mm (±SD)
5.5 1.1 5.0 1.3 7.6 2.5
7.9 1.2 7.1 1.4 14.0 2.5
The mean delivered dose to the heart was 161% of the planned dose. When accounting for motion, delivered mean dose to the heart on average in DIBH and FB increased by 82 and 176 cGy, respectively. Delivered Dmax to the heart increased by a mean of 716 cGy. Conclusion: The position of the heart is affected by respiratory and cardiac function, with greater motion observed in free-breathing than in DIBH. The greatest displacements were in the S-I direction, but displacements of dosimetric significance were noted in all three planes for both FB and DIBH. Therefore, treatment planning for thoracic RT which involves steep dosimetric gradients such as tangential beams or IMRT should take the expected cardiac motion into account during treatment planning. Author Disclosure: N. Daniel: None. H. Lashmett: None. T.R. Mazur: None. H.M. Gach: None. L.L. Ochoa: None. I. Zoberi: Employee; Washington University. M.A. Thomas: Employee; Saint Louis University.
2117
2118
Cardiac Motion Tracked on Cine MRI in Free-Breathing and Deep Inspiration Breath Hold: Effect on Dose Delivered to the Heart in Breast Cancer Patients N. Daniel, H. Lashmett, T.R. Mazur, H.M. Gach, L.L. Ochoa, I. Zoberi, and M.A. Thomas; Washington University School of Medicine, Department of Radiation Oncology, St. Louis, MO
Dosimetric Comparison Between 2D and 3D Treatment Planning in Breast Cancer When Using the RTOG Breast Contouring Atlas M. Thurman,1 P.N. Barry Jr,2 J. Gavin,1 R. Carter,1 M. Blackburn,3 J. Gaskins,1 and A.E. Dragun2; 1University of Louisville, Louisville, KY, 2 University of Louisville School of Medicine, Louisville, KY, 3University of Louisville, Louisville, KY, United States
Purpose/Objective(s): Cardiac toxicity is a well-recognized potential complication of thoracic radiation (RT), with recent studies demonstrating risk of cardiac injury that occurs with lower doses and at earlier timepoints than previously believed. Thus, an important goal of treatment planning is
Purpose/Objective(s): With the modernization of imaging techniques, radiation oncologists have moved from 2D-based treatment planning (2DTP) to 3D-based treatment planning (3DTP) for breast cancer. Target delineation for 3DTP is currently defined by the RTOG breast contouring
Volume 99 Number 2S Supplement 2017 atlas, and its use is mandated by current breast cancer protocols. We sought to assess differences in normal tissue dose and target coverage between 2DTP and 3DTP. Materials/Methods: We evaluated 2DTP and 3DTP for ten patients receiving left-sided whole breast radiation to 4256-5000cGy. Contours were retrospectively added to 2D plans. They included the breast CTV, PTV, and PTV_eval, as well as the heart and lung. All contours were delineated using the RTOG contouring atlases. Volumes were reviewed independently by two radiation oncologists who were not involved with the project. 3D plans were created such that 95% of the PTV_eval received 95% of the prescribed dose, and normal tissue constraints were per RTOG 1005. Results: On average, the mean heart dose was 889 cGy using 3DTP (range 448 - 1,560 cGy) versus 215 cGy using 2DTP (range 85 e 429 cGy). This represented a 674 cGy increase (CI: 458-890 cGy, p<0.0001). With 3DTP, 16% and 15% more cardiac tissue received 2000 and 2500 cGy respectively (CI V20: 11-20%, p<0.0001; CI V25: 10-20%, p<0.0001). 3DTP results in a mean lung dose that is significantly higher (Mean: 726 cGy, CI 584-869 cGy, p<0.0001). Additionally, significantly more ipsilateral lung tissue was treated using 3DTP (V5 increased by 19% CI: 15-23%, p<0.0001; V10 increased by 18%, CI 15-20%, p<0.0001; V20increased by 18%, CI: 15-21%, p<0.0001). There was a significant increase in volume size when RTOG contours were used (95% Isodose line (IDL) mean: 34%, CI 58-70%, p<0.0001; 90% IDL mean 35%, CI 59-69%, p<0.0001)).This resulted in significantly more breast tissue treated (95% IDL mean: 552cc, CI: 378-725cc, p<0.0001; 90% IDL mean: 688cc, CI 90% 511-865cc, p<0.0001). Conclusion: Treatment planning using the recommended RTOG contours results in significantly more dose delivered to both the breast and normal tissue. This difference will result in increased toxicity without proof of increased efficacy. Significant adjustments to the published contouring guidelines are strongly recommended. Author Disclosure: M. Thurman: None. P.N. Barry: I only receive my base salary. I do not receive additional compensation.; Radiation Oncology, UofL SOM. J. Gavin: None. R. Carter: None. M. Blackburn: None. J. Gaskins: None. A.E. Dragun: None.
2119 Prognostic Value of HER2 Status in Breast Cancer Patients With Brain Metastases S. Tsuruoka,1 M. Kataoka,1 K. Uwatsu,1 A. Nishikawa,1 and T. Mochizuki2; 1Dept. of Radiation Oncology, Shikoku Cancer Center, Matsuyama, Japan, 2Dept. of Radiology, Ehime University Hospital, Toon, Japan Purpose/Objective(s): To develop tailor-made treatment for brain metastases (BM) from breast cancer, prognostic factors should be examined according to subtypes of breast cancer. In this study, prognostic factors for BM from breast cancer received radiotherapy (RT) were assessed with a focus on the human epidermal growth factor receptor type 2 (HER2) status. Materials/Methods: From April 2006 to December 2014, 137 female patients received RT for intracranial metastases from breast cancer. After exclusion of patients whose extracranial lesions were only bone metastases and patients who had meningeal metastases, 100 patients were analyzed in this study. The primary outcome was overall survival (OS). OS was calculated from the start of RT for BM. Results: The median age was 60 years old (32 to 87). The median followup time after the start of treatment for BM was 8.3 months (0.4 to 87.8 months). For BM, 73 patients received whole-brain RT (WBRT) alone, 24 patients received stereotactic radiosurgery (SRS) alone, two patients received WBRT combined with SRS, and one patient received surgical resection plus postoperative WBRT. The numbers of patients with HER2positive, HER2-negative, and HER2 status unknown were 34, 63 and 3, respectively. All HER2-positive patients were treated with Trastuzumab with or without lapatinib, pertuzumab and/or trastuzumab emtansine. The median OS was 8.7 months for all patients. On univariate analysis for OS,
Poster Viewing
E51
HER2 status, triple negative, extracranial active lesions, and performance status (PS) were statistically significant factors (pZ0.006, pZ0.010, pZ0.005, and p<0.001, respectively). OS of HER2-positive patients was longer with statistical significance compared to HER2-negtive patients (median 15.8 vs 6.4 months; pZ0.010). On multivariate analysis, HER2positive (hazard ratio (HR) 0.56 ; 95% confident interval (CI)Z0.33-0.92 ; pZ0.023) and good PS (HR 0.31 ; 95%CIZ0.19-0.50 ; p<0.001) were independently associated with better OS. On multivariate analysis, triple negative (HR 1.91 ; 95%CIZ1.07-3.31 ; pZ0.029), and extracranial active lesion (HR 1.91 ; 95%CIZ1.14-3.36 ; pZ0.013) were independently associated with worse OS. Conclusion: Patients with HER2-positive breast cancer showed favorable prognosis after RT for BM. It seemed that BM from HER2-positive breast cancer should be treated with RT aggressively. Author Disclosure: S. Tsuruoka: None. M. Kataoka: None. K. Uwatsu: None. A. Nishikawa: None. T. Mochizuki: None.
2120 Effect of Margin Status on 10-Year Local Recurrence and Survival Outcomes in a Large Population-Based Analysis of Women Treated With Breast-Conserving Therapy S.A. Tyler,1 P. Truong,1 M. Lesperance,2 A. Nichol,3 C. Baliski,4 R. Warburton,5 and S.K. Tyldesley6; 1British Columbia Cancer Agency, Victoria, BC, Canada, 2University of Victoria, Victoria, BC, Canada, 3BC Cancer Agency, Vancouver, BC, Canada, 4British Columbia Cancer Agency, Kelowna, BC, Canada, 5University of British Columbia, Vancouver, BC, Canada, 6British Columbia Cancer Agency, Vancouver, BC, Canada Purpose/Objective(s): A 2014 SS0/ASTRO consensus statement suggests “no ink on tumor” is a sufficient surgical margin for invasive breast cancer treated with breast conserving surgery (BCS). Whether long-term outcomes in cases with close margin <2mm are inferior to cases with clear margins >2mm remains controversial. This study evaluates 10-year outcomes by margin status in a population-based cohort of women treated with BCS and adjuvant radiotherapy (RT). Materials/Methods: Subjects were 10,863 women with pT1-T3, any N, M0 invasive breast cancer referred from July 1, 2001 to Dec. 31, 2011, an era in which re-excision was generally used for close or positive margins. Data on margin location was available in a subset of 2381 cases referred from Jan. 1, 2010 to Dec. 31, 2011. All women underwent BCS and adjuvant whole breast boost RT (boost RT generally used for close or positive final margins or age < 50). Ten-year local recurrence (LR), and breast cancer-specific survival (BCSS) were examined using Kaplan-Meier (KM) and competing risk analysis in cohorts with negative (>2mm; nZ9241, 85%), close (2mm; nZ1310, 12%), or positive (tumor touching ink; nZ312, 3%) margins. Competing risk multivariable analysis (MVA) was performed using Fine and Gray modeling. Matched-pair analysis compared LR and BCSS between close/positive cases matched to negative margin controls. Results: Median follow-up was 8 years. Systemic therapy was used in 87% of patients. Boost RT was used in 34.1%, 76.9% and 79.5% of patients with negative, close, and positive margins, respectively. In the negative, close, and positive margin cohorts, 10-year KM outcomes were: LR 2.8%, 4.3%, and 4.0% and BCSS 93.7%, 91.5%, and 87.4%, respectively. On competing risk MVA, close margins were not significantly associated with either increased LR (HR 1.25, 95% CI 0.79-1.97, pZ0.35) or reduced BCSS (HR 1.25, 95% CI 0.98-1.58, pZ0.07) relative to negative margins. Age <45, grade 3, 4 positive nodes, and no systemic therapy were factors associated with both increased LR and reduced BCSS. On MVA, use of boost RT was not associated with LR (pZ0.92) or BCSS (pZ0.30). On matched-pair analysis, close margin cases had similar LR (pZ0.11) and BCSS (pZ0.10) compared to negative margin controls. Among the 554 cases with close or positive margins from 2010-2011 in whom data on margin location were available, 57% were anterior or posterior, so these