Materials/Methods: We sent a survey to radiation oncologists of 200 institutions in Japan and received the answers from 92 institutes (46%). Among them, 24 institutions (26%) had some experiences of the ISR matched to the previous irradiated area and the details of the cases were available in 16 patients from 11 institutions. These 16 cases were analyzed in this study. Results: Eight patients were after breast conserving therapy (group A) and another 8 patients were after post mastectomy radiotherapy (PMRT) (group B). The postoperative pathology showed positive axillary lymph nodes in 7/8, 8/8 patients, positive lymphatic invasion in 4/7, 6/6 patients, negative ER in 6/7, 5/6 patients in group A and group B respectively. Total doses of post- operative radiotherapy were 48-60Gy (median 50Gy) in group A and 50-51Gy (median 50Gy) in group B. The time periods between the completion of radiotherapy and the occurrence of ISR were 1-27 months (median 3.5) in group A and 2-33 months (median 8.5) in group B. Four patients had preceding local or distant recurrence. All patients subsequently developed distant metastases. All patients in group A died of disease in 3-16 months whereas 4/8 patients in group B survived in 14-67 months after the occurrence of ISR. Median survival time were 266 days in group A and 1105 days in group B (p = 0.0001). Conclusions: Patients who developed ISR corresponding to the previously irradiated area tended to have several characteristics including positive lymph nodes metastases, intensive lymphatic invasion, and negative ER. All cases developed distant metastases subsequently and prognoses were dismal. However, in some patients after PMRT, longer survival was sometimes obtained with salvage therapy. We should be aware of this rare type recurrence in breast cancer patients after postoperative radiotherapy especially with these characteristics. Author Disclosure: K. Tsujino, None; K. Kashihara, None; S. Kotani, None; K. Imanaka, None; Y. Takada, None; T. Uno, None; H. Hirata, None; Y. Kaneyasu, None; K. Sekiguchi, None; E. Ogo, None. 2079 Locoregional Recurrence in Patients with Triple-negative Breast Cancer: The Impact of Radiotherapy A. E. Dragun, J. Pan, D. Jain, B. Kruse, S. Rai University of Louisville, James Graham Brown Cancer Center, Louisville, KY Purpose/Objective(s): To examine the impact of radiotherapy on breast cancer patients with triple negative (ER-, PR-, Her2/neu -) disease. Materials/Methods: A prospectively collected database of 110 triple negative breast cancer patients was initiated at the University of Louisville in 2004. Fifty-two patients who had all phases of their therapy (surgery, chemotherapy, and radiotherapy) at the Brown Cancer Center with a minimum of two months follow-up are included in this analysis. Patients with all types of surgery (lumpectomy or mastectomy), chemotherapy (different drug regimens, neoadjuvant or adjuvant), and radiation therapy (tangents only or comprehensive nodal irradiation) are included. Patients received radiotherapy in the setting of breast-conservation and in the post-mastectomy setting for $ 5cm primary tumors and/or $ 4 positive lymph nodes. Patients were divided into two groups for statistical analysis, based on whether they received radiotherapy or not. These groups were compared in terms of locoregional control and breast cancer specific survival. Results: In the analyzed cohort of 52 patients, 37 (71%) received radiation therapy as part of their treatment regimen, and 15 (29%) received no radiotherapy. Regarding demographics, the median age was 50 years (range: 31-79y); 52% of patients were white, 44% were black; 58% were smokers; and 27% had a family history of breast cancer. The median follow-up in months from the com- pletion of treatment is 19.7 (range: 2.0-48.0). For the entire group, overall 1-, 2- 3- and 4- year survivals (OS) from the completion of the treatment are 92%, 87%, 87%, and 58%, respectively. Of the patients who received radiation therapy, 25 (68%) did so in the setting of breast conservation. Patients who received radiation therapy were significantly more likely to be of a higher T-stage (p \0.001) and N-stage (p \0.001) than patients who did not receive radiotherapy. The 4-year actuarial locoregional relapse-free survival (LRFS) probability for patients who received radiation is much higher than those who did not receive radiation (66.1% vs. 29.5%, p = 0.016). Conclusions: Despite their significantly lower T- and N-stage, patients with triple-negative breast cancer who do not undergo radiation therapy have a significantly higher locoregional recurrence. Triple-negative status should be considered a factor in offer- ing postmastectomy radiotherapy. This study is limited due to its small sample size and these findings should be confirmed by a larger, multi-institutional study. Author Disclosure: A.E. Dragun, Hologic, D. Speakers Bureau/Honoraria; J. Pan, None; D. Jain, None; B. Kruse, None; S. Rai, None. 2080 Survival and Local Control after Irradiation in Young Patients with Breast Cancer X. Sanz 1 , 2 , N. Rodriguez 1,2 , P. Foro 1,2 , M. Lacruz 1,2 , A. Reig 1 , J. Quera 1,2 , J. Lozano 1 , I. Membrive 1 , E. Ferna ´ndez-Velilla 1 , M. Algara 1,2 1 Radiation Oncology Department, Barcelona, Spain, 2 Universitat Pompeu Fabra, Barcelona, Spain Purpose/Objective(s): Breast cancer in young patients is often associated with poorer prognosis. We analyze local control and survival with adjuvant radiation in a series of patients 40 years or younger after breast-conserving therapy or mastectomy in order to determine the better approach according to stage, performed surgery or prognostic factors. Materials/Methods: Data for 176 breast cancers in 175 young patients were reviewed. Mean age was 36.3 years. Almost all patients were premenopausal (97.7%). Surgery consisted in lumpectomy or quadrantectomy in 127 cases (72.1%) and mastectomy in the remaining 49 (27.9%). Axillary lymph node dissection was performed in 87.6% or sentinel lymph node biopsy only in 7.4% of cases. Intraductal carcinoma was present in 51.1% of cases (17.6% of them with comedocarcinoma). Hormonal receptors were known in 82% of patients, and 58.5% of them were positive. The radiation dose to the whole breast after breast conserving surgery was 47 Gy (40-52) at standard fractionation and with boost doses of 9-25 Gy administered to the tumor bed in 88% of cases. After mastectomy doses to chest wall and nodal areas was 50 Gy (40-71). Results: Median follow-up for all patients was 5 years. Local relapse (ipsilateral breast tumour or regional recurrence), and distant metastasis occurred in 13 (7.4%), and 27 patients (15.3%), respectively. The 5-year overall survival and disease-free survival rates S216 I. J. Radiation Oncology d Biology d Physics Volume 75, Number 3, Supplement, 2009