Abstract BACKGROUND: Breast cancer and its treatments produce multiple symptoms that significantly impact patient quality of life (QOL). Distress and impaired function are the most commonly referred symptoms [Cleeland CS, 2007]. Routine cancer care assessment of patient-reported outcomes (PROs), including symptoms, function, and QOL, has been shown to improve symptom management, identification of psychosocial problems, and patient-provider communication. The Symptom Inventory Tool (SIT) is an assessment tool that captures the patients' perceived symptom burden for real-time clinical intervention, taken at the point of no intervention (baseline) and every 21 days or greater. The SIT is comprised of 27 questions utilizing the M.D. Anderson Symptom Inventory tool (MDASI) [Cleeland CS, Cancer 2013], and validated assessment instrument with 8 questions added and a free text box by Cancer Treatment Centers of America (CTCA). CTCA is a national network of five hospitals that specialize in cancer treatment and integrative oncology. PATIENTS & METHODS: Patients reported symptoms intensity using 19-item MD Anderson Symptom Inventory (MDASI) and 8 additional questions created by CTCA (constipation, swelling, mouth soreness, bleeding, sexual interest, family, hope & QOL). Symptoms were rated "at the worst" on an 11-point numeric scale ranging from 0 ('no present") to 10 ("as bad as you can imagine") in the previous 24 hours. SIT became an integral part of patient care at CTCA beginning in 2012. RESULTS: From July 2012 to February 2015, a total of 3,740 outpatients with breast cancer were evaluated at CTCA. A total of 13,852 assessments were analyzed. The assessments consisted of 3,513 completed at baseline, 2,237 completed at the 2nd follow up (FU), and 8,014 completed at 3rd FU or greater. Median age was 50 (range, 17-88), 60% of patients were ER+. Race: White (68%), Black (29%), and other (3%). Disease extension: locoregional (86%) and metastatic (13.6%). The average time since cancer was diagnosed were 35 months, and 50.7% of the patients received prior systemic therapy: chemotherapy (55%), hormone-therapy (41%), and immunotherapy (4%). Mean, standard deviation and inter quartile ranges at baseline assessment are depicted in. Table 1.Patient Reported SymptomBaseline assessment statisticsPercentage of patients with severe symptoms at baseline and reporting a clinically significant change (2 points) at 2nd SIT assessment Mean +/- STDInterquartile range (IQR)Significant decreaseNo changeDistress3.0 +/- 3.0[0.5]695 (31.3%)594 (26.8%)414 (18.7%)Sadness2.5 +/- 2.9[0.4]622 (28%)718 (32.3%)358 (16.1%)Disturbed Sleep3.3 +/- 3.2[0.6]550 (24.8%)517 (23.3%)642 (28.9%)Mood2.6 +/- 2.7[0.4]549 (24.7%)678 (30.5%)447 (20.1%)Pain2.7 +/- 3.0[0.5]523 (23.9%)675 (30.8%)519 (23.7%)*IQR is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rank-ordered data set into four equal parts CONCLUSIONS: The SIT was successful in identifying symptoms burden and interference with life issues in breast cancer patients. Distress, sadness, disturbed sleep, mood and pain were the most common reported symptoms. Early identification of patient burden symptoms allowed immediate intervention and improvement in approximately a quarter of patients. Citation Format: Alvarez RH, Hartman S, Bosch B, Kendrick D, Cohen L, Fridman J, Ottersen D, Walcott K, Ware S, Castro I, Thomas J, Niu J, Ahn E, Denny D, Markman M. Self-reported symptoms and interference issues in breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-10-27.