Background: Many studies have shown that fatigue is associated with poor outcomes such as quality of life and physical function in breast cancer survivors.Early treatment of symptoms that result in persistent fatigue may be a strategy to mitigate long-term fatigue.As a result, we studied symptoms and developed risk estimates for patients that are most likely to develop fatigue by pre-surgery and follow up among patients treated on the I-SPY 2 neoadjuvant trial. I-SPY 2 is a phase-II adaptive trial for high-risk early-stage breast cancer patients. Methods: In this retrospective cohort study of 306 women undergoing neoadjuvant chemotherapy +/- targeted therapy, patients complete electronic surveys of symptoms via 34 PRO-CTCAE items and QOL via 9 PROMIS instruments. Fatigue is collected as part of the PROMIS survey and scored using Health Measures. Study timepoints are screening (SC), weekly study treatment (ST), 12 weeks (12w), pre-surgery (PS) and at 1, 6, 12 and 24 months (FU1-FU4) following surgery. Correlation between symptoms and fatigue at equal timepoints was quantified using spearman correlations and BH-adjusted p-values. For symptom odds analysis, symptoms were binarized such that those that had an average grade of mild or above (severity), rarely or above (frequency) or a little bit or above (interference) between ST weeks 1-6 were considered present. Clinically significant (CS) increase in fatigue was defined as an increase >=0.5 standard deviation (SD) in mean from baseline. Logistic regression was used to determine odds ratios of factors associated with fatigue. Results: Baseline PROMIS fatigue mean score was 47.14 (SD 9.31) with a median of 47.45. A CS increase in fatigue from baseline was seen in 55% of patients at 12w, and 61% of patients pre-surgery. Of the patients that had a CS increase in fatigue at any point prior to surgery, 45.7% had persistent fatigue through FU1-4. Symptoms associated with Fatigue at 12w were shortness of breath, headache, and nausea (P< 0.03). At PS, fatigue was significantly correlated with GI symptoms, neuropathy, and shortness of breath (P< 0.03). Risk estimates for patients that filled out symptom surveys at early timepoints (weeks 1-6) and also had fatigue were evaluated. Patients with early GU (genitourinary) symptoms had higher risk of fatigue at IR (OR=9.33, p=0.02, 88.9% in cases vs 33.3% in controls). Patients with early GI symptoms at PS (OR=8.56, p=0.03, 90.1% vs 50%), or FU2-4 (OR= 5.88 and 7.36, p= 0.04 and 0.02, 80% vs 39.1% and 81.8% vs 36.3%) also had a higher risk of developing fatigue. Conclusions: A CS increase in fatigue during treatment and follow up is seen in the majority of patients and is associated with a large number of persistent symptoms.