Background: Cognitive decline related to cancer and its treatments is a common concern among patients receiving treatment for cancer. Routine cognitive screening in oncology practice has been limited by the absence of a reliable, cancer-specific cognitive test. The Blessed Orientation Memory Concentration Test (BOMC) [1], has been incorporated in cancer-specific geriatric assessments, but there is no established cutpoint for cancer-related cognitive impairment. Recent research suggests that BOMC scores ≥ 5 may represent cognitive impairment in older patients with cancer. The purpose of this study was to identify cognitive impairment and associated characteristics in chemotherapy-naïve patients with breast cancer. Methods: Women with stage I-III breast cancer were recruited between 2009 and 2018. The BOMC (range 0-28, higher is worse function) was administered prior to chemotherapy. Associations between cognitive dysfunction (BOMC ≥ 5) and functional, psychosocial, medical variable were assessed using log binomial regression analysis. Results: In a sample of 331 women with breast cancer, the mean age was 65.2 years and 68.6% were 65 and older. Twenty-seven percent demonstrated cognitive impairment prior to treatment. Patients with Time Up and Go Test (TUG) ≥ 14 had increased risk of cognitive impairment compared to those with TUG < 14 (44% vs. 23%, p = 0.0002). After controlling for demographic factors, the estimated increase in risk was 66% (RR: 1.66, 95% CI (1.20, 2.31), p = 0.002). For Medical Outcomes Survey (MOS) Physical Function, after controlling for demographic factors, each 1 point increase in physical function (range 0-20, higher is better function) was associated with a 5% decrease in risk of cognitive impairment (p = 0.0004). Conclusions: Using a newly proposed BOMC cutpoint of ≥ 5, our study identified cognitive impairment in over 25% of older, chemotherapy naïve women with breast cancer. This is similar to what has been reported using rigorous neuropsychological testing in comparable populations. Additionally, we found that this degree of cognitive dysfunction was associated with both patient-reported and clinician-assessed impairment in physical function, further supporting the clinical relevance of this new cutpoint. Reference: [1] Katzman et al. Am. J. Psychiatry. 140 (1983) 734–739.