Background: Depression and anxiety are frequent causes of excess morbidity for cancer patients, but access to mental health care, including outpatient psychiatry, is limited across academic and community settings. The Collaborative Care Model (CoCM) is a team-based model of care that is proven to leverage limited mental health resources across a wider population in primary care (Raney L, Am J Psychiatry, 2015). Evidence suggests that CoCM can be effectively applied to cancer populations too (Walker J, Gen Hosp Psychiatry, 2009). Methods: The investigators adapted CoCM to treat depression and anxiety in an academic BC clinic. A quality protocol was approved by the institutional board. All English-speaking BC patients were screened for depression using the PHQ-2 and PHQ-9. Patients with PHQ-9 ≥15 or clinical suspicion of severe anxiety or depression were referred to CoCM. The CoCM intervention included social work care management and regular case reviews by a psychiatrist. Medical oncologists prescribed all psychiatric medications. Patients were referred to mental health services in the community as needed. Results: From November 2018 through January 2020, a total of 74 patients were enrolled in CoCM. Median age was 50 years (range: 28-74 years) with BC stages I-III (n = 49, 66.2%) and stage IV (n = 25, 33.8%). Treatments within the cohort include: endocrine therapy (n = 39, 52.7%), chemotherapy (n = 18, 24.3%), observation (n = 9, 12.1%), single agent HER2 inhibitor targeted therapy (n = 4, 5.4%), immunotherapy (n = 2, 2.7%), single agent CDK4/6 inhibitor (n = 1, 1.4%), and radiation (n = 1, 1.4%). Of the 74 patients, 28 had PHQ-9 scores ≥15 at enrollment. On average, ending PHQ-9 scores decreased 39% from the initial score (average beginning score of 19.3 and ending score of 11.3 [n = 19]). 50 patients had GAD-7 ≥10 at enrollment. On average, ending GAD-7 scores decreased 36% from the initial score (average beginning score of 15.4 and ending score of 9.9 [n = 32]). On a 5-point scale, the average patient satisfaction score was 4.3 [range: 4.1-4.5] and the average medical oncology satisfaction score was 4.6 [range: 4.5-4.7]. Financial viability is promising based on projections that 93.4% of psychiatry costs (10% salary + benefits) are covered by reimbursements for care and 2 existing social workers serving as care managers. Conclusions: The collaborative care model is an effective and financially sustainable approach to promptly address depression and anxiety symptoms in BC. Further studies are needed to assess its applicability to patients with other forms of cancers.