Background: Inpatient chemotherapy is not routinely recommended for patients with solid tumors as administration is associated with increased length of stay (LOS), higher healthcare costs, and higher morbidity; and chemotherapy administration within 14 days of death is considered poor quality care. However, inpatient chemotherapy may sometimes be indicated for toxicity monitoring or due to barriers that limit prompt delivery of medications with clinically meaningful benefit. To ensure judicious use of inpatient chemotherapy we are undertaking iterative Plan, Do, Study, Act (PDSA) cycles involving education and policy initiatives on a solid tumor oncology service at an urban, academic medical center. Methods: PDSA cycles followed standard methodology. The initial goal was to reduce inappropriate inpatient chemotherapy use, which was expected to correspond with a 25% overall reduction. The initial intervention consisted of two main components: 1) division-wide education about the indications for inpatient chemotherapy, and 2) formation of a committee to review all chemotherapy requests for adult inpatients with solid tumors. The committee consists of clinicians within division leadership, including the division chief and representatives from operations, quality and safety, and ethics. Requests are sent from inpatient teams to the committee, who review each case for factors supporting inpatient treatment such as patient stability/performance status, clinically meaningful benefit, and practical barriers to outpatient administration. To evaluate the impact of the intervention, data were extracted from the electronic medical record for all patients admitted to the service for the 8.5 months before (12/1/22-8/15/23) and after (8/16/23-4/30/24) the initiation of the first PDSA cycle. Results: At baseline, prior to PDSA cycle 1, there were 930 admissions (n=606 patients), and 111 (11.9%, n=82 patients) received inpatient chemotherapy. During PDSA cycle 1 there were 889 admissions (n=557 patients), and 57 (6.4%, n=35 patients) received inpatient chemotherapy (p<0.001). There was no significant change in the proportion of patients receiving chemotherapy within 14 days or 30 days of death pre-PDSA cycle and post, 7.5% vs. 6.6% within 14 days of death (p>0.9), and 13.1% vs. 11.5% within 30 days of death (p>0.9). Overall, mean LOS for all admissions decreased from 11.1 days to 8.8 days (p<0.001). Conclusions: Preliminary results of this quality improvement initiative using iterative PDSA cycles to optimize inpatient chemotherapy use suggest a benefit. After the first PDSA cycle, there was a 46.3% decrease in the proportion of admissions receiving inpatient chemotherapy, and an overall decrease in LOS. Future PDSA cycles are aimed at limiting end-of-life chemotherapy and streamlining the transition from inpatient to outpatient chemotherapy to reduce delays and improve the patient experience.