Investigating patient vulnerability during fluoropyrimidine-based chemotherapies in a cardio-oncology setting: a retrospective observational study

Introduction Fluoropyrimidine (FP)-based chemotherapy may be associated with cardiovascular (CV) toxicity. Unlike many other oncotherapies, there is no scoring system available for estimating the risks of CV toxicity associated with FPs. Objective We aimed to assess the CV burden of patients, the incidence of cardiological and oncological interventions, and the characteristics of highly vulnerable patients through a retrospective analysis of cardio-oncology consultations requested due to FP-based treatment. Methods By reviewing 1,293 cases seen at the Cardio-Oncology Outpatient Clinic between 2018 and 2024, we identified 220 patients with previous (n=51), planned (n=107), or ongoing (n=62) FP treatment. Previous FP exposure and FP treatments not initiated due to contraindication/patient refusal (n=31) were excluded from our analysis. For the remaining 138 cases, we examined demographic and clinical data, pharmacotherapy, results of the cardio-oncology consultation and oncological decision-making, as well as survival. We analyzed the effects of cardiological or oncological interventions on the survival of patients treated for palliative (n=59) and curative (n=77) purposes. In our research, cardiological or oncological interventions represented the necessity to deviate from default treatment or follow-up schemes. We examined patients receiving 5-fluorouracil (5FU, n=93) or capecitabine (CAP, n=44) treatment protocols separately. Results Cardiological interventions included the need for drug optimization (n=86), additional diagnostic work-up (n=22), close monitoring (n=16), or a combination of these. Oncological interventions included dose reduction (n=9), interrupted (n=2) or discontinued oncotherapy (n=4), or a change in the oncotherapeutic scheme (n=10) in a mutually exclusive fashion. In both the curative (p=0.068) and palliative (p=0.045) groups, the worst survival was shown by those who required both cardiological and oncological interventions at the same time. Approximately 24% of patients receiving 5FU who required cardiological intervention also required oncological intervention, and the 1-year survival of these patients was significantly lower than that of patients who did not require oncological intervention (68 vs. 83%, p=0.04). Conclusion Based on our research, patients receiving FP treatment who require both cardiological and oncological interventions can be considered particularly vulnerable. These patients require special attention during treatment and follow-up due to their expected poor clinical prognosis.