Impact of a pharmacist-led pharmacogenomic service on test capture rates in oncology: A retrospective pre-post cohort study, 2024-2026

Background Pharmacogenomic (PGx) testing can support clinical decision-making to reduce toxicity associated with commonly used oncology therapies. However, PGx testing remains underutilized in oncology practice due to lack of personnel to coordinate testing. We evaluated whether the implementation of a pharmacist-led PGx service increased PGx testing among oncology patients. Methods We used a retrospective cohort study to compare outcomes from the pre-and post-intervention periods following implementation of a pharmacist-led PGx service within our Duluth oncology clinic, Minnesota-USA. EHR/laboratory data were extracted on adult cancer patients with planned/receiving 5-fluorouracil, capecitabine, or irinotecan between September 1, 2024, and March 31, 2026. The primary outcome was PGx capture, defined as the rate of patients who received PGx testing prior to chemotherapy initiation. Secondary outcomes included tests with actionable results and the proportion leading to therapy modification. Descriptive statistics, Chi-square test, Mann-Whitney U test, and adjusted (age and sex as covariates) logistic regression were used. All analyses were performed using SPSS (IBM 29.0) and RStudio (2025.09.1 + 401) with a statistical significance at ≤0.05. Results A total of 184 (N) eligible patients were included, with 107 in the pre-implementation group and 77 in the post-implementation group. PGx test capture rates increased from 25.2% in the pre-implementation group to 53.2% post-implementation (P < 0.001). In adjusted analysis, the post-implementation group remained significantly associated with higher PGx testing (OR = 3.40, 95% CI: (1.82,6.36)) Conclusion Implementation of a pharmacist-led PGx workflow substantially increased testing. Integration of pharmacists into oncology PGx services may improve the identification of clinically relevant variants and support medication optimization.