The purpose of this research is to evaluate the impact of a microarray PGx test on prescribing/dosing of drugs and cancer treatments in patients with cancer who are currently eligible for single-gene DPYD testing.

This is a prospective, non-randomized, Phase 2 study. The target population is adults ≥18 years of age who have received or will be receiving standard of care single-gene DPYD (dihydropyrimidine dehydrogenase) PGx testing to help guide dosing for their cancer treatment. Pharmacogenes that will be reported back to participants and providers from the microarray test are expected to take approximately one week and will be evaluated by the PGx team and uploaded to the participant's electronic medical record (EMR). Only clinically actionable results per CPIC and FDA guidelines will be included in the participant report. Participants will be followed on study for approximately 6 months to collect data on the number of drug prescriptions with known drug-gene interactions and potentially actionable results, BPAs fired, and actions taken due to BPAs.

Inclusion Criteria:

• Written informed consent and HIPAA authorization for release of personal health information.
• Age ≥ 18 years at the time of consent.
• Eligible for standard of care single-gene DPYD testing (i.e., receiving or expected to receive a fluoropyrimidine-based chemotherapy regimen). The potential participant meets inclusion criteria if the standard of care single-gene DPYD test is planned or previously ordered. If previously ordered, consent must occur no later than 60 days from the date the DPYD results were available.
• Willing to provide additional buccal swabs if residual DNA from previous DPYD testing is inadequate for microarray testing.

Exclusion Criteria:

• History of prior allogeneic hematopoietic cell transplantation or liver transplantation