One important germline PGx gene for cancer related medication is DPYD (gene encoding for the dihydropyrimidine dehydrogenase: DPD) [287] involved in the degradation of fluoropyrimidines, which are the main chemotherapeutic agents used in many types of cancer: 5-fluorouracil, (5-FU), capecitabine, and tegafur. Here, DPYD is linked to cancer.