Individualized Dose Escalation of 5-FU for Gastrointestinal Cancer

Inclusion Criteria:

Age ≥ 18 years
Diagnosis of metastatic or locally advanced/inoperable colorectal cancer or non-colorectal gastrointestinal cancer (including cancers of the stomach, esophagus, appendix, small bowel, and ampulla)
Clinically appropriate staging imaging of the chest, abdomen, and pelvis performed within 30 days prior to registration
ECOG Performance Status: 0-1

Exclusion Criteria:

Any prior receipt of oxaliplatin or fluoropyrimidine chemotherapy (other than radiation-sensitizing fluoropyrimidine chemotherapy)
Prior receipt of systemic chemotherapy in the 6 months prior to Day 1 of Cycle 1 of FOX (other than radiation-sensitizing chemotherapy)
Known mismatch repair deficiency or microsatellite instability-high disease
Known dihydropyrimidine dehydrogenase (DPD) deficiency, as identified by clinically indicated screening
Any confirmed second malignancy that is likely to require systemic therapy during the course of the six-month study period, in the opinion of the enrolling investigator

Any of the following baseline laboratory abnormalities:

Absolute neutrophil count (ANC) < 2,500/mm3
Platelet count < 100,000/mm3
Hemoglobin < 9 g/dL
Creatinine > 1.5 x ULN
Total bilirubin > 1.5 x ULN
AST/ALT > 5 x ULN
Patients who are unable to provide informed consent
Patients who are pregnant or breastfeeding
Patients who are incarcerated, homeless, or have active substance use disorders