Personalizing Chemotherapy Dosing for GI Cancers

Chemotherapy is a common treatment for many advanced gastrointestinal (GI) cancers. But standard dosing methods leave some patients receiving a lower dose of medication than what they may actually need.

“The current approach to chemotherapy dosing—calculated using a patient’s height and weight—does not account for individual differences between people that can affect how chemotherapy is metabolized in the body,” explains Gabriel A. Brooks, MD, MPH, a medical oncologist in Dartmouth Cancer Center’s (DCC) Gastrointestinal Oncology Program. “As a result, up to 50% of patients may be receiving a dose that is too low, based on measured drug levels in the blood.”

Rethinking how chemotherapy is dosed

To address this issue, Brooks is leading a clinical trial at DCC that is testing a more personalized approach to chemotherapy dosing. The study focuses on a widely prescribed chemotherapy backbone called FOLFOX (5-fluorouracil and oxaliplatin).

“This trial is for patients who will receive the FOLFOX chemotherapy regimen, which includes the drug 5-fluorouracil (5-FU), as the primary treatment for advanced cancers of the esophagus, stomach, small intestine, colon, and rectum,” said Brooks.

Patients begin with a standard dose of 5-FU. For those who tolerate treatment well, without developing unnecessary side effects, the dose is carefully increased.

“The ultimate goal is to establish a new approach to finding an individualized chemotherapy dose for 5-FU that reduces the risk of underdosing and helps ensure each patient receives the dose that is right for them,” said Brooks.

A DCC-led effort

Currently, this research is exclusive to DCC. It is available to patients at the Lebanon, NH, and St. Johnsbury, VT locations. Enrollment is expected to be completed within six months, and study results are anticipated in 2027.

Clinical trials such as the FOX regimen trial reflect DCC’s commitment to precision medicine—adapting treatment to the individual, not just the diagnosis.

“We hope that this approach can lead to better treatment outcomes and improved survival for patients with GI cancers,” said Brooks.

Patients interested in learning more about this clinical trial are encouraged to speak with their oncology care team.