Most of us love cocktails. . .Manhattan, gin and tonic etc. We know, depending on what we use and how they are mixed, they may taste different.
Well, for the treatment of colon cancer patients we have different cocktails to choose from such as FOLFOX and FOLFIRI. Both are combinations of 5-FU and leucovorin and either irinotecan or oxaliplatin. Both regimens have similar efficacy and similar extent of side effects, with oxaliplatin having more neurotoxicity and irinotecan more diarrhea.
However, depending how you mix and deliver the three drugs you may have significant differences in toxicity. It is amazing what differences exist among oncologists in how they mix up their chemotherapeutic cocktails. Not only the doses but also the timing of administration can differ dramatically, which can result in differences in toxicities for patients.
I have seen many patients with severe diarrhea and nausea and low blood counts using FOLFOX being labeled allergic to 5-FU. Taking the 5-FU bolus infusion away (when they inject 5-FU quickly into your bloodstream), can reduce the side effects dramatically without jeopardizing the efficacy. Similarly adjusting the dose of leucovorin to 20mg/m2 and not 200mg/m2 makes no difference in efficacy but can reduce diarrhea.
When you give 5-FU as a bolus (quick infusion) we know you can develop nausea, vomiting, diarrhea and low white blood cells. When you give 5-FU over time with a slow infusion over 46 hours you don’t see the same amount of these side effects. More likely, you will see dry skin and mouth sores. It is very well established why this is the case based on how 5-FU interferes with the normal cells DNA and RNA.
If you develop significant side effects please discuss modifying the schedule and dose of 5-FU and leucovorin with your oncologist.
Last week, I saw a woman who was receiving bolus 5-FU and leucovorin weekly with a weekly infusion of irinotecan for colon cancer, which is an outdated regimen and should not be given. We have learned a lot over the years to optimize administering drugs.