5FU dosage in adjuvant chemo

[beach sunrise]

Hi, question for you all. I am on adjuvant folfox6, 8 rounds, and was wondering if there is standard dosage for the 5FU part you take home in the pump for 46 hrs or is it determined by your weight?

[JJH]

Hi, question for you all. I am on adjuvant folfox6, 8 rounds, and was wondering if there is standard dosage for the 5FU part you take home in the pump for 46 hrs or is it determined by your weight?

The standard dosage for the 5-FU part is specified in terms of mg/m2, where m2 is your Body Surface Area in meters squared:

mFOLFOX 6
Oxaliplatin 85 mg/m2
IV, day 1,* leucovorin 400 mg/m2
IV day 1,** 5-FU 400 mg/m2
IV bolus on day 1, then 1200 mg/m2 /d x 2 days (total 2400 mg/m2 over 46–48 hours) continuous infusion. Repeat every 2 weeks to a total of 6 mo perioperative therapy.

In order to calculate your BSA (Body Surface Area) they will need to know both your height and weight:

BSA Calculator
https://globalrph.com/medcalcs/body-surface-area-bsa/

Then in order to know how much 5-FU they need to put in the pump they need to put 2400 in the 'Drug dosage' box before they click on "Calculate".

Please note that if you have significantly gained or lost weight between rounds, your take-home amount of 5-FU in the pump will change.

[beach sunrise]

Thanks for the link, JJH. I must being doing something wrong. I put in H 63", W 97, 2400 for dosage. It came up 2304 for dosage. My 5fu pump bag says 956. It is way off.

[JJH]

There's some sort of inconsistency there, but I'm not sure what. It might be due to a difference in the definition of "dose" vs "dosage"; it might be due to a difference between "continuous ,"and "bolus" dose definitions. I'll look into it and try to figure it out.

Meanwhile, could you be more specific about the 956 pump reading you mentioned? What are the units of measurement? mg? mL? Is this the reading at the beginning when the pump is full? Do you know the name and model of the pump? Does it come with a set of specifications or instructions? How large is the pump reservoir? half a pint? a pint? a quart?

I think that if your objective is to determine if you are getting the correct dose of 5-FU then you would need to see the nursing procedure manual that they use for filling the pump. Do they fill it only with pure 5-FU? Or is it diluted with something else, like water? Or is it combined with a dose of Leucovorin (LV)? Or does it also contain some medications against nausea, etc?

You also need to clarify what the pump display is measuring. Is it milliliters (mL)? Does the digital display have the units indicated to the right or to the bottom of the display? Is it displaying volume of fluid remaining in the reservoir, or is it displaying flow rate (e.g.,mL/minute or mL/hour? or is it something else?

[Rock_Robster]

Thanks for the link, JJH. I must being doing something wrong. I put in H 63", W 97, 2400 for dosage. It came up 2304 for dosage. My 5fu pump bag says 956. It is way off.

When I do this calculation I get 1.99m2 for the BSA, which by coincidence is exactly the same as mine. This should equate to a 5FU dose of 4776 mg (I recall mine was rounded to 4800 mg).

[beach sunrise]

Interesting guys! Pump bag says: fluorouracil 2.5 gram vial (CC), 1.5 ml/hr, COMMENTS: Fluorouracil 3456mg, TOTAL VOLUME 69ml 2.5g Fluorouracil 956 mg Fluorouracil inj 1. Pump says 1.5 mL/hr for 46 hrs. I trust its right but I swear I feel the need to verify "everything". Trust but verify, trust but verify!

[Rock_Robster]

Ok thanks. I can’t claim to understand this fully, but it looks like you might have 3,456 mg of fluorouracil in 69 ml of total liquid (feels about right). This 69 ml total gets delivered at 1.5 ml per hour, which is 46 hours (correct for 5FU protocol, being 48 hours minus your initial ~2 hrs infusion time).

The only part I don’t get is the 956 mg and your total dosing. If we ignore the 956 and just take the 3,456 mg, then it’s only ~70% of the protocol dose (which is entirely possible - oncs often adjust dosages for patients). If for some reason they are added together (3,456 + 956) then this is closer to 90% of the protocol dose.

The 956 mg is also close to your bolus dose but a bit high, and I’m not sure why this would be written on the bottle (and it shouldn’t be deducted from your infusion dose). Unless others have insight on this, it might be one for the pharmacist or oncologist.

Cheers
Rob

[beach sunrise]

Thank you for making it make sense. I was so confused but can see it now. I have no idea what the 956 inj is. They do give me a bolus before they hook the pump up to me.

[JJH]

Thank you for posting the rest of the pump data. Now everything makes sense and everything can be accounted for exactly according to the protocol, even the 956 and the 3,456. So, now you can be assured that you are in fact getting the full recommended dose of pump-based 5-FU.

Keep in mind that before each pump fill-up takes place they will have to put you on the scales and record your weight accurately. If your weight is any different from your weight the time before then they have to re-calculate the pump dose before re-filling the pump. If they don't weigh you again at each round then they are violating the protocol.

[Rock_Robster]

Thank you for posting the rest of the pump data. Now everything makes sense and everything can be accounted for exactly according to the protocol, even the 956 and the 3,456. So, now you can be assured that you are in fact getting the full recommended dose of pump-based 5-FU.

Keep in mind that before each pump fill-up takes place they will have to put you on the scales and record your weight accurately. If your weight is any different from your weight the time before then they have to re-calculate the pump dose before re-filling the pump. If they don't weigh you again at each round then they are violating the protocol.

JJH I’m curious, how do you get to the protocol dose from 3,456 and 956?

Thanks
Rob

[JJH]

... JJH I’m curious, how do you get to the protocol dose from 3,456 and 956?
Thanks
Rob

To respond to your question I will give the steps I took to re-create the data items displayed on the pump bag.

1. Calculate the patient's BSA and required protocol dosage
   By using data from the patient's updated chart, enter the height and weight on the BSA Calculator form.
   
   - Enter 63 in the height box
   - Enter 99 in the weight box
   - Change the height units from centimeters to Inches
   - Change the weight units from kilograms to Pounds
   - Enter 2400 in the "Drug dosage / M2" box (this is the stanardized protocol dosage for a FOLFOX 46-hour pump infusion)
   - Click on the "Calculate Body Surface Area" button and view the results:
   
   - BSA is equal to 1.44 M2
   - Required protocol dosage of 5-FU for this size patient is equal to 3,456 mg
2. Fill the pump reservoir with the required dose
   To fill the pump reservoir with 3,456 mg of 5-FU, two steps are required:
   
   1. Transfer the contents of a 2.5 gram 5-FU vial to the pump reservoir. This is equal to 2,500 mg of 5-FU and consists of 50 milliliters (mL) volume.
   2. Transfer an additional 956 mg of 5-FU to the pump reservoir so that the pump reservoir contains the full 3,456 mg protocol dose. This is done by using a needle and syringe to extract 19.12 millliliters (mL) from a new vial of 5-FU and injecting this amount into the the pump reservoir. (This is because 19.12 mL from the vial contains exactly 935 mg of 5-FU. See the manufactuer's 5-FU data sheet for details.)
   After these two steps have been completed, the pump reservoir will contain 69.12 mL of 5-FU, i.e. 3,436 mg of 5-FU. This is the required protocol dose for a 5'3" 99 lb. patient with a BSA of 1.44 m2 .
   .
3. Set the correct flow rate for a 46-hour pump infusion
   The flow rate on the pump controller must be set so that the contents of the pump reservoir will be exhausted in 46 hours. A flow rate of 1.5 mL per hour will do this. With the flow rate set at 1.5 mL/hour the 69.12 mL of 5-FU will be exhausted in 46.08 hours, which is close enough for current purposes..

[Rock_Robster]

... JJH I’m curious, how do you get to the protocol dose from 3,456 and 956?
Thanks
Rob

To respond to your question I will give the steps I took to re-create the data items displayed on the pump bag.

1. Calculate the patient's BSA and required protocol dosage
   By using data from the patient's updated chart, enter the height and weight on the BSA Calculator form.
   
   - Enter 63 in the height box
   - Enter 99 in the weight box
   - Change the height units from centimeters to Inches
   - Change the weight units from kilograms to Pounds
   - Enter 2400 in the "Drug dosage / M2" box (this is the stanardized protocol dosage for a FOLFOX 46-hour pump infusion)
   - Click on the "Calculate Body Surface Area" button and view the results:
   
   - BSA is equal to 1.44 M2
   - Required protocol dosage of 5-FU for this size patient is equal to 3,456 mg
2. Fill the pump reservoir with the required dose
   To fill the pump reservoir with 3,456 mg of 5-FU, two steps are required:
   
   1. Transfer the contents of a 2.5 gram 5-FU vial to the pump reservoir. This is equal to 2,500 mg of 5-FU and consists of 50 milliliters (mL) volume.
   2. Transfer an additional 956 mg of 5-FU to the pump reservoir so that the pump reservoir contains the full 3,456 mg protocol dose. This is done by using a needle and syringe to extract 19.12 millliliters (mL) from a new vial of 5-FU and injecting this amount into the the pump reservoir. (This is because 19.12 mL from the vial contains exactly 935 mg of 5-FU. See the manufactuer's 5-FU data sheet for details.)
   After these two steps have been completed, the pump reservoir will contain 69.12 mL of 5-FU, i.e. 3,436 mg of 5-FU. This is the required protocol dose for a 5'3" 99 lb. patient with a BSA of 1.44 m2 .
   .
3. Set the correct flow rate for a 46-hour pump infusion
   The flow rate on the pump controller must be set so that the contents of the pump reservoir will be exhausted in 46 hours. A flow rate of 1.5 mL per hour will do this. With the flow rate set at 1.5 mL/hour the 69.12 mL of 5-FU will be exhausted in 46.08 hours, which is close enough for current purposes..

Thanks JJH! I see my issue - I thought 99 was kg, not lbs.

Thanks
Rob

[beach sunrise]

Do you guys know how long the oxa and 5FU keep working to kill cancer after disconnect? I can't find a definite answer on the net. I have found a round about answer of hours is all.

[Rock_Robster]

Do you guys know how long the oxa and 5FU keep working to kill cancer after disconnect? I can't find a definite answer on the net. I have found a round about answer of hours is all.

I think it depends a bit on your definition of “kill cancer” here. Both drugs clear the body quite fast (half-lives of around 15-30 mins), meaning most is gone within a few hours, by about 48 hours it is almost certainly all out of your system. However they work by damaging the cancer cells’ DNA and preventing replication of the cells, meaning the effect on the cells could take as many as several weeks to fully play out. My oncologist’s opinion was that the effects of the drug combo on cancer cell growth probably persist for up to 4-6 weeks.

Cheers
Rob

[beach sunrise]

Yes, clear the body I guess is what I mean. Thank you so much!