[MattSchtick]

What is the area (m2) used in dose calculations?

by MattSchtick on Sat May 10, 2014 10:54 am

As I head towards stem cell mobilization and harvest, which will involve Neupogen and cyclophosphamide, I see the units for the cyclophosphamide dosage are quoted in g/m2 (grams per metre squared) and are usually about 1- 4 g/m2.

I do not understand what the area is that is being measured in metres squared.

I am currently taking weekly cyclophosphamide on my VCD induction as 10 x 50mg pills = 0.5g, so to bring this amount into the range 1-4 g/m2 the area would have to be about 0.5 - 0.12 m2 (an A4 sheet of paper is about 0.06 m2).

What does this area refer to?

Last edited by MattSchtick on Sat May 10, 2014 6:04 pm, edited 1 time in total.

[Ian]

Re: What is the area (m2) used in dose calculations?

by Ian on Sat May 10, 2014 11:27 am

Hi Andy,

The surface area referenced in those units is "body surface area". It means exactly what you would expect from the name. It's the surface area of the patient's body.

There are different formulas that doctors and nurses use to calculate a patient's body surface area. Most, if not all, use the patient's height and weight to do the calculation. The Wikipedia article on the topic has more useful information and example formulas:

http://en.wikipedia.org/wiki/Body_surface_area

One thing to keep in mind when using these formulas is that you have to use the right units. Almost always, you have to use weight measured in kilograms and height measured in centimeters.

Weight in kilograms = (weight in pounds) / 2.2.
Height in centimeters = (height in inches) x 2.54

There are various online body surface calculators out there. Just do an Internet search on "body surface area calculator " and you'll find many of them.

[Multibilly]

Re: What is the area (m2) used in dose calculations?

by Multibilly on Sat May 10, 2014 2:44 pm

There appears to be more folks that are questioning the use of body surface area (BSA) to establish a dose for chemotherapy purposes. But the challenge has been what to use instead of BSA for a yardstick?

Note this novel alternative approach (see the section on Saladax):

http://www.ivdtechnology.com/article/innovation-helping-personalize-medicine

Note that they have been issued patents to use this same technique for Revlimid and Thalidomide.

http://books.google.com/books?id=CB_mA_UFqq4C&pg=PA115&lpg=PA115&dq=saladax+myeloma&source=bl&ots=EvsHPG5S_T&sig=xrCV3drI-NJiHfY6BYFw8h5j92k&hl=en&sa=X&ei=Wm9uU4bxJ8enyASKh4HoBA&ved=0CFAQ6AEwBA

If you take the time to read the above link, it does make one wonder how many often a particular multiple myeloma treatment fails or misses the mark simply because the right dose wasn't utilized for a given person based on the variables they mention?

This would be a nice step in the right direction of more personalized treatment for multiple myeloma patients.

[MattSchtick]

Re: What is the area (m2) used in dose calculations?

by MattSchtick on Sat May 10, 2014 6:18 pm

Thanks Ian and Multibilly, situation clarified, keep up the good work.