Tumor doubling question

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Larry Von ND - 24 Jul 2009 02:27 GMT

Saw an old post by Dr Steph relating tumor response to doubling size:

> Is the claim that tumor size reduction is not statistically related to

"Steph" <steph(a)vancouvers.island> wrote
As with most things, the answer is not yes or no.
All cures require a complete response, but not all complete responses
are
cures.

"Cancers grow logarithmically, not mathematically. The first cell
doubles
to become 2, they double to become 4, then 8, and so on.
A cancer which has just grown to detectable size (1cm, or 1 gram, for
argument's sake) has about 10^9 cells in it. That represents about 30
doublings from the original cancer cell.
By the time the cancer has grown to a size of 1.7 kilograms (and is
likely
a threat to life) it only requires 4 more doublings, for a total of
34
doublings. "

Am I missing something here, but for 1 gram tumor to reach 1700 grams
or 1.7 kilos in size, that would be approx 10 more doublings not 4
more , right?

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CSM - 24 Jul 2009 16:53 GMT

> Saw an old post by Dr Steph relating tumor response to doubling size:
>
[quoted text clipped - 21 lines]
> or 1.7 kilos in size, that would be approx 10 more doublings not 4
> more , right?

It's closer to 11 than 10, but yes, you seem to have it right. Four
doublings makes for a multiplier of 16 (so a 16 gram tumor), not
1700. If you're missing something, then so am I, and I've had my
coffee this morning.

FTR, this is *not* "logarithmic growth". Increasing periodically by a
set factor (in this case 2) is known as "exponential", or "geometric"
growth---the mathematical opposite of logarithmic growth. Any of
these growths is mathematical. This is not a flame, but rather a
clarification to reduce confusion.

---
CSM

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