Tumor growth rates

[tivol at tethys.ph.albany.edu]

Dear Ian,
	With the exception that y=1 at t=0 (y=0 makes no sense for finite t),
the equation you give seems reasonable.  Furthermore, if y is the number of
cells in the tumor, even y=1 @ t=0 is reasonable.  N.b. the proper measure-
ment for tumor size should be volume (or # of cells).  Assuming that all the
tumor cells are the same size and that the growth *is* exponential, every-
thing should work.  I would be concerned if this equation were extrapolated
too far, since limits to tumor growth (e.g. vascularization, immune response
etc.) would change the growth rate.  I am not an expert on tumors, so take my
post strictly for the mathematics, not for the biology.
				Yours,
				Bill Tivol