  We have previously reported that a 'universal' growth law with fixed scaling
exponent p, as proposed by West and collaborators for all living organisms,
appears to be able to describe also the growth of tumors in vivo. Here, we
investigate in more detail the dynamic behaviour of p using data from the
literature. We show that p initially decreases before it again increases up to
or even beyond 3/4. These results support the notion that p can vary over time
and yet its dynamics are independent from the cancer type.
