Hyperhydration of Cancers: A Characteristic Biophysical Trait Strongly Increasing O₂, CO₂, Glucose and Lactate...

Cancers are complex, heterogeneous, dynamic and aggressive diseases exhibiting a series of characteristic biophysical traits which complement the original biological hallmarks of cancers favouring progressive growth, metastasis, and contributing to immune evasion and treatment resistance. One of the prevalent differences between most solid tumors and their corresponding, healthy tissues is a significantly higher water content (hyperhydration) in cancers. As a consequence, cancers have distinctly higher (Fick's) diffusion coefficients D [cm² s^-1] for the respiratory gases O₂ and CO₂, the key substrate glucose, and for the oncometabolite lactate. In addition, cancers have (a) clearly increased specific heat capacities c_p [J g^-1 K^-1], thus representing high-capacity-tissues upon therapeutic heating induced by electromagnetic irradiation, and (b) higher thermal conductivities k [W m^-1 K^-1], i.e., increased abilities to conduct heat. Therefore, in diffusion analyses (e.g., when describing critical O₂ and glucose supplies or CO₂ removal, and the development of hypoxic subvolumes) and for modeling temperature distributions in hyperthermia treatment planning, these specific cancer-related data must be considered in order to reliably reflect oncologic thermo-radiotherapy settings.