  The problem of the onset and growth of solid tumour in homogeneous tissue is
regarded using an approach based on local interaction between the tumoral and
the sane tissue cells. The characteristic sizes and growth rates of spherical
tumours, the points of the beginning and the end of spherical growth, and the
further development of complex structures (elongated outgrowths, dendritic
structures, and metastases) are derived from the assumption that the
reproduction rate of a population of cancer cells is a non-monotone function of
their local concentration. The predicted statistical distribution of the
characteristic tumour sizes, when compared to the clinical data, will make a
basis for checking the validity of the theory.
