ABSTRACT
Clonality implies that cancer, which may comprise thousands of millions of cells, originates from a single cell. The ability of a single cell to give rise to large numbers of cells is not limited to cancer. Normal tissues include a permanent set of stem cells. Molecular technology provides less awkward ways of showing clonality. Gene rearrangement is the basis of the uniqueness of cells of the immune system. Polyclonality is different from subclonal generation. Within a neoplasm, and perhaps especially during early neoplastic evolution, new mutations are arising constantly. Metastatic cancer cells have requirements about where they will and will not grow. The liver is a popular site for most carcinomas and lymphomas but not for sarcomas. Sarcomas rarely metastasise to any sites other than the lungs. Reliance has to be placed on other prognostic factors and these will largely be based on the pathological examination of the specimen.
