Tuor heterogeneity described as having intertumoral heterogeneity or intratumoral heterogeneity.
Intertumoral heterogeneity can be defined as variations among tumors of different tissues and cell types, and variations between tumors of the same tissue type from different patients, and variations between different tumors within the same individual.
Intratumoral heterogeneity refers to variations of cancer as observed within a single tumor.
Tumor cell populations can differ by: cell surface markers, genetic or epigenetic changes, genetic stability, resistance or susceptibility to therapy, and varying growth rates.