Definition

In medicine, a measure of the amount of DNA or number of chromosomes in cancer cells compared to that in normal cells. Most human cells, except for egg and sperm cells, normally contain 46 chromosomes (23 pairs) in each cell. Cancer cells that have a DNA index of 1 have about the same amount of DNA or number of chromosomes as normal cells. If the DNA index is more than 1, the cancer cells have a higher-than-normal amount of DNA or extra chromosomes. The DNA index may be used to help plan treatment and estimate prognosis for some types of cancer, such as leukemia and neuroblastoma. Also called DNA ploidy.