## Different types of cancer are classified according to the origin of the cells

There are several types of cancer classification. One of the most common is the classification according to the original tissue type from which the tumour cells originate. According to this classification, a distinction is made between carcinomas which are from epithelial cells (e.g., lung, breast, prostate, pancreas, colon), sarcomas from connective tissue (e.g., bones, cartilage, fat, nerves), germ cell tumours (from pluripotent cells e.g., testis, ovary), blastomas (immature precursor cells of the embryo), lymphomas and leukaemia’s (blood lymph cells - e.g., spleen, thymus, lymph nodes).

However, a tumour cannot be thought of as a mass of identical cells. Rather, it is a very heterogeneous tissue in terms of the presence of different cell types, but also changes at the level of individual cells. The changes in the cells are usually caused by mutations in the DNA, which accumulate during tumour development. Tumours differ not only in their location in the body, the architecture of the tumour, the response of tumour cells to treatment, the effect of the tumour on surrounding tissue, and the ability to metastasize but also in the response of the immune system and the genetic nature of cancer. These are all aspects that are different for each patient. For this reason, the likelihood of finding a single drug in the future that will cure all cancer patients is very low.