On a cellular level, what causes cancer?

Answer 1

mutations

Answer 2

generally, cellular mutation caused by stem cells that mutate for some reason - there isn't really a clear-cut reason why - and then multiply rapidly and infect other cells at an increasing rate.

Answer 3

Cancer is very difficult to explain in a medium like yahoo answers. But I will try to make it clear to you. So you understand how mitosis works, and that cells have a "cell cycle" system built into their DNA, and when this cell cycle says it's time for this cell to divide, it divides. It also tells cells that it's NOT time to divide yet.

Basically, the cell cycle works under the control of cell cycle regulating protein complexes called cyclins and CDKs. When this process of cell cycle control is lost by some kind of mutation, the cell loses control, and replicates uncontrollably.

Now, if it's built into DNA you might ask, how can different cells divide at different rates? Well cells are constantly in communication with each other by cell signaling (ligand/receptor or steroid hormones), and cell-cell adhesions. So there are various signaling pathways that originate outside the cell, come into the cell by some kind of signaling pathway, and tell the cell "this is how and when you are going to divide or not divide", and the cell transcribes the proper genes, and there you have it, control of the cell cycle!

For those who are unfortunate enough to have a mutation in a gene associated with the cell cycle itself, or a pathway that directs cell cycle regulation (a transcription factor like p53 is the best example we have), the cell cycle will not be properly regulated. So, we have named 2 types of genes that are implicated in cancer, "oncogenes" and "tumor suppressor genes". Oncogenes are genes that directly or indirectly tell the cell under normal conditions, "it's time to divide!", and tumor suppressor genes are genes that tell the cell "it's not time to divide". In normal conditions, the body's signaling pathways control both of these, and there is a fine balance. If there is a mutation in an oncogene, or a tumor suppressor gene, the cell loses control of it's cell cycle, and replicates uncontrollably!

You have to realize that MANY MANY pathways converge at the point of cell cycle regulation, way too many to list to you and explain to you, but it is important to recognize that it is a lot. And if something were to happen to just one of these pathways, the cell might lose its cell cycle control. This variety of pathways also explains occurrence of different types of cancers! Different cell types rely on different signaling pathways to regulate their cell cycles.

Answer 4

basically its uncontrollable growth of cells. once a cell has cancer, it will just keep multiplying to form more cancer cells, which in turn will keep on multiplying and plutiplying. this is basically what causes tumors.

Answer 5

I like to think of it as "Mitosis Gone Mad." It's when cells divide at a crazy speed.

Answer 6

when a cell loses the ability to control cell division and cell growth.