Key to solving cause of many types of cancer?: What constitutes "cell damage"?

[Iamme]

Let's take skin cancer, as one example. The cells get damaged? (is that close enough to say?) due to a severe burn from 20 years ago, let's say. Then comes the cancer. Cell damage? Could you also call that an irritant to the cell?

Then what about an area of your body that constantly is being annoyed by something, and say a callous repeatedly grows there? Why does that form a callous and not a tumor? Shouldn't that too be an irritant to the cells there?

[JJM]

Let's take skin cancer, as one example. The cells get damaged? (is that close enough to say?) due to a severe burn from 20 years ago, let's say. Then comes the cancer. Cell damage? Could you also call that an irritant to the cell?

Then what about an area of your body that constantly is being annoyed by something, and say a callous repeatedly grows there? Why does that form a callous and not a tumor? Shouldn't that too be an irritant to the cells there?Sunlight (UV) damages the cells chemically; altering the DNA such that, when the cells divide, the daughter cells are not normal. Random mutations and chemical activity can also do this.

Physical irritation may damage cells causing them to die because they are torn open or removed. It may also cause them to grow (excessively; but normally), as a response to irritation. I don't know if there are any purely, physical irritants that cause cancer; but, I am willing to learn (asbestos comes to mind).

[krazyKemist]

There is a difference between a "growth", like a cyst, a callus, or a wart, and cancer. Many tumors also, are actually not "cancerous".

It's called cancer when there is :

1- Uncontrolled cell division (no response to signals that terminate mitosis or cause apoptosis, ie, cell suicide)

2- The potential to invade surounding tissues, what is called metastase. A tumor that has this capacity is called malignant, and it is a cancer.

Both have very different aspects macroscopically (their shape and texture on a scan or directly seen during surgery) and under a microscope, which allow to diagnose weither or not they are cancer.

[paximperium]

As already been mentioned, the major difference between skin damaged cells from UV light Vs. damage from irritation and even regular burns, is what happens to the underlying DNA.

Cancer requires certain mutations. If all it does is uncontrolled cell division, it becomes a benign mass(or locally invasive). It requires additional mutations to lead to local spread and invasion and to distant metastasis. For certain cancers, this takes a step wise manner(Cervical Cancer is an example) but for others, the cascade is very rapid and goes from abnormal cells to metastatic very quickly.

[jli]

I know that this thread has almost passed on to oblivion, but to set the record straight a few minor comments should be made. It is a common misconception that the cells of a neoplasm divide uncontrolled. It is more correct to say that a neoplasm is not subjected to normal growth regulation (whatever that is). It will not grow indefinately. By definition a neoplasm is malignant (= cancer) if it has the capability to spread throughout the body, and as a result of that causing death. This definition is not perfect. But it works in most instances.