This discussion came up in our Compuserve cancer forum, arising from some questions from Barbara, and here's hoping that this layman description will be helpful for you.
|Note: If any medical professional reads this and wishes me to correct or clarify anything I have said here, please let me know. I am not proud. Leastways, not at the expense of truth.|
>>> What causes a cell to metastisis? Is it a breaking off or is it a natural inclination of the cell's parts to leave....<<
Pitifully little is known about this.
One of the factors is cell form. You've probably noticed that path reports discuss cell form -- terms like "anaploid", "diploid", etc. This is where the pathologist communicates to the onc how much (or how little) the tumor cells look like normal cells. For example, with breast cancer, how much does the cell look like a normal breast-tissue cell.
The reason why this matters is that it is believed that the less a cell looks like a normal one, the more likely it is to metastasize. The more specialized a cell is, like a cell that is designed to be breast tissue, the less likely it is to survive elsewhere, trying to do something else. In other words, if you're a very specialized lung cell, you wouldn't be especially happy living in the liver. But if a cell is sort of generic ("poorly differentiated" is one of the terms they use), then it might have the opportunity to adapt to a completely different neighborhood.
To sum it up, it's thought to be a measure of a cancer cell's ability to travel. Because it's believed to be a measure of likelihood to metastasize, it's therefore a weight-y factor in the treatment decision. For example, if the onc is feeling otherwise borderline about whether to do chemo, this might tip the scales to make him choose so.
>>Is it the original cell looking for nutrients? Is it part of what makes a cancer cell, a cancer cell?<<
No, original (normal) cells do not metastasize. That's part of the definition of cancer is that, unlike normal cells, they multiply in an abnormal and uncontrolled manner.
Food: Another factor in metastasis is a food supply. One condition that aids metastasis is that in some people, with some kinds of cancer, the blood vessels also multiply in an abnormal way, providing food for the breeding cancer cells. I don't think a whole lot is known about this process. Sometimes cancer cells grow too fast for their food supply, and the pathologist will see cells that died from hunger. They call this "necrosis" and they believe it gives them yet another measure of the agressiveness of the cancer cells.
>>at what point in a cancer cells development does it decide to metastisize<<
To my knowledge, nobody knows.
>>does all cancer cells metastisis<<
Not all cancers metastasize, thank goodness. DCIS is a good example of one that often doesn't -- often, it just sits around being abnormal, and not bestirring itself to do anything more dramatic.
>> and what is the purpose of metastisis.....Evidently, it is not for the cells survival as metastisising itself eventally destroys the host...So why would a cancer cell metastisis?<<
One would imagine that, like all living things even down to the cellular level, it wishes to survive, and to propagate itself. Cancer does not always kill the host. Or sometimes, it doesn't kill the host for a very long time. But remember that, on a cellular level, we're not dealing with the complex survival drives of a multicellular creature. I.e., it doesn't have a "wish" to survive, like a person. This "wish" is a metaphor for what is probably only a chemical reaction. I don't personally believe that cancer cells have a true "drive" to succeed. To my unprofessional thinking, it's simply an accidental mistake in how cells work, and the mistake continues as long as the biochemistry promotes the continuance of the mistake.
>>I have read that cancer cells are very clever at hiding themselves from the immune system, the so called enemy. Once they are revealed to the immune system the immune system has the ability to kill the cancer cells<<
This is believed to be true, and I myself believe it. My system, for example, was clever enough to spot and trash the chemo toxins, but not clever enough to do the same with the cancer cells, hence my recurrence.
But cancer is a term used for many very different phenomena, which have many different causes. Cancer can be caused by a variety of damaged genes that erroneously give growth messages, or a damaged gene that fails to give growth-suppression messages after growth has occurred, or by a variety of damaged genes that fail to trigger cell-suicide (apoptosis) when a bad cell has been born, or by a damaged gene that cause the gene's life-length clock (telomeres) to stop controlling the cell's lifespan, and many, many other causes. There are many kinds of cancer that the immune system simply isn't adequate to deal with.
We are only in the infancy of any understanding of this, so metastasis remains a dark mystery.
Love & hugs,
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