Re: WHAT ARE THE CAUSES OF BREAST CANCER.

Hi!  You ask very good questions.  Many scientists who are studying breast 
cancer are asking those same questions.  If we can find out what causes 
breast cancer, and how breast cancer cells get into other parts of the 
body, we should be able to stop cells from becoming a cancer, and from 
spreading.  

Nobody knows for sure exactly what causes breast cancer, but we do have a 
good general idea.  Normally, cells in adults don't divide very much.  They 
are well behaved and pay attention to signals, or instructions, coming from 
other cells.  Cancer cells are kind of like the bad kid in the class.  They 
don't pay attention to the signals coming in from other cells, and divide 
even when they are getting instructions not to divide.  

Why do they do that?  Cancer cells have "mutations", or mistakes, in their 
DNA.  These mistakes in DNA cause messed up, or "mutated" proteins to be 
made by the cell.  The mutated proteins don't do their job correctly, so 
the cells don't get the right instructions from other cells, or don't 
follow the instructions they do get.  

What causes the mutations?  Well, DNA mutations are caused by a lot of 
things, including UV radiation from the sun, certain chemicals which can 
break or alter DNA, or just by chance mistakes.  Every cell has a LOT of 
DNA, and every time it divides, it has to copy all of it.  Imagine copying 
the dictionary with pencil and paper, and not making any mistakes. Even if 
you had someone look over it for you, there would probably still be a 
mistake.  The cell checks the DNA, but it sometimes makes mistakes.  These 
mistakes can lead to messed up proteins, and bad changes in cell behavior 
that can lead to cancer.  Sometimes, cancer can run in families.  That is 
because your DNA came from your mom and dad.  If they already had a 
mutation, they passed it on to you.  This is called "genetic 
predisposition" to cancer.

How does cancer spread?  Somtimes once a lump of cells has grown, one of 
those cells will get another change in the DNA.  That mutation may cause a 
change in how that cell interacts with its neighors.  Instead of holding on 
tight to its neighbors, and staying put, the cell might let go of the 
neighbors, and get into the "lymph" or fluid that surrounds the cells, and 
be washed to another part of the body.  In cancer, that event is called 
"metastasis". 

We don't know why cancer happens, or why it spreads.  I think it's pretty 
much just bad luck. We are just starting to get an idea about how cancer 
works, and hopefully soon we'll be able to make it stop.