Hello all. I had a question about osteosarcoma and how aggressive it is and what are the signs of metastasis?  I may just be watching every little thing too closely, and part of this is me attempting to deal with this nasty disease that has taken over my girls' body....but, she seemed to have lost a good amount of weight fairly quickly. She is eating and drinking, going to the bathroom #1 and #2, although she is not eating as much as she was. Also, I've noticed today that her breathing seemed to be more labored after she went out and came back in. I know that her body is adjusting to the huge changes related to amputation, and I know it is exhausting for her. She goes in for her first round of chemo on Monday, and I'm scared to death.  Has anyone dealt with this before?