from a physics point of view the only additional strain on the back is the weight of the strap. The tumor is already pulling on her back regardless of how restrained it is. If she is otherwise health and the lump/tumor is causing mobility issue why not have it removed surgically?My 14 yr old is in pretty good shape... still eating well, loves to go for short walks, has several feral cat best friends in our yard. She gets acupuncture once a week and it really keeps her going. She has a couple of small lumps on her shoulders but I'm concerned with the large fatty lump that she has developed on her lower belly. While it doesn't seem to bother her I wonder if I should try to rig some kind of devise that would relieve some of the droop.... a cummerbund of sorts that would lift the lump a little. I just don't know if it would add strain on her back. Any thoughts?