I so understand your secondaries anxiety. I too had mastectomies 2006 and 2007 to different types of primary tumours.
Ref your spinal fracture, I don't know how old you are and whether post menopause??
Whether your bones are lacking calcium due to it (menopause). Whether you may have oesteoporosis, so your bones aren't as resistant to trauma/a fall, so fracture that much more easily?? Was it giving you pain, as it was scanned??
Why don't you get back in touch with them, to have a deeper discussion about the fracture, why it may have happened, and air your worries/concerns about possible secondaries. Ask if you can have further tests for bone density/calcium levels??
Hope you get some further insight into it, to give you a bit of peace of mind. xxxx