I am not a doctor, but I have survived breast cancer twice. I have never heard of a cancerous tumor "bursting," however, I would strongly suggest your friend get a second opinion immediately. Mammograms are very good at detecting even the smallest tumor, yet they are not perfect and cannot detect all cancers. MRI's are much more definitive. The most important thing your friend can do is ADVOCATE for herself, and insist on further testing. I hope this answer helps, and I wish your friend the very best.