Metastasized to abdominal cavity

My mom had breast cancer 19 years ago at the age of 43. She had a 2 mm tumor and decided to have her breast with the cancer in it removed along with chemo and Tamoxifen for 5 years. She was cancer free until 2 years ago it came back below her collar bone. She had radiation and was put on a medication and they again said she was cancer free but kept her on the drug. She started having severe abdominal pain and was in and out of the hospital 3 different times while they said they couldn't find anything. She decided to go to the surgeon that too kind off her breast. She said it was probably scar and planned to go in and remove it the next day. It ended up being a tumor wrapped around the outside of her small intestine. They also said her abdominal cavity was full of mets. The removed 4 inches of her small intestine. Path came back it's tthe same cancer as the others. She will be on Ibrance and will take shots of another drug every two weeks for the rest of her life. She still has severe abdominal pain when she tries to eat. Has anyone else ever had their cancer spread to their abdominal cavity? In other words it's not in any organ, but on the outside of them