Told primary is colon cancer, then liver biopsy just came back saying primary is pancreas

Ellemay

Hello, We were told in June mom has stage 4B colorectal cancer metastasized to liver, lungs and peritoneum. Doctor called last night leaving a message that liver biopsy came back and shows primary is pancreas with certain percentages of other GI malignancies. We hope to catch the doctor’s call again today to learn more, but this seems strange. I assume for sure it is in her colon since CT and PET seemed to show that plus she seemed to have had some blockage which is better now from chemo. Why wouldn’t pancreas show on CT or PET? Isn’t it rare to go from pancreas to colon? Can biopsy reports be incorrect? It came from Caris Life. The doctor said treatment is mostly the same. Is pancreatic cancer harder to treat than colon? Does it matter if both are stage 4? Is being in the peritoneum the worst part? She is 81. Thank you!