Colon Cancer Support Group
Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. Many colorectal cancers are thought to arise from mushroom-like growths that are usually benign, but some may develop into cancer over time. The majority of the time, the diagnosis of localized colon cancer is through colonoscopy.
You might want to research Pseudomyxoma Peritonei (PMP), it's similar to colon cancer but starts in the appendix, if the appendix has burst at the time of surgery, then it can seed into the abdominal cavity (speaking from experience here!).
To my knowledge colon cancer doesn't generally spread to the abdominal cavity, but appendix does, also was there any lymph node involvement?
There is a treatment for this called cytoreductive surgery + HIPEC (Heated Inter PEritoneal Chemotherapy) commonly known as MOAS (mother of all surgeries). If you need help researching let me know and I'll point in the direction of some resources.