Sarcoma information

Hi everyone,

My dad was diagnosed with sarcoma in his intestine. omentum and perietal peritoneum. He did a surgery and the surgeon took the three tumours in these three different areas out. However now he has done a CT Scan and thr lab test says that scattered 'peritoneal deposits are noted' on his left and right pelvic cavity. Does anyone know what it is? How dangerous is it? Or anyone been in a similar situation?

Thank you