Peritoneal Cavity Cancer

The goal of this clinical trial is to learn if paricalcitol or pirfenidone can help make tumors removable by surgery in adults with peritoneal cancer who are currently unable to have their tumor removed. The study aims to answer are whether paricalcitol or pirfenidone improve tumor response and tissue healing after 12 weeks of treatment, and which of these two drugs is more effective at helping participants become eligible for surgery. Researchers will compare paricalcitol to pirfenidone to see which drug works better and has a manageable safety profile. Participants will take either paricalcitol or pirfenidone by mouth every day for 12 weeks while continuing their standard chemotherapy, visit the clinic regularly for checkups and lab tests, keep a daily diary to track their study medication, and undergo a surgical re-evaluation after treatment to see if their tumor can be removed.