Personalised Timing of Interval Debulking Surgery in Advanced Ovarian Cancer

This study is testing whether tracking a blood marker called CA125 can help doctors choose the best time for surgery in women with advanced ovarian cancer who are first receiving chemotherapy to shrink their tumors. **You may be eligible if...** - You are 18 or older - You have been diagnosed with stage III or IV ovarian, fallopian tube, or primary peritoneal cancer - Your cancer cannot be surgically removed right away, so you are starting chemotherapy first - You are in generally good health (able to carry out daily activities) - You have an elevated CA125 blood level at the start - You have had imaging scans (CT, PET-CT, or MRI) of your abdomen and pelvis - You are willing to have surgery and follow-up chemotherapy as part of the study **You may NOT be eligible if...** - Your cancer is a non-epithelial type (e.g., germ cell or sex cord tumor) - Your cancer can be fully removed with surgery right away - You are not healthy enough for surgery - You are pregnant - You started chemotherapy at another hospital more than one cycle ago Talk to your doctor to see if this trial is right for you.