How would you approach an adolescent patient with stage IIIC serous borderline tumor, s/p fertility sparing surgical staging with unilateral salpingo-oophorectromy, who presents with an enlarging contralateral ovarian mass and additional pelvic disease on imaging?

I would attempt cystectomy and debulking of pelvic disease. If ovarian salvage is not possible, then I would prioritize saving the uterus.

If final pathology continued to show borderline tumor, then I would observe. If low-grade serous or high grade serous on final pathology, then I would treat with...