Unilateral ovarian tumor has spread to peritoneum but not to uterus. What is the FIGO staging of ovarian neoplasm in this case?

In this case the tumor has spread to peritoneum not uterus which is usually seen in stage IC of ovarian neoplasm. In stage IC: tumor is either stage IA or IB, but with tumor on the surface of one or both ovaries, or with ruptured capsule, or with ascites containing malignant cells or with positive peritoneal washings. In stage IB: growth is limited to both ovaries, there is no ascites with malignant cells. The capsule is intact and there is no tumor on the external surface. In stage IIA: Tumor involves one or both ovaries with extension to the uterus and/or tubes. In stage IIB: Tumor involves one or both ovaries with extension to other pelvic tiisues. Ref: Williams Gynecology, 2e chapter 35