A 53-year-old woman complains of an aching pain in the lower abdomen, a significant abdominal distention within the last 5 months, weight loss, and weakness. The cervix is clean, the uterus is not enlarged, painless, and immobile. On the both sides, there are dense mildlymobile tumors 10x13 cm in size with an uneven surface. Abdominal percussion detects a fluctuation. Make the right diagnosis: