From 'oophorectomy' article: In the case of humans, oophorectomies are most often performed due to diseases such as ovarian cysts or cancer; prophylactically to reduce the chances of developing ovarian cancer or breast cancer; or in conjunction with removal of the uterus.
Ovarian cysts themselves are not considered diseases and therefore should not be described as such. Doing so propels an inaccurate view that all ovarian cysts are cancerous when typically they are benign/non cancerous and disappear on their own in a matter of weeks without treatment. The above statement should be rephrased to correct the inaccuracy. http://www.emedicinehealth.com/ovarian_cysts/article_em.htm
In the case of humans, oophorectomies are most often performed when typically benign ovarian cysts