Oophorectomy in the prevention of ovarian cancer.

The question of whether to remove macroscopically normal ovaries at the time of hysterectomy for non-malignant conditions in women aged 40-50 years or older is still controversial. Estimation of the benefits and potential risks of prophylactic bilateral oophorectomy is difficult. The spokesmen for bilateral oophorectomy claim that this operation prevents subsequent development of ovarian cancer and prevents operation for non-malignant conditions caused by symptoms from the 'residual ovarian syndrome'. The opponents of bilateral oophorectomy claim that healthy organs should be left in situ and that bilateral oophorectomy may cause hormonal deficiency also in postmenopausal women. Ultimately the decision must be taken by the patient, but this decision should be based on as reliable data as possible. Our aim is to try to quantify some of the aspects of bilateral oophorectomy. The life-time risk of developing ovarian cancer in Denmark is about 2% (1). The mortality from ovarian cancer has remained unchanged in the western world for decades; nearly 500 women die annually from this cancer in Denmark. The corresponding figures from Canada, the United States and Norway are 1200, 12,000 and 300 (2). This high mortality is mainly due to the fact that more than 50'% of the patients have a disseminated disease at the time of diagnosis. The late diagnosis is due to the few and vague symptoms and the lack of efficient screening methods for this disease. Furthermore treatment for ovarian cancer has not improved significantly. Attempts to decrease the incidence of and mortality from ovarian cancer have focused on causal research, early detectionlimproved diagnostic methods, better treatment and prophylactic surgery by performing bilateral oophorectomy. In some cases it may be relevant to perform elective bilateral oophorectomy, if the woman has been exposed to etiological factors of importance for the development of ovarian cancer. Women with a family history of ovarian cancer are at increased risk of developing ovarian cancer. In the familiar ovarian cancer syndrome, available data suggest an autosomal dominant inheritance. Women in these families may have a 50%) life-time risk of developing ovarian cancer ( 3 ) , and bilateral oophorectomy may be considered as soon as these women have finished their reproductive career. In families with a single case of ovarian cancer, firstand second degree relatives have been reported to have a relative risk of developing ovarian cancer between three and 18 (3-5). The incidence of ovarian cancer is also increased in relatives of patients with cancer of the breast, colon and endometrium. In a woman with a first-degree relative with endometrial cancer, the risk of developing ovarian cancer is about 3.5'%1 ( 5 ) . I t is known that prolonged anovulation caused by the use of contraceptive pills or by pregnancies has a protective effect on ovarian cancer and conversely that the risk is increased in nulliparous and infertile women, as well as in women with a late menopause (6-8). All the above mentioned women, known to be at an increased risk of developing ovarian cancer, could be a primary target group for ovarian cancer screening, if a reliable and sensitive test is developed. They are also those in whom bilateral