Urogenital ImagingCarcinoma, ovarian
the second most common gynaecological malignancy; endometrial cancer is the commonest. However, because of its high mortality, ovarian cancer is the commonest cause of death from gynaecological malignancy. The lifetime risk of ovarian cancer in women is 1.5%. Approximately 60% of women who develop ovarian cancer will die because of it. The relatively high mortality of ovarian cancer is largely due to the fact that most cases present late, when the disease has already reached an advanced stage. The peak age of incidence of ovarian cancer is 70 years, but 50% of cases occur in women under 65 years.
Despite numerous epidemiological investigations, a clear-cut cause of ovarian cancer has not been defined. Positive family history, late menopause, nulliparity or late childbearing are risk factors. Mutations of the BRCAI tumour suppressor gene are responsible for a large proportion of hereditary ovarian cancers, and also for the association between ovarian and breast cancer. Ovarian cancer is also commoner in industrialized Western countries and Caucasians. The use of oral contraceptives, breast-feeding and pregnancy decrease the risk. The commonest types of ovarian cancer are serous cystadenocarcinoma (40%), endometrioid (20%), germ cell cancer (20%), mucinous cystadenocarcinoma (10%), and sex-cord stromal tumours (5%).
Ovarian cancer frequently presents with abdominal swelling due to ascites, or with vague lower abdominal pain. At ultrasound, CT or MRI, cystadenocarcinomas appear as predominantly cystic tumours, usually over 4 cm in diameter. Findings suggestive of malignancy are intracystic papillary projections, and large solid components or nodules. Thickened cyst walls or septae of over 3mm are less reliable signs of malignancy.
The staging of ovarian cancer is based on the criteria established by the International Federation of Gynecology and Obstetrics (FIGO).
Stage I refers to disease confined to one or both ovaries.
Stage II refers to disease which has spread to the uterus,
Fallopian tubes, or other pelvic tissues, or which is present on the ovarian surface or in peritoneal fluid or washings.
Stage III refers to disease which is associated with
lymph node metastases, or peritoneal implants outside the
pelvis.
Stage
IV refers to disease with distant spread, such as parenchymal metastases in the liver or spleen, or cytologically proven
malignant pleural effusion.
CT and MRI may demonstrate evidence of malignant spread, such as pelvic organ involvement, pelvic side wall invasion, peritoneal or nodal metastases, ascites and lymphadenopathy (Fig.1). Common sites for peritoneal seeding include the pouch of Douglas, hepatorenal pouch, paracolic gutters, subphrenic space, porta hepatis, fissure for the ligamentum teres, greater omentum (Fig.2) and small bowel mesentery. Lymphatic spread may occur to pelvic, inguinal, iliac and retroperitoneal nodes. Haematogeneous spread is a late occurrence, and parenchymal metastases in the liver or spleen are extremely rare at initial presentation. CT is currently recommended as the imaging modality of choice for staging ovarian cancer. MRI is helpful in patients with renal impairment or a history of iodinated contrast medium sensitivity.
The primary treatment of ovarian cancer is surgical removal of all resectable gross disease, including total abdominal hysterectomy, bilateral salpingo-oopharectomy, and infracolic omentectomy. Lymph node sampling or dissection may be appropriate. Adjuvant postoperative radiotherapy or chemotheraphy may be required for advanced disease.
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