Ovarian cancer is the fifth most common cancer in women and the second most common gynaecological cancer, but the most common cause of death from gynaecological malignancy in the Western world. Epithelial ovarian cancer, fallopian tube cancer and peritoneal cancer share similar characteristics and behaviour and are treated in the same way. Ovarian cancer has been named a ‘silent killer’ because of its lack of symptoms during early stages. Around 90% of ovarian cancers arise from the epithelium. Two-thirds of patients present with stage III or IV disease, with increasing abdominal symptoms including ascites. Treatment typically depends on a combination of surgery and chemotherapy. In recent years there has been interest in the role of biological treatments, particularly the angiogenesis inhibitor, bevacizumab. Over the past 40 years there has been a modest increase in the survival from ovarian cancer in the UK, attributable primarily to the use of platinum-based chemotherapy, and around 40% of patients are expected to survive for 5 years or more.
Types of tumour affecting the ovary
The WHO classification of tumours of the ovary defines broad categories of ovarian tumours (WHO classification, 2003):
• surface epithelial–stromal tumours;
• sex cord–stromal tumours;
• germ cell tumours;
• tumours of the rete ovarii;
• miscellaneous tumours;
• lymphomas and haematopoietic tumours;
• secondary tumours.
Surface epithelial–stromal tumours are classified as benign, borderline or malignant. The subtypes are serous, mucinous, endometrioid, malignant mixed müllerian tumour (carcinosarcoma), clear cell, transitional cell, squamous cell, mixed and undifferentiated or unclassified.
Sex cord–stromal tumours are classified as granulosa tumours (including granulosa cell tumours and theca-fibroma tumours), sertoli cell tumours, sex-cord tumours of mixed or unclassified cell types, gynandroblastoma and steroid cell tumours.
Germ cell tumours are classified as primitive germ cell tumours (including dysgerminoma, yolk sac tumour and embryonal carcinoma), biphasic or triphasic teratomas (including immature teratoma and mature teratoma), and monodermal teratoma (composed of a single type of tissue and includes struma ovarii, which is composed of thyroid cells).
Incidence and epidemiology
The annual incidence of ovarian cancer in the UK is 17 per 100,000 women, ranging from 14 per 100,000 in Northern Ireland to 20 per 100,000 in Wales. Approximately 7000 cases are reported per year in the UK.