Home Ovarian cancer Ovacome Christmas Cards 2008 Ovacome Calendar 2009 Resources Real-life stories Newsletters News What you can do About us

What are the different types of ovarian cancer?

This piece sets out the different types of ovarian cancer, their characteristics and treatment differences where they exist. It is meant as a resource for readers who remain confused about this complicated issue. However, confining it to two pages means that there may be oversimplification in places.

Ovarian cancer is classified into different types on the basis of its histological appearance – that is, how it looks to the pathologist through the microscope. The majority of ovarian cancers fall within the category of epithelial ovarian cancer. The remaining 10% consist of rare types.

Epithelial ovarian cancer

The greatest clinical challenge among gynaecological cancers. Approximately 6400 new cases are diagnosed annually and this figure is rising. In the UK the overall five-year survival is around 28%. Optimists like me hope this figure is also rising. Three-quarters present with advanced disease, which has spread outside the pelvis.

Within epithelial ovarian cancer (OvCa) there are six subtypes (% frequency in brackets). Each is derived from a different type of tissue in the lower genital tract (also known as the Mullerian tract). However, within invasive cancers there is not a great deal of difference in prognosis for the first three and the distinction is mainly a pathological one.

Serous
This form accounts for around 70% of cases and is therefore the most common type.

Mucinous
This accounts for a further 10%. These tumours have a slightly worse prognosis than serous tumours.

Endometrioid
These tumours (5%) are more likely to be associated with disease in the uterus (womb) and sometimes an ovary is found to be affected when a woman is diagnosed with endometrial cancer.

Clear cell
These tumours (around 3-4%) have a poorer prognosis and tend to behave more aggressively. Pathologists do not usually grade these tumours since, whether they are Grade I, II or III, this tendency exists and grade is not helpful in predicting prognosis.

Borderline tumours
10-15% of ovarian cancers are borderline tumours, also known as tumours of low malignant potential. They tend to remain confined to the ovary for long periods and usually occur in premenopausal women. Implants outside the ovary can arise but there is currently no evidence that the course of this disease is altered by chemotherapy. However, some novel treatments such as matrix metalloproteinase inhibitors may well have a role: the difficulty is establishing a trial in a group of patients with an uncommon disease, as even somebody specialising in the treatment of ovarian cancer will only see a handful of such patients a year. An invasive group has been described and this type may behave more aggressively and ultimately lead to death; the disease course tends to be long over many years.

Treatment of the different types of epithelial cancers is essentially the same. In those fit to receive it the current gold standard is Taxol and a platinum analogue (cisplatin or carboplatin). This is based on the results of two randomised trials conducted in North America and Europe.

Germ cell tumours

Germ cell tumours of the ovary make up 3% of malignant ovarian tumours, so they are rare, just one-tenth as common as germ cell tumours of the testis. Hence advances in treatment have largely developed through treatment of the testicular tumours which are of the same origin – from the germ cells of the ovary – in other words the cells that ultimately become eggs.

Germ cell tumours themselves are divided according to their main cell type; they range from embryonal carcinoma at the most undifferentiated end of the spectrum (in other words very immature cells) via immature teratoma through to mature teratoma. The most common type is a dysgerminoma, accounting for 30-40%. A detailed discussion is not realistic within this space but if you have a germ cell tumour of the ovary then you should be managed within a specialist unit with particular experience. They tend to occur in young women (the majority between 10 and 30 years) and adolescents and if managed correctly usually have a good prognosis

The rare forms include:

Staging

The stage describes the spread of the cancer at the time of diagnosis and this should be established at the initial operation. Such an operation – carried out by a gynaecological oncologist in an ideal world – is known as a staging laparotomy.

The details of staging, which is complex, may be confusing. The table above outlines the basic stages; within each stage patients are divided into A to C, the latter being the highest risk. In Stage I, A denotes confined to the ovary and C that disease has spread outside the ovary or the capsule has ruptured. In Stage III this relates to the amount of disease left at the end of the operation, C being the greatest.

Grade

This is divided into three categories – I (low), II (intermediate) and III (high) – and is a prognostic factor. In other words, patients with low-grade tumours have a better outlook (and some may coexist with their disease for many years) than those with high grade tumour of the same stage. However, this is only one of a number of prognostic factors and cannot be taken in isolation. For example, a grade III Stage IA tumour will usually have a better outlook than a Stage IIIC grade I tumour.

Treatment

Cytoreductive surgery and chemotherapy are the mainstays of treatment but the median survival of around two years has hardly changed in decades. The latest Gynecologic Oncology Group study in the USA, involving Taxol in combination with cisplatin, has shown a wholesale change in survival, with a median to date of 37 months and represents an encouraging leap forward in this disease. This has been confirmed by the Intergroup study which first reported in May 97 with a disease-free survival advantage of 4.5 months, followed last May by an unexpected overall survival advantage of 10 months. Now there are several active agents in the treatment of cancer of the ovary and their use in the initial management of the disease will be clarified in the next 5-10 years.

Surgery

Gynaecological oncology has only become established as a subspecialty of obstetrics and gynaecology within the UK in the past decade or so. In that time the surgical management of ovarian cancer has become refined. Within clinical and particularly medical oncology (as the treatment is very largely confined to chemotherapy) only a small number of consultants declare a special interest.

Known as debulking, surgery aims to reduce the volume of disease as far as possible and should include bilateral salpingo-oophorectomy and total abdominal hysterectomy, omentectomy and, where possible, lymph node biopsy.

Chemotherapy

Current ‘ gold’ standard

Relapse therapy                                                                           Depends on treatment-free interval. Might include:

Developments in treatment


Hilary Thomas
Professor of Oncology, Royal Surrey County Hospital and University of Surrey



Secondary navigation