Ovarian Cancer Screaning

Thomas Ind
Consultant Gynaecological Surgeon
Royal Marsden & St George's Hospital

51 Sloane Street & 149 Harley Street

Tel:020 7201 2666; Fax: 020 7823 1499

Ovarian cancer screening

Introduction

Ovarian cancer accounts for about 4000 deaths in the UK every year. It is often called ‘the silent killer’ as it is usually detected late when treatments are less effective. Ovarian cancer screening (OCS) may be requested from women who have a strong family history of ovarian cancer and other women who are just worried. The role of OCS has not yet been defined and there are a number of unanswered questions that a woman who wishes to be screened needs to be aware of. This leaflet aims to answer some of these questions.

Who is at risk of ovarian cancer?

Most ovarian cancers occur spontaneously. Women whose periods start early and end late late in life are at slightly more risk. About 5% of cancers occur in women who have inherited a predisposition. Therefore, women who have a family history are at increased risk (see back of leaflet). Women with two or more affected first degree relatives (sister, daughter, or mother) are at particular risk. Women with affected second degree relatives (Grandparent or Aunt) have a small increased risk.

The evidence for screening

The evidence for screening is not clear-cut. Screening misses a significant proportion of cancers and can detect non-cancerous cysts resulting in unnecessary surgery.

At present, women with a ‘population risk’ (see below) are not advised screening. This is because it is not clear if screening is more likely to give a ‘false positive’ result. There is a large national study looking at this and until the results are made public, the value is not known.

Screening for women in the ‘high risk’ group (see below) is thought to be of benefit and is currently offered in some units on the National Health Service. However, the evidence for the value of screening is not 100% and screening is not universally available. The value of screening for women in the ‘increased risk’ group (see below) is more controversial. However, most specialists are prepared to offer this after careful counselling.

Women in the ‘very high risk’ group (see below) are normally advised to have their ovaries removed in their early forties.

What happens during screening?

The screening process involves one of three types of visit (Initial Visit, Annual Screen, Interval Screen).

The Initial Visit involves a consultation with a consultant to establish an individual woman’s risk. The screening process is then explained including the possible disadvantages. If following that initial consultation a woman wishes to continue, she has a blood test and an ultrasound scan. The ultrasound scan utilises a probe that passes through the vagina to help visualise the ovaries. These are not always seen but failure to identify the ovaries on scan is interpreted as being a good sign. The blood test is for a protein in the blood called CA125. This protein increases with ovarian cancer in addition to other conditions.

An Annual Screen occurs every subsequent year and involves the blood test and scan only.

Results are relayed to women over the phone. They are informed that they require an Annual Screen in another year or an earlier appointment (Interval Screen). An Interval Screen is the same as an Annual Screen but occurs more frequently when there is concern over a scan or blood result.

Ovarian cancer prevention

Ninety eight percent of ovarian cancers can be prevented by an operation performed through telescopes where the ovaries are removed. This does not give 100% protection as ovarian cancer can develop from cells in the sac that surrounds the ovary and other internal organs called the peritoneum.

Women who take the pill for five years have a 60% protection against ovarian cancer and this form of treatment can be used in women reluctant to undergo surgery.

Ovarian cancer risk groups

Very High Risk (>30%)

BRCA1 & BRCA2 carriers

High Risk (>15%)

Family contains 2 or more individuals with ovarian cancer who are 1st degree relatives
The family contains 1 individual with ovarian cancer and 1 individual with breast cancer diagnosed under 50 who are 1st degree relatives
The family contains 1 individual with ovarian cancer and the participant has had breast cancer before the age of 50
The family contains 1 individual with ovarian cancer and 2 individuals diagnosed with breast cancer before the age of 60
The family contains 1 individual with ovarian cancer, 1 individual with breast cancer before the age of 60 and the participant herself has had breast cancer before the age of 60
The family contains 1 individual with ovarian cancer and at least 3 with colo-rectal cancer of which one must be under the age of 50 at time of diagnosis.
The family contains an affected individual with one of the known breast cancer predisposing genes

Increased Risk (1 – 5% increase)

One first degree relative with ovarian cancer
One first degree relative with breast cancer before the age of 50
Personal history of breast cancer before the age of 50

Population risk (0.8%)

No family history or no 1st degree relatives