Borderline ovarian tumours

Borderline ovarian tumours are abnormal cells that form in the tissue covering the ovary. They are not cancer and are usually cured with surgery.

What are borderline ovarian tumours?

Around 15 out of 100 ovarian tumours (15%) are borderline tumours. They are sometimes called atypical proliferative tumours or tumours of low malignant potential.

They are different to ovarian cancer because they don't grow into the supportive tissue of the ovary (the stroma). They usually grow slowly and in a more controlled way than cancer cells.

Borderline tumours usually affect women aged between 20 and 40. They are usually diagnosed at an early stage. This means the abnormal cells are still within the ovary.

Sometimes abnormal cells break away from the tumour and settle elsewhere in the body. This is usually in the tummy (abdomen). Very rarely, these cells start to grow into the underlying tissue.

The main treatment for borderline tumours is surgery. Most women are cured and have no further problems. There is a small risk of the tumour coming back. Very rarely, the borderline tumour cells change into cancer cells.

Types of borderline ovarian tumour

There are different types of borderline ovarian tumours.  Around 50 out of 100 borderline tumours (around 50%) are serous type. Around 45 out of 100 borderline tumours (around 45%) are mucinous type.  

Other rare types include:

• endometrioid
• clear cell
• seromucinous
• borderline brenner tumours

Symptoms of borderline ovarian tumours

Small borderline tumours don't usually cause symptoms. Doctors might find the tumour while you're having tests for something else.

Larger or more advanced borderline tumours might cause symptoms.

Symptoms can include:

• pain or a feeling of pressure in the tummy area (pelvis or abdomen)

• a swollen abdomen

• pain during or after sex

• vaginal bleeding not related to your period

Tests for borderline ovarian tumours

If you have symptoms, your doctor will examine you and can refer you to the hospital for a scan. 

Pelvic examination

Your doctor is likely to press gently on the outside of your tummy (abdomen) while you are lying down. They are feeling for any lumps, or tender areas.

Your doctor might also examine you internally. This is to see if your womb and ovaries feel normal.

Your doctor will ask you to lie on your back on the couch with your knees up and legs apart. They put one or two gloved fingers into your vagina, and at the same time press down on your tummy (abdomen) with their other hand. They may be able to feel if there are any swellings or lumps in your ovaries or womb.

Scans

You might need to have an ultrasound scan. An ultrasound uses sound waves to build up a picture of a part of the body. You might have an abdominal ultrasound or a transvaginal ultrasound, or both.

Surgery

If you have a lump (mass) on your ovary, you will need an operation to find out what it is. Your surgeon might remove part or all of your ovary. A specialist carefully looks at this under a microscope.

Staging for borderline ovarian tumours

Staging shows the size of the tumour and whether it has spread. Doctors use the same staging system for borderline tumours as for ovarian cancer. There are 4 stages, from 1 to 4:

• stage 1 is the earliest stage where the borderline tumour is within the ovary
• stage 2 generally means the abnormal cells have spread within the pelvis, for example to the womb, fallopian tubes, bladder or the back passage (rectum)
• stage 3 means the cells have spread outside the pelvis into the abdominal cavity
• stage 4 is the most advanced. It means the cells have spread to another part of the body, such as the lungs

Most borderline ovarian tumours are stage 1.

Treatment for borderline ovarian tumours

Surgery is usually the only treatment you need for a borderline ovarian tumour. The surgery you have depends on:

• where the tumour is and whether it has spread

• whether you want to have children

Your doctor will talk through the options of surgery with you. 

If you’ve had the menopause

Your doctor (gynaecological oncologist) removes:

• both ovaries and fallopian tubes
• the womb, including the cervix

This operation is called a total abdominal hysterectomy (TAH) and bilateral salpingo oophorectomy (BSO).

If you’re still having periods

Your gynaecological oncologist may remove just the affected ovary and fallopian tube if:

• the tumour is only within the ovary
• you plan on having children in the future

The surgery

During the operation your doctor will closely look at the inside of your pelvis and abdomen. And take samples. This is to check for any signs that the tumour has spread.

They might also remove part of the fatty tissue close to your ovaries called the omentum.

If you have a mucinous type of borderline ovarian tumour, your doctor might also remove your appendix. This is because mucinous tumours can sometimes start in the appendix. And then spread to the ovary.

Most women are cured with surgery. If a borderline tumour does come back, you have more surgery. Your doctor will talk to you about the type of surgery you need.

We have information about having a hysterectomy in the ovarian cancer section. Remember this section is about ovarian cancer. So some of the information may not be relevant.

Follow up

Follow up appointments are to check how you are and whether you have any problems. You might have scans to check if the tumour has come back (recurrence). Most borderline ovarian tumours don’t come back.

Your healthcare team will discuss with you how often you need follow up. This depends on:

• the surgery you had

• whether the tumour had spread away from the ovary when you were diagnosed

• the type of borderline ovarian tumour you had

Coping

Being diagnosed with a borderline ovarian tumour can be a confusing and difficult time. It is usual to feel a wide range of emotions.

Talk to your doctor or gynaecology specialist nurse about how you are feeling. They can also help to answer any questions you might have.