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Ovacome is a national charity providing advice and support to women with ovarian cancer.  We give information about symptoms, diagnosis, treatments and research.  Ovacome runs a telephone and email support line and works to raise awareness and give a voice to all those affected by ovarian cancer.

This fact sheet is for women diagnosed with a borderline ovarian tumour, a form of cancer sometimes called a tumour of low malignant potential or borderline ovarian cancer (BOC) or borderline cyst. It describes the best care for the small group of women who have more difficult cases of BOC.

There is a glossary with this fact sheet to explain words you may not be familiar with.

If you are diagnosed with a borderline ovarian cancer you can feel confused and uncertain. However, most women who develop BOC are completely cured by surgery and never need any more treatment.


What is borderline ovarian cancer?

Ovarian cancer develops when cells grow uncontrollably on the surface of the ovary and are able to spread to other organs.

Borderline tumours arise from the same type of cells, but their growth is much more controlled, and they are usually not able to spread.

Most cases of ordinary ovarian cancer are found at an advanced stage (stage 3 or 4). This is when the cancer has spread beyond the ovary. Because BOC behaves in a much less aggressive way, in most women the condition has not spread beyond the ovary when it is diagnosed (stage 1 disease).

This means that for women who have had surgery to remove early disease, the risk of it coming back is very small at less than 5 per cent. Most experts recommend that no special follow-up is needed after surgery for stage 1 BOC.


More difficult cases

There are three situations which can cause greater concern or uncertainty.

  1. Borderline ovarian tumours which have spread beyond the ovary.

  1. Mucinous borderline tumours involving the ovary, when tests suggest these could originate from a tumour in the appendix.


  1. Stage1 borderline ovarian tumours in young women treated with limited surgery to keep an ovary. There could be an increased risk of the disease coming back in the ovary you have kept.



Borderline ovarian tumours which have spread beyond the ovary

A small number of women with BOC have disease which has spread, in the form of little seedlings, onto the peritoneal membrane covering other organs in the abdomen.


Surface seedlings

Most of these seedlings do not invade the underlying tissue, but are just sitting on the surface. They are sometimes referred to as “non-invasive implants”. It is rare for them to cause problems, even if they stay after surgery.

We do not know the absolute correct way to care for women with surface seedlings/non-invasive implants of BOC, because research studies comparing different treatments (including observation) have not been performed.  The current guidance is that surgery should aim for complete removal of disease, including the peritoneum.

If the seedlings are invasive into the tissue of the peritoneum this is classified as low grade ovarian cancer.

Low grade ovarian cancer is also treated mainly using surgery although chemotherapy and hormone therapy may also be offered.


Mucinous borderline ovarian tumours

Most borderline ovarian tumours are classified as ‘serous’ from their appearance under the microscope.

A smaller number have a different appearance and are called ‘mucinous’.

Sometimes a small, undetected mucinous tumour can develop in the appendix, and spread to the ovary. This can give the appearance of a primary ovarian tumour, when in fact it is a secondary tumour.

It is important to consider this possibility in all cases of mucinous borderline ovarian cancer, so that a separate appendix tumour is not left behind at surgery.

It is difficult to decide the type of ovarian tumour (serous or mucinous) at the time of the operation. So surgeons must carefully inspect the whole abdomen, including the appendix, to look for a hidden primary tumour.

After surgery the pathologist may use special tests to tell apart a mucinous borderline tumour which has arisen from the appendix from one which was originally from the ovary.

Multidisciplinary teams dealing with ovarian tumours should always discuss these cases in detail, so they can make sure you receive the correct advice and treatment.


Stage 1 borderline ovarian tumours in young women treated with limited surgery

If you are a young woman with a borderline ovarian tumour, you may want to keep an ovary so you can have children. In this situation, a surgeon may remove the affected ovary, but leave the apparently normal ovary and uterus (womb). The surgeon must examine the abdomen carefully, to check if any cancer has spread.

In about 20 per cent (one in five) of these cases, the tumour comes back in the ovary that is left. This means you need regular check-ups after surgery.

Follow-ups may include ultrasound examinations every six months for about two years, then yearly. Later it may be appropriate for women who have had their family to have the remaining ovary removed. This removes the risk of problems in the future, and means they will not have to go for follow-ups.

If you would like more information on the sources and references for this fact sheet, please call us on 0800 008 7054.

If you would like to discuss anything about ovarian cancer, please phone our supportline on 0800 008 7054 Monday to Friday between 10am and 5pm.


Reviewed by Mr Andy Nordin, Consultant Gynaecologist / Subspecialist Gynae Oncologist, East Kent Gynecological Oncology Centre



Ovacome fact sheets provide information and support.  We make every effort to ensure the accuracy and reliability of the information at the time of printing.  The information we give is not a substitute for professional medical care.  If you suspect you have cancer you should consult your doctor as quickly as possible.  Ovacome cannot accept liability for any inaccuracy in linked sources.


Date last updated May 2018

Date for review May 2020




Removal of a small piece of tissue from an organ or part of the body so it can be examined under a microscope.


Treating a disease with medication, such as cytotoxic drugs (drugs that kill cancer cells).


Malignant tumours have the ability to invade and destroy surrounding tissues and can spread to other organs.

Mucinous tumours

Mucinous borderline ovarian tumours are a less common type of borderline ovarian tumour. They look different under the microsope, showing glandular structures.

Multidisciplinary Team

Several members of different hospital departments who meet to discuss the treatment plan for individual patients.


The branch of medicine that examines tissue from patients to determine diagnosis and treatment options.

Peritoneal membrane

Membrane that lines the abdomen and covers other internal organs.

Primary tumour 

The first cancerous tumour to develop in a particular part of the body.


Treating a disease with radiation.

Secondary tumour 

A tumour that involves a different place from where the cancer originally started (also called metastasis).

Serous tumours

Serous borderline ovarian tumours are the most common type of borderline ovarian tumour. They come from the surface membrane of the ovary and have a particular appearance under the microscope.

Ultrasound scan

Using sound waves to build up a picture of organs inside the body, through a probe placed on the abdomen or in the vagina.    


A layer of fatty tissue in the upper abdomen commonly involved in secondary ovarian cancer at the time of diagnosis.


The extent of cancer spread, which can range from stage 1, when disease is confined to the original organ, to stage 4, when there are secondary tumours involving other areas of the body. In ovarian cancer, stage 3 disease is commonly seen at diagnosis. This indicates that there has been secondary spread within the abdomen, involving the peritoneal membrane and / or omentum.


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