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Ovacome is a national charity providing support to anyone affected by 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.

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


What are borderline ovarian tumours?

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. 

Small borderline tumours don’t always cause symptoms. They are sometimes found in tests for other conditions. Larger borderline tumours may cause pain or pressure in your pelvis or abdomen, abdominal swelling, painful sex and vaginal bleeding that is not a period.

A diagnosis of borderline ovarian tumour can be confusing, because you are treated by cancer specialists, but it is not a cancer diagnosis. Most cases of ovarian cancer are found at an advanced stage (stage 3 or 4). This is when the cancer has spread beyond the ovary.

Because borderline tumours behave in a much less aggressive way, in most people the condition has not spread beyond the ovary when it is diagnosed (stage 1 disease). This means that for those who have had surgery to remove early disease, the risk of it coming back is very small at less than five per cent (five in a hundred).

Most experts recommend that no special follow-up is needed after surgery for stage 1 borderline tumours.


Read Victoria


Watch What are borderline ovarian tumours?, an Ovacome webinar with Professor Mona El-Bahrawy


More difficult cases

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

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

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

3. Stage 1 borderline ovarian tumours in young people 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 people with borderline tumours 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 “noninvasive 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 those with surface seedlings/noninvasive implants of borderline tumours, 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. 

For more information see Ovacome booklet Low grade serous ovarian cancer available here.


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 tumour, 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 people treated with limited surgery

If you are a young person 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 the tumour 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 those 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.


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Support for you

Ovacome is the UK 's national ovarian cancer support charity. We've been providing emotional support and personalised, expert information since 1996. Contact our support line by phone, email or text if you have questions about a diagnosis, or if you just want to talk things through.

We support anyone affected by ovarian cancer, including family members, carers, those with an inherited risk, and health professionals working in the field.

We run support group and events, both in person and online, providing an opportunity to connect with others. Find out more about our groups and events here.

Support line


If you would like more information on the sources and references for this page, or if you would like to discuss anything about ovarian cancer, please phone our support line on 0800 008 7054 Monday to Friday between 10am and 5pm.

Booklet text reviewed by Mr Andy Nordin, Consultant Gynaecologist / Subspecialist Gynae Oncologist, East Kent Gynecological Oncology Centre.

V.2.4. Last updated May 2023, due for review May 2026


Ovacome provides 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. Rights reserved.

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