Borderline ovarian cancer

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.

Borderline tumours make up around 15 per cent (15 in 100) of epithelial ovarian tumours. They are not cancerous or benign. Although borderline is not a cancer diagnosis, although you will be treated by cancer specialists

Symptoms

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.

Diagnosis and treatment for borderline ovarian cancer

A diagnosis of borderline ovarian tumours 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), 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).

Due to this, most people who develop borderline tumours are completely cured by surgery and never need any more treatment. 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).

More challenging 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.

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. You can read more about low grade serous ovarian cancer 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.

Jemima says:

"I think it’s safe to say, I was shocked on my initial diagnosis. I am an otherwise fit and healthy 30-something year old woman who’s never really had any medical issues, so to find that I had a form of ovarian tumour was nothing more than shocking."

Jemima was diagnosed with a borderline ovarian tumour in 2016, aged 33. 

Read Jemima's story

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