Low grade serous ovarian cancer

What is low grade serous ovarian cancer?

Low grade serous ovarian cancer (LGSOC) is a form of ovarian cancer that is invasive and grows slowly on surface tissue.

Unlike other more common forms of ovarian cancer its cells are more like normal body cells, but this means it is less likely to respond to chemotherapy.

It is a rarer form of ovarian cancer, usually found in people aged between 40 and 60. But it also affects other age groups. There are about 560 cases diagnosed in the UK each year.

Between five and 10 per cent (one in 20 and one in 10) of people thought to have the most common form of ovarian cancer, which is epithelial serous ovarian cancer, are found to have low grade serous ovarian cancer (LGSOC). Up to 20 per cent (one in five) of those diagnosed with advanced, serous borderline tumours go on to develop low grade serous ovarian cancer.

Low grade serous ovarian cancer does not develop into high grade serous ovarian cancer apart from in exceptional cases.

Symptoms

Diagnosis

It is thought to start in the ovaries or fallopian tubes and is usually at stages 2 to 4 when it is diagnosed, meaning that it has spread away from the fallopian tubes and ovaries into the pelvis and then the abdomen. You can find more information on the stages of ovarian cancer in Ovacome booklets on stage 2, stage 3 and stage 4.

Low grade serous ovarian cancer is diagnosed using clinical examination which may include a pelvic examination, ultrasound, and CT scans.You should be offered a CA125 blood test which can detect a protein in the blood that is a cancer marker.

If you are found to have symptoms and the CA125 test comes back at a level of 35 or above, you should be referred for a scan within two weeks. It is important to know that CA125 levels in those with low grade serous ovarian cancer may be less than the threshold level of 35

How is low grade serous ovarian cancer treated?

If surgery is not possible straight away, perhaps because you are too ill, you may be offered chemotherapy then surgery followed by further chemotherapy. If surgery is not recommended, you may be treated using other therapies such as hormone therapies.

Chemotherapy

If surgery is not possible straight away, perhaps because you are too ill, you may be offered chemotherapy then surgery followed by further chemotherapy. If surgery is not recommended, you may be treated using other therapies. You may be offered hormone therapies.

After surgery, low grade cancer that has advanced further than stage 1 is usually treated with chemotherapy, although low grade does not respond to this as fully as other forms of ovarian cancer.

You may be offered the chemotherapy drug carboplatin on its own or in combination with a second chemotherapy drug called paclitaxel. Because low grade serous ovarian cancer is less responsive to chemotherapy, you may be offered Avastin (bevacizumab). This is a targeted therapy that affects the blood supply to cancer cells. It can be used alongside chemotherapy.

After your chemotherapy you may be offered medication such as letrozole or anastrazole that reduces the amount of the female hormone oestrogen in your body. This is because oestrogen can encourage the growth of low grade serous ovarian cancer. These drugs can be taken long term as maintenance therapies.

Research has shown that using these hormone therapies after first line chemotherapy can keep the disease controlled for longer. You can find out more about chemotherapy here.

Recurrence

Most people diagnosed with low grade serous ovarian cancer experience a recurrence at some point.

It may be possible to treat this with further surgery. If you have had a long period of being cancer-free, if the cancer has come back in just a few places and if you do not have ascites (a build-up of fluid caused by the cancer which can lead to abdominal bloating) then surgery may be an option. After surgery you may be offered hormone therapy.

If you have a recurrence your condition may be managed using chemotherapy including Caelyx and paclitaxel, hormonal therapies and targeted therapies which are drugs that target cancer cells which have specific changes.

Research has also shown that a drug called trametinib, a MEK-inhibitor, can be an effective treatment for low grade serous ovarian cancer. A US/UK trial called GOG281/LOGS involved 260 women with recurrent or progressive cancer. It showed that trametinib reduced disease progression by 52 per cent (52 in 100) compared to other treatments such as letrozole, tamoxifen or chemotherapy.

Treatment with trametinib made it four times more likely that LGSOC would respond to therapy and showed a trend towards overall survival benefits.

In England, trametinib is routinely available as an option for adults with recurrent or progressive low grade serous ovarian cancer, it is off-label so not currently licensed for this use. This is for people who have received platinum-based chemotherapy previously and have not had treatment with a MEK-inhibitor in the past.

In Scotland trametinib is available for patients with low grade serous ovarian carcinoma after at least one line of platinum-based chemotherapy. In Wales and Northern Ireland access to trametinib can be discussed with your consultant. You can find out more about treatment with a recurrence here.

Katie says:

"I remember being confused by this dichotomy and realise now that the way cancer is portrayed in the media and online isn’t everyone’s reality.
Yes, it’s terrifying, and awful, and a million other emotions, but there are things that I would never have done, or people I would never have met had it not been for cancer”

Katie was diagnosed with low grade ovarian cancer in April 2020. Here she shares her experiences. 

Read Katies story

Join Ovacome’s rarer ovarian cancer support group

Meet others in a similar situation to you in this online support group. Click here to read more and register.

Read more

Did you find this page helpful?

We welcome your feedback. If you have any comments or suggestions, please email r.grigg@ovacome.org.uk or call 0207 299 6653.