Clear cell carcinoma
What is clear cell carcinoma?
Clear cell carcinoma of the ovary is an uncommon type of epithelial ovarian cancer. It accounts for five to 10 per cent (five to 10 in a hundred) of patients with ovarian cancer in the western world, but 25 per cent (one in four) in East Asia (China, Japan, Korea, Mongolia).
It is likely that the cause of clear cell is different from the most common type of ovarian cancer, high grade serous epithelial ovarian cancer.
It may develop from other ovarian tumours called adenofibromas. A family history of clear cell ovarian cancer may also increase the risk and there is an association with Lynch syndrome which is an inherited condition that increases the risk of several cancers.
Clear cell ovarian cancer may also be more common in people with a history of endometriosis.
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Diagnosis
The symptoms of clear cell ovarian cancer are often experienced at an earlier stage than other types of ovarian cancer.
Those affected may notice a lump in their abdomen or experience pain or discomfort.
There is also an increased risk of developing deep vein thrombosis and pulmonary embolism (a blood clot in the lungs) which can be the first sign of the cancer.
The tumour marker CA125, which is measured in a blood test and used in the diagnosis of ovarian cancer, is not always raised in clear cell cancers so it may be less reliable.
Treatment for clear cell carcinoma
The first treatment is the same as for other more common forms of ovarian cancer. This means surgery; a total abdominal hysterectomy and bilateral salpingo-oophorectomy and omentectomy. This is the removal of the womb, cervix, ovaries, fallopian tubes, and omentum, a fatty sheet of tissue that covers the abdominal organs. This operation is sometimes referred to as a TAHBSO.
The lymph glands in the pelvis and the back of the abdomen may also be removed. They can show the stage of the cancer, meaning how far it has spread. Fluid from the abdomen will be tested for any cancer cells. A pathologist will examine the tissue and fluid removed to get more information about how advanced the cancer is.
After surgery you are likely to be offered chemotherapy using two drugs, carboplatin and paclitaxel (Taxol).
Where all the visible cancer has been removed, the aim of chemotherapy is to reduce the risk of the cancer coming back. When the tumour is more advanced and cannot be completely removed, the aim is to increase the time until the cancer returns and further treatment is needed.
Clear cell tumours respond less fully to chemotherapy than other ovarian cancers, so the benefit from chemotherapy may be less. You can find out more about chemotherapy here.
Fertlity sparing treatment
If the cancer is at stage 1a, which means it is within one ovary or fallopian tube and has not spread any further, it may be possible to have fertility sparing surgery. This is when the ovary and fallopian tube that are affected are removed, with the womb and other ovary remaining in place. This means a pregnancy may still be possible.
Current research
A trial that studied a different treatment to carboplatin and paclitaxel (Taxol) did not find any advantage so carboplatin and paclitaxel (Taxol) remain the standard treatment.
However, there is research which suggests that for people with clear cell cancer that is confined to the ovary (stage IA, IB and IC1) and where there has been an assessment of the pelvic and para-aortic lymph nodes, chemotherapy may be avoided. You will need to discuss the risks and benefits for your individual situation with your oncologist.
There is some research to suggest that radiation therapy (radiotherapy) is effective at protecting against recurrence. It also suggests that intraperitoneal chemotherapy (where it is delivered directly into the abdomen) may also be effective. This has not been accepted into routine clinical practice but you could discuss it with your consultant.
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A clinical trial is looking at nintedanib, an agent that targets tumour blood vessels. Another study is trialling a new immunotherapy drug pembrolizumab, and a further study is looking at an ATR inhibitor which blocks clear cell cancer cells’ DNA damage repair systems. We do not have the results of these studies yet.
If you are interested in taking part in a trial, discuss this with your oncologist. As clear cell cancers are rare, the trials are only open in a few centres but you may be able to be referred to one. You can find out more about trials here.
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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.
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