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Ovarian cancer

Ovarian cancer accounts for 4% of female cancersCancer of the ovaries accounts for about 4% of cancers in women, with approximately 235,000 cases worldwide in 2012ANCHOR. The five-year survival rates for ovarian cancer have doubled in the past 30 years and are now roughly 40%, although this depends on the age of the patient and stage of the cancerANCHOR ANCHOR ANCHOR. This is due to the greater use of platinum-based compounds and greater effectiveness in treating recurrent cancers.

Potential treatments


A blood test for elevated levels of the protein CA125 is used to inform doctors if ovarian cancer is present and how it is responding to treatment. CA125 is a protein made by some ovarian cancer cells and it is the most common biomarker used for detecting ovarian cancer. As the test has a high false positive rate, it is generally not recommended for women with an average risk of ovarian cancer. It is often used for those with higher risk or are presenting symptoms consistent with the disease. CA125 was first discovered using a mouse monoclonal antibody in 1981. The protein was named cancer antigen 125 because it was the 125th antibody produced against the ovarian cancer cell line that was being studiedANCHOR.

For women with a family history of breast or ovarian cancer, doctors can offer tests for forms of genes that are linked to these cancers. The main genes associated with these are BRCA1 and BRCA2, which help to suppress tumours from developing and growing. The way this happens has been extensively studied and understood through experiments on miceANCHOR ANCHOR ANCHOR.


The main treatments for ovarian cancer are carboplatin (Paraplatin) and Taxol (paclitaxel).

Taxol (paclitaxel) was one of the first drugs to treat ovarian cancer and is found in the bark of the Pacific yew tree. It was discovered through a large project of cataloguing chemicals found in plants and animals for their anti-cancer properties. The chemicals isolated from these plants were screened against cancer cells for signs of activity and the yew tree extract was noted in 1965. Taxol was one of the most promising candidates found in the program, but its scarcity and unusual chemical structure meant that it received little attention. This was until 1979, when it was shown to have completely new mechanism for killing cancer cells and was capable of shrinking breast cancer tumours in nude miceANCHOR ANCHOR. Five years later, taxol was given approval for clinical trials, where it shrank tumours in 30% of women with ovarian cancer – an unprecedented success in treating this difficult diseaseANCHOR.

Carboplatin is a platinum-based drug and has fewer side-effects than the classic drug cisplatin, which was the first of this family of drugs. Cisplatin was originally created by accident while using platinum electrodes in electrolysis. It was the noted that cisplatin prevents cell division in bacteria and later its anti-tumour properties were discovered through experiments on miceANCHOR.

There are a range of other treatments that are available for more advanced or recurrent cancers. Among these is Avastin (bevacizumab), a humanised mouse antibody that slows the growth of new blood vessels. This helps to starve the tumour of oxygen and nutrients. Hormone treatments, such as tamoxifen, are being studied to see how effective they are in treating resistant ovarian cancers. These treatments are commonly already used in breast cancer treatment.

Potential treatments

In 2005, researchers discovered that cells missing either the BRCA1 or BRCA2 genes were very sensitive to a compound that blocked the action of PARP-1, a DNA repair proteinANCHOR ANCHOR. These cells were then transplanted into nude mice to check that the same effect was seen in vivo. Indeed, the PARP inhibitor blocked the growth of BRCA2-deficient tumours and had little effect on tumours without the mutation. Research also showed that genetically modified mice which did not have any PARP-1 were still healthyANCHOR. This indicated that there would not be any serious side effects when using a drug to block PARP in humans. This increased interest in the potential for PARP inhibitors as cancer drugs. There are now estimated to be 60 PARP inhibitors in development worldwide, with at least six phase III trials ongoing at the end of 2013ANCHOR.

Another approach is to target the CD44 protein, which helps cancer cells to grow out of control and develop resistance to standard treatments. Researchers have successfully used small, inhibiting RNA molecules to block the CD44 gene from functioning in mice, which shrinks their tumoursANCHOR.


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Last edited: 21 October 2014 12:46

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