Researchers from the University of Oxford have identified a marker for ovarian cancer that could potentially lead to much earlier detection of tumours.
Currently the cancer is difficult to detect and usually found at a late stage. If ovarian tumours are detected early, however, they respond well to chemotherapy.
The researchers found that levels of a protein called SOX-2 were much higher in the fallopian tubes of patients with ovarian cancer.
Professor Ahmed Ahmed, the study’s lead author, said: ‘Ovarian cancer can be undetectable for up to four years and only a third of people with the cancer get an early diagnosis.
‘A test for SOX-2 could not only help detect cancers early but in some cases would enable us to detect a tumour before it becomes cancerous. Early treatment hugely improves the odds for patients, so early detection is essential.
‘However, there is still a lot of work to be done because detecting SOX-2 in the fallopian tubes is not an easy task.’
The researchers also discovered an enzyme called SIK2 in the omentum — an area of the intestines — that facilitates the spread of the cancer around the body, which makes it far more likely to be fatal.
Ahmed said: ‘We have found that ovarian cancer could only proliferate in the presence of an enzyme called SIK2, which has a role in “burning” fat to produce energy that is needed by the cancer cells to survive in the omentum.
‘We continued this study of SIK2 and found that levels of the enzyme were higher in secondary tumours in the omentum than in the related primary tumours in the ovaries.’
The study was published in EBioMedicine.
Ovarian cancer strikes one in 70 women and is the most deadly gynaecological cancer. Most patients are sadly diagnosed with it when they are stage 3, ie the cancer has spread from the ovary to the abdomen with multiple sites of involvement that include lymph nodes, the bowel, spleen and other organs. Overall patients at this stage have a five-year survival of less than 20 per cent.
Early detection of ovarian cancer has been fraught with difficulty. Unlike cervical cancer, which can be detected via Pap smear in the pre-malignant or early cancer stage, there is no specific screening test for ovarian cancer. Ultrasound only picks up discernible tumours which may have already spread.
CA125, a marker secreted by epithelial ovarian cancer, the most common type, is only produced once the cancer stage has been reached and only in 50 per cent of early stage cancers. Other markers are currently being investigated but have not been useful as they are usually detected once cancer is present.
The ultimate aim is a marker whose detection can indicate the presence of pre-cancerous cells.
This new study involved analysing cancer cells from multiple sites and comparing the expression of a gene called SOX-2 in those cells with that of fallopian tube cells.
The findings suggest that SOX-2 over-expression is characteristic not only of patients with epithelial ovarian cancer, but also in patients with BRCA mutations, which are known to increase the risk of ovarian cancer.