An extra test of cervical smears will make national screening for cervical cancer more reliable and less burdensome for patients. This has been revealed by PhD research by Nan Yang. Yang will be awarded a PhD in Medical Sciences by the University of Groningen on 25 January 2010.
Every year, about six hundred Dutch women develop cervical cancer. In order to discover the disease at an early stage, Dutch women between the ages of thirty and sixty are invited once every five years to participate in national screening by having a cervical smear done. Lab technicians and pathologists examine the cells the cervical smear yields to see whether they are aberrant in any way, which could point to an early stage of cervical cancer.
However, a small group of women test false positive: the cells appear to be aberrant under the microscope, yet the women do not have cervical cancer. Only a more comprehensive examination (colposcopy) of the external orifice of the uterus will show whether the women have cervical cancer or not. There are also false negative tests, where patients with an anomalous cervix are missed.
In her PhD research, Nan Yang discovered that a DNA test that can be easily carried out on the smears already taken would make the national screening for cervical cancer more reliable. The so-called DNA methylation test can be used on smears which seem to have suspicious cells. The methylation test shows whether certain cancer-suppressing genes have been rendered inactive by a methyl group. If that is indeed the case, this indicates an early stage of cervical cancer. The methylation test can analyse hundreds of smears simultaneously. Women whose smears seem suspicious under the microscope and who have an anomalous methylation pattern can then be quickly referred to the gynaecologist to have their external orifice examined (colposcopy) and can then be treated during the same procedure. This means that patients are saved one trip to the hospital and are treated sooner.
The methylation test can also be used in combination with a test for the virus that causes cervical cancer, the so-called human papillomavirus (HPV). This could mean diagnosing the disease at an earlier stage. Further research must show whether the methylation test could become more sensitive if more genes were to be tested. Methylation also still has to prove its worth on a large scale in the current national screening.
Nan Yang (China 1979) did her PhD research at the departments of Obstetrics & Gynaecology and Pathology at the University Medical Center Groningen within the GUIDE research school. Her research was funded by the Dutch Cancer Society (KWF) and the companies Oncomethylome Sciences (Liège, Belgium) and Pantarhei Devices BV (Zeist, the Netherlands). Her thesis is entitled ‘Detection of DNA hypermethylation as a diagnostic tool in cervical neoplasia’. Her supervisors are Prof. A.G.J. van der Zee and Prof. H. Hollema.
Contact: the University Medical Center Groningen press office, tel. +503612200
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