Glasgow, United Kingdom: Researchers have developed a non-invasive test that detects cervical precancerous lesions by analyzing urine and vaginal samples collected by women themselves.
In his speech at the 2019 NCRI Cancer Conference held today (Monday), Dr. Belinda Nedjai stated that the self-sampling test is very popular among women participating in this study, which means that it may improve cervical cancer screening programs. Participation.
"The initial use of self-sampling may be for women who have not accepted a screening invitation to see a doctor and countries that do not have a cervical cancer screening program. In the long run, self-sampling may become the standard method for all screening tests. The study shows that women prefer to do examinations at home than doctors at home.” Dr. Nedger said He is a senior researcher in epidemiology and director of the Laboratory of Molecular Epidemiology, University of Mary, London, UK.
"As far as we know, this study is the largest test of methylation classifiers (called S5) in urine and self-collected cervical samples to detect precancerous lesions in women who are referred for further study.- Sampling tests to increase the acceptance rate of cervical cancer screening, reduce the cost of health services and improve the performance of the screening program."
The gold standard Pap smear currently performed in the clinic is a positive test for human papillomavirus (HPV).
Dr. Nedjai said: “HPV testing is rapidly becoming a global primary screening method for cervical cancer. It is a very sensitive method. It is very good at detecting true positives, but lacks specificity-in other words, the second test needs to exclude HPV positives. . Women who are not susceptible to cancer. Choosing the right strategy for high-risk HPV positive women is a key issue.
The S5 test developed by Dr. Nedjai and her colleagues at Queen Mary University measures DNA methylation-chemical changes to one of the four basic letters of DNA that make up the human genetic code. S5 observes the DNA methylation of the four HPV types most related to cancer-HPV16, HPV18, HPV31 and HPV33-and the human gene EPB41L3 to generate a score that indicates the level of risk. If the score is higher than the selected cutoff value, it indicates an increased risk of precancerous lesions, and the higher the score, the higher the risk of cancer. They found in an earlier study that when S5 was used on cervical samples, for women who tested positive for HPV, S5 could accurately detect invasive cervical cancer, while 93% could accurately detect precancerous lesions.
Before cervical cancer, abnormal growth of precursor cells on the surface of the cervix-so-called cervical intraepithelial neoplasia (CIN) or precancerous stage-may develop into cervical cancer. It is divided into three stages (CIN1, CIN2, and CIN3), and the probability of cells developing into cancer in each stage increases.
Dr. Nedjai said: "We decided to evaluate whether S5 can identify women with CIN3 precancerous lesions through urine and vaginal samples."
Women attending the colposcopy clinic of the Royal London Hospital due to an abnormal smear test or a positive HPV result were asked to participate in a study led by Professor Jack Kuzk, director of the Wolfson Institute of Preventive Medicine at Queen Mary University. A total of 620 women provided vaginal samples and collected themselves using vaginal swabs, of which 503 women also provided urine samples. The researchers extracted and analyzed DNA in the laboratory, and produced an S5 score.
Dr. Nedjai said: “We found that the S5 classifier works well in urine and vaginal samples regardless of whether HPV testing is performed.” “It distinguishes women without precancerous lesions from those with CIN3 or higher lesions. Women. We evaluated two different methods that can use S5. We first tested S5 as an auxiliary test for HPV-positive women to limit the number of patients in the urine. S5 can better identify those who do have precancerous lesions. Women, instead of testing for the presence of HPV16 or 18; compared with S53, the true CIN3 recognition rate is 96%, and HPV16 or 18 test is 73%. Secondly, we evaluate S5 as an independent test without first performing an HPV test. We adjusted the threshold to identify at least 85% of true positives, urine and self-collected vaginal samples.
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