GLASGOW, United Kingdom — Instead of attending a clinic to have a Pap smear test, in the future women may be able perform a test at home to check for cervical cancer.
A British trial in 600 women showed that the home test, used on self-collected urine or vaginal samples, was able to identify those with precancerous lesions (stage 3 and above cervical intraepithelial neoplasia, CIN3+).
The home test, known as S5, measures four types of cancer-associated human papillomavirus (HPV) and the human gene EPB41L3 on self-collected samples.
The findings were presented here at the National Cancer Research Institute (NCRI) 2019 Cancer Conference.
The study "shows it's possible to detect cervical precancer that is at high risk of developing into invasive cancer in urine and vaginal samples collected by women in the comfort and privacy of their own homes," commented Manuel Rodriguez-Justo, MD, a consultant pathologist at University College London, UK.
He is a member of the NCRI's subcommittee on early detection and prevention, and was not involved in the trial.
"If the results of this study are validated by other groups, the implementation of urine-based testing and self-sampled vaginal samples will, potentially, increase uptake and reduce costs for the screening programs, whilst achieving high sensitivity to detect premalignant lesions," he said in a statement.
The home test for cervical screening made headlines in the British press, many of which quoted Robert Music, chief executive at the UK charity Jo's Cervical Cancer Trust, as saying the results could be a "game changer."
"It could mean those requiring treatment are identified faster and reduce the number of women having to go for potentially unnecessary investigations at colposcopy," he said in a statement.
Cancer Research UK, which funded the research, sounded a small note of caution in interpreting the study, putting the findings in context in a series of tweets.
The charity said that, although the study "is an exciting step forward," self-collected urine or vaginal samples are "not ready to be rolled out just yet." Some of the press reports suggest it will take at least another 3 years before such a test is available.
The charity also points out that "so far, the tests have only been used by people with advanced cervical cell changes that had already been picked up through existing screening tests."
For decades, cervical screening has been carried out with Pap smear tests, which involve a speculum being inserted into the vagina and a sample of cells being scraped off the cervix for testing in a cytology lab. Some women find this process uncomfortable, even painful, and some are put off from attending screening appointments by the invasiveness of the test.
In their abstract, the researchers say that "clinician-taken samples are the gold standard but self-sampling including urine may be a useful alternative."
"The initial use of self-sampling is likely to be for women who do not attend clinic after a screening invitation and in countries without a cervical cancer screening program," commented author Belinda Nedjai, PhD, senior research fellow and director of the Molecular Epidemiology Lab at Queen Mary University of London, UK.
"In the longer term, self-sampling could become the standard method for all screening tests. The study indicated that women much preferred doing a test at home than attending a doctor's surgery," she said in a statement.
For their trial, the team recruited women who were already attending a colposcopy clinic due to abnormal screening cytology and/or a positive HPV result.
The women were asked to provide a home urine sample using a standard device, and two self-collected vaginal samples using either Dacron (DuPont) and FLOQswab (COPAN Diagnostics), or HerSwab (Eve Medical) and Qvintip (Aprovix). Overall, the best-performing devices for vaginal self-samples were Dacron and Qvintip, the researchers report.
In all, 600 women provided vaginal self-samples, and 503 provided urine samples. These samples were then tested by the researchers with the S5 test. For comparison, all samples were also tested with the BD Onclarity HPV Assay (Becton, Dickinson and Co).
"We found that the S5 classifier with or without HPV testing worked well in both urine and vaginal samples," Nedjai said in a statement. "It distinguished between women who had no precancerous lesions and those who had CIN3 or higher lesions."
"We evaluated two distinct ways that S5 could be used," she continued. "We first tested S5 as a secondary test on HPV positive women to limit the number of patients sent to colposcopy. In urine, S5 was better at correctly identifying women who did have precancer lesions than testing for the presence of HPV16 or 18; 96% of true CIN3 were identified with S5 compared to 73% with an HPV16 or 18 test.
"Secondly, we evaluated S5 as a standalone test, without first doing HPV testing. We adjusted the cutoffs to identify at least 85% of true positives. Urine performed as well as self-collected vaginal samples," she said.
"We are currently working on new markers to try to improve the accuracy of the classifier even further…we think it's promising," Nadjai concluded.
The study was funded by Cancer Research UK. The study investigators have disclosed no relevant financial relationships.
National Cancer Research Institute (NCRI) 2019 Cancer Conference: Abstract 2451. Presented November 4, 2019.
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