By Paul Nicolaus
December 14, 2023 | Hong Kong-based HKG Epitherapeutics, along with McGill University in Canada, announced new data on the ability of a test to detect cervical cancer sooner than traditional screening methods by looking at changes in four specific genes. “The goal was really to find if we could use these markers of DNA methylation to predict progression of cervical cancer,” Mariam El-Zein, an epidemiologist and associate director for research in the division of cancer epidemiology at McGill University, told Diagnostics World.
A growing body of evidence suggests that epigenetic changes are associated with abnormal alterations in the cells lining the cervix and could help predict the risk of cervical cancer, she and colleagues explained in a paper published in the International Journal of Cancer (DOI: 10.1002/ijc.34686). Their study examined several epigenetic markers (CA10, DPP10, FMN2, and HAS1) discovered using a genome-wide methylation approach. Results demonstrated the ability of a test called epiCervix to identify patients with premalignant and malignant cells.
Using a threshold of 100% specificity, the sensitivity for detection of cervical cancer was 68%. When specificity was reduced to 95%, sensitivity increased to 84%. To arrive at their findings, the researchers selected different grades of cervical intraepithelial neoplasia from two independent study populations recruited at two different times, in addition to using publicly available datasets.
Although CA10 and HAS1 have previously been associated with other forms of cancer, to their knowledge, they have not yet been tied to cervical cancer. The researchers indicated that their work “demonstrated the reproducibility” of the four markers examined and that they see these as “promising molecular markers” in cervical carcinogenesis. Furthermore, they see potential for a test that could be used to screen for this form of cancer.
“Our findings have clear implications for clinical practice,” they concluded. “Our discoveries can be implemented in high-throughput assays for clinical and public health use via NGS and DNA methylation to devise an affordable methylation analysis test.” Whereas existing DNA methylation assays used for cervical neoplasia screening largely rely upon quantitative methylation-specific PCR-based assays to target different gene regions, the researchers noted that the scalability and speed of NGS could help save on time and resources.
Barriers Remain Despite Existing Screening Tests and Vaccine
Nearly every case of cervical cancer is linked to infection with high-risk human papillomaviruses (HPV), which are transmitted from one person to another through sexual contact. Over the course of their lives, at least half of all sexually active people will have HPV at some point. Most of these infections wind up resolving spontaneously without symptoms. However, long-lasting infection can potentially lead to cervical cancer.
Cervical cancer is unique in the sense that there is a known causative agent (high risk HPV strains) for the vast majority of all cases, there exists an effective screening test (Pap smear and HPV DNA test), and there is an effective and publicly available preventative vaccine, explained June Hou, OB/GYN and associate professor of obstetrics and gynecology at Columbia University Irving Medical Center, who was not involved with the International Journal of Cancer study.
Even so, it remains one of the most common cancers affecting women worldwide for a variety of reasons, she told Diagnostics World. In its early stages, cervical cancer oftentimes does not cause noticeable symptoms. This lack of obvious warning signs is one reason why regular screening is so crucial, yet education and awareness remain an ongoing issue considering not all women are aware of the importance of screening or how often it should be done, especially following childbearing or menopause.
Social and cultural barriers present another challenge; in many areas around the world, there can be a stigma tied to cervical cancer screening. And while the HPV vaccine can help prevent most cervical cancers, Hou indicated that some women may mistakenly assume it eliminates the need for screening.
She also pointed out that low-resource settings experience barriers to screening—and so do countries with more extensive medical resources. “Many low and middle-income countries and enclaves do not have systematic screening programs, leading to late diagnosis and reduced survival rates,” Hou said. But even in a developed country such as the United States, access to screening programs remains an issue. Factors like lack of health insurance or inability to afford the out-of-pocket costs can prevent regular screenings. So, too, can issues like living in a remote region with few health care facilities or running into practical difficulties such as taking time off work.
Collectively, these types of barriers can contribute to a lack of compliance with regular, recommended Pap smears, which Monte Swarup, a board-certified OB/GYN and assistant clinical professor at Midwestern University (who was not involved with the International Journal of Cancer study) sees as one of the main challenges of catching cervical cancer. “Cervical cancer is a slow-growing disease, so if properly screened your healthcare provider will pick it up, likely in a pre-cancerous stage, which is amenable to treatment,” he noted.
Yet according to Eduardo Franco, professor and chair of the Department of Oncology at McGill University and Principal Investigator of the International Journal of Cancer study, there are limitations to this screening approach. “A traditional cytology test involves a cytopathologist observing specific cell types to screen for cancer, which is inherently subjective,” he said in a news release.
HPV DNA-based testing has added another tool—and one that is less prone to human error and misinterpretation of results—but there are still potential drawbacks. “The problem with existing cervical cancer screenings is that they don’t always catch malignant cells, and even if a woman has HPV, it doesn’t mean that she has cancer,” added Moshe Szyf, HKG Epitherapeutics CEO and co-author of the International Journal of Cancer study.
Accurately determining if a lesion is cancerous or not can be a considerable challenge at the premalignant stage, he told Diagnostics World. Although a predominant approach involves screening for carcinogenic mutants of HPV, he noted that “this method’s sensitivity is relatively low,” and sees a need for more advanced detection techniques at these early stages.
El-Zein explained that a woman could have a high-grade pre-cancer cervical lesion, but that lesion could eventually regress and become benign. So even if a woman tests positive, it doesn’t necessarily mean she will develop cancer.
She also highlighted the sense of uncertainty that the combination of a positive HPV test result and a normal Pap test result can cause. El-Zein sees a need—especially as some countries transition to HPV primary-based screening—to figure out how to effectively handle these patients. Should they go to colposcopy? Is a biopsy needed? Should they be told to come back?
Prospective Studies Needed for Further Validation
There has been an effort over the years to find more specific markers that could help identify patients in need of further follow-up and more aggressive treatment, El-Zein said, and she and colleagues believe a methylation test could help triage women by detecting alterations at the cellular level, which are early events in carcinogenesis.
HKG’s test offers an earlier warning system than today’s existing options, according to Szyf. Because the epiCervix test is more sensitive than traditional types of screening, it can detect cancer DNA among cells that appear noncancerous, he explained, making it possible for medical professionals to identify patients needing additional testing.
However, despite the promising possibilities seen within their new findings, the researchers acknowledged that prospective studies are needed to further evaluate the biomarkers detailed in their paper. One key caveat of the International Journal of Cancer study is that it was based on cross-sectional data, meaning they did not determine if the women’s lesions would eventually regress or progress.
“We validated that our markers could detect cancer in its early stage, but we really need to validate these findings in a prospective study where we recruit women and we follow them over time,” El-Zein said. This sort of study could reveal long-term fluctuations in methylation patterns and offer insights into the triage potential of the markers for use in primary HPV-based cervical cancer screening.
El-Zein said there are plans to build upon this line of research. The follow-up work would involve recruiting women in several colposcopy clinics and testing the study participants at every visit for the methylation markers to see how the methylation profile could predict the regression or progression of cervical lesions.
Beyond the use of surgical samples collected by a physician at the clinic, she said there is interest in exploring whether it would be feasible for women to collect their own cervical vaginal samples—or to use a urine sample—in hopes of eventually arriving at a less invasive testing option.
She explained that self-sampling has long been proposed, but it gained momentum during the COVID-19 pandemic as women stopped going to colposcopy clinics during the lockdown. One of the upsides would be the ability to reach women who have traditionally been more challenging to engage, such as the indigenous population or those who are reluctant to be seen by a male physician for religious or cultural reasons.
As she spoke of long-term plans and goals, El-Zein noted that Szyf’s vision is essentially the development of a simple test that could use the same sample to test for both HPV and methylation markers. Part of this vision is to wind up with a highly scalable test based on NGS so that many samples could be tested simultaneously using automated processes.
On the research side, meanwhile, she is focused on proving the validity of their approach. Eventually, the aim is for translational research that leads to tools that directly benefit women, she said, but at this stage further validation is still needed.
El-Zein’s forward-looking thoughts included mention of the possibility of an app that would use an algorithm to take into account various factors (like whether a person has been vaccinated against HPV and the presence or absence of methylation markers) and serve as a risk stratification tool to predict the likelihood of developing cervical cancer down the road.
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