NEW YORK (360Dx) – As molecular testing for human papillomavirus gains a foothold in cervical cancer screening, some believe self-collection of samples for testing may be not too far behind.
But even as a small movement for sample self-collection gathers momentum, not everyone thinks such a procedure is ready for widespread adoption.
Self-collected samples for Pap and cytology testing was the subject of a US Food and Drug Administration workshop in January, in which a group of experts presented perspectives on the potential for self-collection of specimens from the cervix for the purposes of liquid-based Pap testing. The objective of the workshop was to provide a forum where members could discuss the feasibility and risks of self-collection of specimens for Pap testing.
One expert who testified at the workshop, Mark Schiffman, a senior investigator at the National Cancer Institute, told 360Dx that self-collecting samples for testing could be vital for women who are unable to participate in cervical cancer screening, but it should be done only in conjunction with highly sensitive molecular tests.
"Self-sampling for HPV molecular tests is extremely promising and may end up being the dominant approach taken for cervical cancer screening throughout the world in the years ahead," Schiffman said. "I see the workshop as clearing the clutter of thinking to conclude that it is not useful to self-sample for Pap testing and cytology, but it could be useful to self-sample using the new molecular methods, because we need to expand screening."
Schiffman was among 14 experts in the field of cervical cancer, including the FDA and academic and professional organizations and involving researchers and practicing clinicians, who participated in the workshop.
During a routine Pap testing procedure, cells from the cervix are gently scraped away and then examined for abnormal growth. The procedure is usually done by a clinician who can access a sample that is broadly representative of cervical cells in a target region where most cancers begin and then examine the sample under a microscope.
A molecular HPV test, in contrast, looks not for cellular changes, but instead for the type of virus, and, said Schiffman, "testing for the causal agent and its state through molecular methods is more reproducible, sensitive, and accurate. … Detecting carcinogenic HPV types provides better predictive value, provides reassurance that a result is negative, and gives more insight into what's going on than cytology."
Still, clinicians generally are not ready to move to molecular testing alone, even before they think about implementing self-collection for molecular testing, according to Schiffman and other workshop participants. An expert panel noted that any self-collection devices for Pap testing would need to be held to the same standards as Pap testing performed in the clinic.
The standard of care for cervical cancer screening is well-established in the US. An automated liquid-based Pap test has largely replaced the conventional Pap smear method, and liquid-based cervical specimens can be used for both a Pap test and a molecular HPV test.
Specimen collection devices, such as a cervical broom or cervical spatula and brush combination, can be used by healthcare professionals to collect cervical specimens and then sent to a CLIA-certified laboratory for processing for Pap test and HPV testing. The results of these tests are returned to the ordering clinician who conveys the results to the patient and initiates appropriate treatment.
In underserved populations, self-collection devices could improve care, the workshop panelists noted. But some members voiced concerns about reduced accuracy compared to testing by clinicians. Paul Staats, an associate professor of pathology at the University of Maryland, said at the workshop that the vast majority of cervical cancer occurs in a small region called the transformation zone of the cervix. The self-collecting device must be capable of accessing this region, and for a test result to be accurate, a woman who is self-collecting must target that zone, he said.
Clinicians use a speculum so that they can see what they're targeting, but "if you're self-collecting, you're not going to have that visual assessment," he added.
At the workshop, Mona Saraiya, a medical officer at the US Centers for Disease Control and Prevention, said that although cervical cancer is preventable, each year in the US, there are about 12,000 new cases and about 4,000 women die from the disease. At least 93 percent of these cases could be prevented with a combination of screening and vaccination, she added.
According to Schiffman, a very small percentage of all HPV cases progress to cancer. The body clears almost all cases in two to three years, but some viruses can dwell in the body for decades, and, if left undetected and untreated, progress to precancer and cancer.
The prevalence of cervical cancer, he noted, is highest in low- and medium-resource countries and in low- and medium-resource settings in developed countries.
In recent years, several firms including Roche, Hologic, and Qiagen have received regulatory approval from the FDA for their molecular HPV tests. This past February, the FDA granted premarket approval to a Becton Dickinson molecular test to detect 14 high-risk types of human papillomavirus.
While no self-sampling HPV technology has been approved or cleared in the US, one such device has been OK'd in China. After receiving approval from the China Food and Drug Administration last June for a sequencing-based HPV test that relies on self-sampling technology for screening women for cervical cancer, BGI is targeting the test at women in rural areas of China.
In the UK, a company called Syrona Women has launched with the idea of providing women with not just sample self-collection technologies but with at-home tests for cervical cancer, as well as for sexually transmitted diseases and endometriosis.
Schiffman said that now that highly sensitive tests can measure HPV at the molecular level, there is a real question as to why clinicians would use Pap testing and cytology. Such highly sensitive tests would also enable the potential of self-collection, he said, because they could compensate for sampling challenges that are a concern for Pap testing.
In September last year, USPSTF issued draft recommendations for women aged 30 to 65 to be screened for cervical cancer either every three years using a Pap smear, or every five years with high-risk HPV testing alone. Previously, the USPSTF had recommended that HPV testing at five-year intervals should be done as part of a co-test that included a combination of cytology and high-risk HPV testing.
In the US, although clinicians are moving increasingly toward HPV molecular screening, whether co-testing — combining cytology and HPV molecular testing — is cost effective compared to HPV molecular testing alone does not have an easy answer, Schiffman said.
Should molecular testing become the norm, self-collection sampling methods could become more routine, particularly in areas where healthcare resources, such as labs and clinicians, and experts in cytology, histopathology, and colposcopy, may be in short supply, he said.
Further, with use of a point-of-care test, large numbers of women could provide self-collected samples to health centers, and know within an hour whether they need to have a visual follow-up exam. If that exam provides an abnormal result, she can be prescribed a low-morbidity treatment, he said.