There are significant barriers to cervical cancer screening in the U.S. and beyond. Sample self-collection promises to improve access to testing and treatment for cervical cancer patients.
By Jerome L. Belinson, MD
Summary:
The development of cervical cancer screening has evolved from cytology-based Pap smears to HPV testing, including innovations in self-collection and simplified testing methods that address screening challenges in low-resource regions.
Takeaways:
- Evolution of Screening Methods: The discovery of HPV as the cause of cervical cancer led to the development of molecular testing, which improved screening accuracy and facilitated self-collection.
- Self-Collection as a Game-Changer: Advances in PCR-based assays have made self-collection a reliable option, addressing screening barriers for underserved populations and those reluctant to attend clinical appointments.
- Global Impact and Innovation: Technologies like ScreenFire and Zebra Biodome are revolutionizing HPV testing by reducing costs, simplifying procedures, and enhancing contamination safeguards, aligning with WHO’s goals to eliminate cervical cancer.
The Pap Smear, named in honor of George Papanicolaou, PhD, and cervical cytology in general opened the door to cervical cancer prevention in the 1940s.1 In the 1970s and 1980s Harald Zur Hausen’s Nobel winning work that established human papillomavirus (HPV) infection as the obligatory cause of cervical cancer.2 This introduced a new screening target that could potentially become a routine laboratory test, not dependent on individual technical skills and reader concentration like cytology.
Screening for human papillomavirus (HPV) has since become the dominant technology for cervical cancer screening in countries with adequate medical resources. First as a co-test with cytology and recently, more adoptions as the primary screening target.3-4 However, many barriers still exist in low- and many middle-income countries where ~90% of the world’s cervical cancer occurs.5
Cervical Cancer Screening: Looking Back
Looking back at the mid-to-late 1990s when HPV testing was entering the world of screening for cervical cancer, the idea of self-collection was born.6 Previously, with the Pap smear, the need for well-preserved cells made vaginal self-collection sub-optimal. However, now with a molecular target, i.e., HPV, preservation of cellular integrity is no longer a concern.
When we first began our investigations in 1997 in rural China, the focus was: “Is self-collection a viable option for cervical cancer screening?” Our first two studies, Shanxi Province Cervical Cancer Screening studies I and II (SPOCCS I and SPOCCS II) used the available signal amplification Hybrid Capture technology.7 In these studies, self-collection was found to be significantly less sensitive to detect clinical endpoints (CIN2+), even with a change from cotton swab to nylon brush collection in SPOCCS II.8-9 In SPOCCS III (2006-2007, 2,625 patients), the study was specifically designed to understand why this difference in sensitivity occurred.10
Physicians collected direct endocervical, upper vaginal, lower vaginal and perineal specimens; and the patients provided self-collected samples. Again, samples were analyzed using Hybrid Capture technology. However, to further understand the differential results, all patients who tested positive in the endocervix and/or self-collection (total 397 patients) had all five of their study samples tested using Linear Array, a PCR based genotyping assay for 37 HPV types from Roche. Of note Gravitt, et.al. had explored the use of Linear Array in 2001 combined with self-collection as a potential tool to conduct longitudinal monitoring of HPV infection.
Linear Array showed similar “analytical” sensitivity of vaginal self-collected specimens to their direct endocervical collected specimens.11 SPOCCS III provided the first clinical endpoint data, and although again demonstrating inferior self-collection results with Hybrid Capture, self-collection was noted to be similar in sensitivity to direct endocervical collection using the PCR-based technology.10 Then, published in 2012, the randomized prospective Shenzhen Cervical Cancer Screening Trial II (SHENCCAST II, 8,556 evaluable patients) definitively demonstrated that using a PCR-based assay technology would allow self-collected samples to be as sensitive for CIN2+ as physician collected endocervical specimens. In addition, SHENCCAST II showed that with a PCR assay the collection device (nylon brush vs flocked swab) made no difference. We believed that this finding could have important cost benefits in the future.12
We studied patients’ acceptance of self-collection13-14 and combined with the above discoveries the initial problem was solved. Self-collection could be an effective component of a cervical cancer screening program, and the timing turned out to be good. New PCR assays were being developed that were applicable to large scale screening efforts as opposed to the more impractical laboratory-based Linear Array which was not designed for that purpose.15-16
The Benefits of Cervical Cancer Self-Collection
Self-collection as a technology is special. In the western world where cervical cancer screening programs are robust and mature, where vaccination programs are approaching 20 years, cervical cancer and its precursor lesions are less common. In these settings more than 50% of cancers occur in women who, for a variety of reasons, do not participate in organized screening.17 Self-collection has proven to be a solution for some of these non-participants and they have now become among the screened.18 In the parts of the world where 90% of cervical cancer occurs, lacking both in human and financial medical resources, self-collection can be the starting line for a sequence of paired adaptive technologies that create a system, and systems solve problems.
Realizing that our task was now to reach the people most in need, we identified several key obstacles:
- We needed a system to organize the self-collection.
- We needed a simple low-cost method for specimen transport and possibly short-term storage.
- We needed to identify simple low-cost PCR technologies that technicians with only basic laboratory skills could perform.
- If the PCR assay was fast, the possibility of a screen and treat program that would reduce “lost-to-follow-up” could be designed.
- The technology needed safeguards to prevent the risk of laboratory contamination, which has always been a concern in all laboratories, regardless of their sophistication.
It is important to recognize that from this point on, efforts to address the hurdles noted above were world-wide.
Addressing a Worldwide Need
Using community based participatory modeling, we first carried out the Peru Cervical Cancer Prevention Study (PERCAPS) in Peru19 and then the Chinese Cervical Cancer Prevention Study (CHICAPS) in China20 to design collection models based on central laboratory processing. Our community-based system was then adapted to an internet model.21
The realization that we could screen entire communities or regions of a country, which resulted in thousands of samples per day, pushed our search for faster laboratory processing. We had used the PCR-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry method (MALDI-TOF) HPV genotyping in SHENCCAST II12 and then collaborating with BGI Shenzhen the first HPV assay that utilized next-gen genomic sequencing was developed (SEQHPV). Perfect for a centralized sophisticated laboratory, it was very fast, and the large volume reduced the cost per test.22
Our initial goal for specimen transport and storage was to eliminate liquid media. We developed kits to try and avoid the potential risks, costs, and complexities of using and transporting alcohol containing liquids. We studied and then developed inexpensive solid media transport cards.23 The cards were very light, easy to transport and store, and the patient could see their sample on the card (positive feedback). The cards were excellent until they reached the laboratories where they were a challenge to process since precise punching was required and safeguards were needed against laboratory contamination.24 Most recently, we explored simple “dry brush” transport by placing the specimen brush in an empty tube which worked well when tested up to two weeks after collection. We felt that this was a good simulation for remote transport and the cost of a simple brush and small tube could be a few pennies.25
The World Health Organization’s (WHO) global strategy for the elimination of cervical cancer was endorsed by the members in 2020. The WHO goals No. 2 and No. 3 for 2030 state: 70% of women are screened with a high-performance test by 35 and 45 years of age; and 90% of women identified with cervical precancer or cancer receive treatment and care.26 Self-collection provides a powerful tool to reach the screening goal. However, it is well documented that providing rapid results so patients are not lost to follow-up increases the likelihood 90% will be treated. The unfortunate reality is that screening is useless, unless those who test positive receive appropriate follow-up care.27-28
Breaking the Barriers to Cervical Cancer Screening
The barriers are significant when the desire is to bring fast, accurate, low cost, safe technology to areas of the world with limited resources. Thousands of providers will need to receive the self-collected samples that can be rapidly processed at low cost. If it were then possible to provide all the caregivers with a simple risk-based diagnostic algorithm and easily transportable treatment technologies the 90% target will come into view.We became aware of a potential candidate several years ago.
Our research team did some validation and transport trials with the AmpFire technology, a fast, low-cost PCR-based assay from Atila Biosystems, which reported HPV genotypes: 16, 18/45, and 12 type pool.25,29 In 2022, a collaboration between the NIH and Atila Biosystems was published that re-designed AmpFire to ScreenFire RS. The ScreenFire assay reports positive results in four cancer risk-based channels, based on HPV genotyping. The goal is to provide guidance for clinical care, and improve resource management for the low resource regions of the world.30-31
ScreenFire RS was then incorporated into the NIH trial “HPV-Automated Visual Evaluation” (PAVE) designed to evaluate the integration of self-collection and testing for HPV, deep-learning-based automated visual evaluation (AVE), and targeted therapies. Phase I has involved screening more than 44,000 women in nine countries. An evaluation of the full model’s effectiveness (Phase II) is ongoing.32
Atila Biosystems has now added the Zebra Biodome technology to the ScreenFire RS assay, which incorporates all prior benefits, especially the simplicity of using raw samples thereby eliminating the need for DNA extraction.33 The Zebra Biodome technology prevents the risk of laboratory contamination, a breakthrough innovation for all laboratory settings especially those in low resource regions.
As pictured in Figure 1, the Zebra BioDome is designed to simplify lab procedures by providing all the amplification reagents within the reaction wells, to minimize lab technician error and the risk of carryover contamination in PCR assays. These 0.1mL BioDome strips or plates are configured to contain a proprietary chemical material within the strip tubes to prevent PCR amplicons from leaking into the environment. After injecting the sample into a tube, when heated, the reagents combine with the sample and the proprietary sealant rises to seal the tube.33 The ScreenFire Zebra Biodome HPV technology has now been implemented by the PAVE sites. This type of critical technology promises to be an important component for the concluding chapters of the self-collection story that will lead to the treatment systems needed for self-collection to reach its maximum potential.
ABOUT THE AUTHOR
Jerome L Belinson, MD, is the former chairman of the Department of Obstetrics and Gynecology at the Cleveland Clinic Foundation (1990-2000) and still holds a professorship with the Cleveland Clinic Lerner College of Medicine. He is the founder of Preventive Oncology International Inc. (POI) and has personally worked for more than 25 years in multiple provinces throughout rural China as well as Mexico, Peru, and the Dominican Republic; in addition to many other international collaborations. He was trained in Ob/Gyn at Columbia University’s Presbyterian Hospital in New York City, and in gynecologic oncology at the University of Miami, Jackson Memorial Hospital. Belinson currently serves as medical advisor to Frantz Viral Therapeutics and Atila Biosystems.
Featured Photo: Christian Weiß | Dreamstime.com
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