Cervical cancer is the fourth most common cancer in women globally, according to the World Health Organization. Even with vaccination, routine screening is a crucial step to prevention.

A conventional screening method is the pap smear test, uncomfortable though it often is: the speculum, a cold, duckbill-shaped metal instrument, is inserted into the vagina, widening the walls for a sample of cells from the cervix to be collected with a long, narrow brush.

Alternatives to this much-dreaded test have been invented, such as self-swabbing kits and urine tests. Recent years have also seen the development of using menstrual blood to detect human papillomavirus infection. A local femtech innovation start-up, WomenX Biotech, achieved a breakthrough in women's health diagnostics as the first in Hong Kong to launch a highly accurate, specific, and accessible sanitary pad for HPV detection, PadX-HPV.

When testing 24 common HPV strains, the pads achieved 99.2 percent accuracy and 100 percent specificity among 119 participants, making it the world's most accurate non-invasive HPV test. With the success, WomenX teamed up with Pangenia, a leading molecular diagnostic laboratory that specializes in menstrual blood-based diagnostics.

WomenX was founded by biochemist Choi Pui-wah in 2019, who boasts an extensive academic background as a postdoctoral fellow at Harvard Medical School and a lecturer at The Chinese University and Saint Francis University.

According to her, "WomenX's sanitary pads for HPV detection are designed to prevent the growth of microbes, which could increase to 6,000 times in four hours. The menstrual blood is locked in the bottom layer of the pad, keeping the surface dry and sterile for hygienic reasons and for later diagnostics."

The pad is used on heavy flow days. When half of it is soaked, it can be removed, sealed in a bag provided and sent to the laboratory within 25 days. Results are available within three business days upon receipt of the pad.

"It's an intricate process to collect the cervical cells while facilitating the downstream detection of HPV. From packing the pad to disassembling it to extracting DNA to applying screening technologies, the entire procedure requires a 30-day preservation period," says Choi. "Normal sanitary pads cannot maintain such a high degree of effectiveness."

A range of materials was tested to capture and detect the cervical cells in the early stage of the research, before Choi and her team came up with the optimal design.

She credits the accuracy of the pads to their very own production line located in Hong Kong, enabling modifications if necessary, easily.

The service does not end when patients get back the test results, as the package includes a consent form regarding enrollment in a clinical study.

In the case of HPV positives, thorough follow-up care is available.

"Upon entering the study, the patient will receive free pap smear tests, and we will test whether their cervical cells have mutated. If they have, we will refer patients to a doctor," says Choi, who also provides information resources on HPV.

Choi insists WomenX is committed to long-term support for patients throughout treatment.

"Cervical cancer patients have to go through critical chemotherapy and radiotherapy for nearly three months, which is an extremely difficult process. We offer support through our network of nonprofit cancer organizations that offer therapy and support groups."

Furthermore, the pad can be used to monitor the HPV infection after the initial positive result. "Patients with HPV infection are usually recommended to get a pap smear every six months. With our sanitary pads, they no longer have to go to a physician. They can monitor it in the comfort of their home," says Choi.

Pangenia has been studying sanitary pads for HPV detection for over a decade. "In the past, it was hard to keep the concentration of the cells using normal pads," says founder Joseph Tam Wing-on, an esteemed scientist with over 40 years of teaching and research experience in the biochemical field.

"Combining our past experience and WomenX's distinct development, our sanitary pads are more effective in detecting HPV than urine tests and at-home cervical swab kits," Tam says. Data from their clinical research shows that commercial urine tests for HPV detection and self-sampling kits only reach 80.7 percent and 84.4 percent of accuracy, respectively - a far cry from WomenX's 99.2 percent.

Tam stresses the importance of conducting regular HPV tests. "What people need to remember is that cervical cancer can be prevented through screening, diagnosis, and vaccination - they complement each other."

It is concerning that the screening rate for cervical cancer in the city is fairly low, with only 21.1 percent of women aged between 25 and 64 registered with the administration's Cervical Screening Information System, according to the Department of Health's annual statistics report in 2023.

WomenX's own clinical data center reveals that only around 30 percent of women in Hong Kong have done a pap smear test before.

In China, where cervical cancer screening tests such as pap smears are free, the screening rate was 36.8 percent for women aged between 35 and 64 years from 2018 to 2019.

Choi points out that while the screening rate for cervical cancer in Hong Kong has changed very little, the incidence rate of cancer is ever-increasing - a 10 percent jump from the last decade.

"You have to fill in the gap to make the screening rate high. Then the cancer rate can be lowered," she says. "The need for biotech and femtech stems from this gap. If we want to eradicate cervical cancer, the screening rate may need to be as high as 80 percent."

In addition to their high accuracy and non-invasive nature, WomenX's pads can be instrumental in removing barriers to screening.

"When we were recruiting participants for clinical trials, there were a lot of physical and emotional barriers, such as embarrassment about taking invasive tests," says Choi. "This is particularly true in the case of domestic workers, as they often don't have the time to arrange appointments for screening."

Due to its affordability and simple instructions, WomenX's pads eliminate the need for a physician during screening, benefiting women in low-income countries. "The screening rate in southeast Asian countries is low, too. We also have to consider regions with inadequate medical facilities," says Choi. "That's why we plan to enter their markets in the next stage."

Noting that non-invasive medical procedures are the trend, Tam hopes that "with the discomfort removed and the advent of such an accurate alternative, more women would be encouraged to undergo cervical cancer screening regularly."

Choi observed the lack of research on menstrual blood when she started studying this alternate screening approach in 2019. "Not many people were studying menstrual blood at the time. There were at most 10 research papers on it. I had so many questions, prompting me to initiate the process from scratch." Over the past few years, the biochemist had collected a liter of her own menstrual blood for research and tests.

"I think it is very worthwhile. My hope is that there will be more research on menstrual blood and sanitary pads to support women's health care," says Choi.

(Greta Ng)

Goodbye to pap smears and hello to sanitary pads