When Janna Rigby first felt a lump against her back, she thought she had lain down on something while stretching at the gym. But when she stood up, the feeling disappeared. A week later, she felt the same lump when leaning against the kitchen counter, and this time, her husband also felt the lump when he pressed against the spot. Worried, the two rushed to urgent care.

Two months later, after a battery of tests, Rigby learned that she had ovarian cancer – a disease she knew nothing about. The recently retired high school English and drama teacher had been much more worried about getting regular mammograms because her aunt had breast cancer. After learning more about ovarian cancer, she realized that her risk for the disease had been quite high, due to her age, an earlier diagnosis of endometriosis, and the fact that she’d never had children. “I’m a classic candidate. All those things, for lack of a better term, work against you,” Rigby said. Though doctors had aways reminder her to get regular mammograms, she said, “I was surprised that no one said, ‘You might want to think about ovarian cancer’.”

Now three years past her last round of chemotherapy treatment, Rigby regularly speaks to nurses in training to help them understand what their patients will go through. She advocates for ovarian cancer research as a member of the Bay Area chapter of the Teal Run, a nonprofit that raises money for ovarian cancer research and provides support services for people who are diagnosed with the disease. She and other advocates for ovarian cancer patients hope for a screening test that could detect the disease early, while it is easier to treat.

Laura Sanchez, a chemist at the University of California, Santa Cruz, is working to fill this void by developing a screening test for ovarian cancer that uses pap smear and tampon samples.

Despite systemic barriers to studying gynecological health conditions, this long-awaited screening test is important for the health of approximately 50% of the population — everyone who has ovaries. Ovarian cancer occurs at a similar rate in all racial and ethnic groups, with over 238,000 people in the US alone living with ovarian cancer in 2021. The National Institute of Health estimates that 19,680 people were diagnosed with ovarian cancer in 2024, and 12,740 people died from the disease that year.

“That’s the holy grail, to catch it early and then prevent it getting to the basically untreatable stage,” said Sanchez.

When caught before the cancer spreads (stage 1), ovarian cancer has a 92% five-year survival rate. This means that 92% of people diagnosed with ovarian cancer will still be alive five years after their diagnosis. However, it is usually caught after it has spread to other parts of the body (stage 3 or 4), at which point patients have a 31% five-year survival rate. “That’s the holy grail, to catch it early and then prevent it getting to the basically untreatable stage,” said Sanchez.

If successful, an ovarian cancer screening test could be offered to those at risk, ideally alongside other screening tests such as mammograms and pap smears. When caught and treated at an earlier stage, the disease is more survivable.

Why is ovarian cancer so deadly?

Ovarian cancer is rare — accounting for an estimated 1% of new cancer cases in 2024 — but deadly. Once diagnosed, patients are often told about their chances of survival in terms of the 5-year survival rate, which is the percentage of people who live for five years after they are diagnosed. The average 5-year survival rate for ovarian cancer is 50.9%, which is far lower than the rate for more common cancers like prostate (97.5%), breast (91.2%), or melanoma (94.1%). Even though melanoma is five times more common than ovarian cancer, more people die from the latter each year.

This striking disparity largely comes down to the stage at diagnosis. Cancer stages are a way of measuring how far a cancer has spread throughout a person’s body. At stage 1, the cancer is confined to a single site, such as the ovary. At stage 2, the cancer spreads to nearby lymph nodes, but is still relatively localized. By stage 3 and 4, the cancer metastasizes, or spreads, to other parts of the body. Unlike many other cancers, ovarian cancer often goes undiagnosed until stage 3 or 4. At this stage, even the complete removal of the reproductive system and surrounding lymph nodes leaves some cancer behind. This is similar to other particularly deadly cancers, such as pancreatic cancer, that often go undiagnosed until late stages.

Why is ovarian cancer diagnosed so late?

Janna Rigby considers herself lucky that her cancer was diagnosed in stage 1A. She didn’t have severe warning signs, such as back pain, abnormal vaginal bleeding, or pelvic pain or pressure. The signs she did have seemed normal to her: “You feel bloated. You will have to go to the bathroom all the time. You might be constipated,” she said. “But it’s the types of things that most women experience almost monthly. So you would not really think anything of it.”

“So things for me went faster, and it was caught at stage one.”

When she went to urgent care after feeling the lump, Rigby’s diagnosis came relatively quickly – after only two months. “I felt so lucky and so blessed that the things just fell into place,” she said. “So things for me went faster, and it was caught at stage one.” But that’s not the case for many, she said.

Diagnosing ovarian cancer takes a hefty amount of detective work. According to the Center for Disease Control, many conditions including irritable bowel syndrome, endometriosis, and ovarian cysts all have similar symptoms to ovarian cancer. After ruling out other causes, a transvaginal ultrasound can narrow it down to a gynecological issue rather than problems with another abdominal organ system. After that, invasive surgery is the only clinically accepted method to differentiate these conditions.

Over the last two decades, researchers across the globe identified patterns of proteins, DNA, and RNA that are only found in samples from people with ovarian cancer. Some of these biomarkers are present in blood, while others are found in samples taken from pap smears or even used tampons.

In 2008, there was hope that a simple blood test could replace this arduous process. Investigators at Yale University developed OvaSure, a blood test that the Laboratory Corporation of America sold and marketed as a diagnostic tool specifically for ovarian cancer. Although the test effectively identified six proteins that are known markers for cancer in blood samples, the proteins are not specific to ovarian cancer, meaning they can also be found in people with different cancers as well. That meant the test could falsely indicate that a patient had ovarian cancer, even if they actually had a different form of cancer. As a result, the Food and Drug Administration (FDA) pulled OvaSure from the market after only 4 months.

Gynecologists and oncologists across the world currently rely on invasive methods such as transvaginal ultrasounds and surgeries to diagnose and treat ovarian cancer. These procedures are typically only done for people with very high risk of ovarian cancer, or who already exhibit symptoms. In the UK, a clinical trial investigated if performing transvaginal ultrasounds on people over 50 years old without symptoms would allow doctors to catch ovarian cancer at an earlier stage, similar to mammograms for breast cancer and colonoscopies for colon cancer. They hoped this would detect cases when they were more treatable and therefore decrease the death rate from the disease. While these invasive early screenings decreased the death rate by about 10%, there were also a large number of false positives, or instances when the test falsely indicated that a person had cancer. According to Usha Menon, a professor at University College London and head of the trial, this change was not large enough to recommend that people at average risk be screened using these methods.

Sanchez is now taking advantage of decades’ worth of work from researchers around the globe developing technology that can identify not just DNA, but small proteins in biological fluid. Over the last five years, Sanchez’s lab used this technology, called MALDI-TOF mass spectrometry, to identify the specific collection of small protein biomarkers – also known as a “fingerprint” – in vaginal fluid that indicate the presence of ovarian cancer. This fingerprint method is already used in hospitals and veterinary laboratories to identify bacterial infections. Sanchez wants to make it easier to collect samples – using tampons.

Why Tampons?

A Papanicolaou smear, or pap test, is a common part of a routine gynecological exam where the gynecologist uses a swab to take a sample of cells from the cervix, the entrance to the uterus that connects to the vagina. These cells are examined under a microscope to see if they may be cervical cancer. Many ovarian cancer researchers such as Amy Skubitz, a professor at the University of Minnesota, are developing ovarian cancer screening tests that use pap smear samples instead of blood samples, because they are closer to the disease site and often contain additional biomolecules not found in blood.

Anatomical diagram showing how fluid moves from the ovaries to a tampon in the vaginal canal. Image Credit: Cat Smith

But collecting gynecological samples is a difficult problem for ovarian cancer researchers. That’s because pap smear samples are destroyed after they are checked for cervical cancer, unless the person getting the exam consents to have the samples stored for a specific research project or clinical trial. Storing these samples requires a lot of space within specialized freezers, so it can be costly for individual researchers to store enough samples for their experiments.

To centralize this process and save resources, large organizations such as the National Cancer Institute at the National Institutes of Health often set up biorepositories, sometimes called biobanks. These facilities collect and store samples, such as blood and ovarian cancer tissue, from patients around the country who agreed to donate the tissue. Then, researchers can request to test their method on these samples to see if it works.

However, pap test samples are not stored by biorepositories, so individual researchers or universities with associated medical centers must collect and store their own pap samples for specific projects.

Sanchez wanted to see if the small protein biomarker fingerprint her group found could be detected in mouse pap test samples before trying to test it in difficult-to-obtain human pap test samples. Sanchez sent one of her graduate researchers, Melissa Galey, to a lab run by Joanna Burdette, an ovarian cancer researcher at the University of Illinois at Chicago. There, Galey conducted the mouse equivalent of a pap smear – pipetting saline into and out of the mouse’s vagina – on healthy mice and those with transplanted human ovarian cancer. Back in Sanchez’s lab in Santa Cruz, Galey ran the samples through MALDI-TOF mass spectrometry – and found that the ovarian cancer fingerprint only showed up on samples from the diseased mice. This meant they could tell which mice had ovarian cancer just by looking at the fingerprint.

Now that she knew the potential ovarian cancer screening test worked on mice, Sanchez needed human samples to make sure the test would work in a clinical setting. However, the lack of biorepository samples led her to consider a different way of gathering samples from human patients: collecting used tampons.

“Tampons are pretty smart, because you are collecting this kind of biological fluid that is produced every single month and just thrown away,” said Sanchez.

Tampons, the 1- to 2-inch-long rayon and cotton tubes that many people insert into their vaginas to contain their menstrual flow, each store about a teaspoon of liquid, including cells and biomarkers that are shed from the cervix – similar to what would be collected from a pap smear. “Tampons are pretty smart, because you are collecting this kind of biological fluid that is produced every single month and just thrown away,” said Sanchez.

While typically only used during menstruation, tampons can be inserted at any time of the month and will absorb whatever fluid is present. This makes them ideal for collecting samples from the reproductive system in a self-administered and less invasive way than a pap smear.

After hearing a talk about Sanchez’s project, cancer biologist Anthony Godwin at Kansas University’s Cancer Center realized he could help. He had tampons left over from another study and realized they could be useful for other ovarian cancer researchers. After talking with Sanchez about the project, he sent some of the tampons to her lab.

With the tampons Godwin provided in the freezer, Sanchez and her colleagues needed to find a way to extract the liquid stored in the absorbent material. She tasked a graduate student in her lab, Gordon Luu, with solving that problem. “I bought Gordon a box of tampons, and I told him to have a field day,” said Sanchez. “We wanted to make sure that we did our due diligence before we opened up the patient samples.”

After a lot of trial and error, the method they settled on was remarkably simple. They cut off just one centimeter from the tip of the tampon, and cut that section in half. This small piece of frozen fluid-filled cotton was thawed in a syringe filled with saline solution. Then, a few pumps of the syringe released the biomolecules out of the tampon and into the liquid. After evaporating off the water, the remaining powder went on to MALDI-TOF mass spectrometry for fingerprint identification.

The screening test worked well on the 54 tampons Godwin provided – it correctly identified the samples from the eight people who were diagnosed with ovarian cancer. While individual markers varied between samples – even from the same patient – the fingerprint method proved reliable in this study. Sanchez often wonders, “Why hasn’t anyone done this before? I still don’t have a good answer other than I just think people are kind of grossed out by it,” said Sanchez.

The path to the clinic

If a screening test like Sanchez’s gets FDA approval, doctors could add “tampon sample” as just another thing to collect alongside urine and blood samples during annual exams. Gynecologists could collect a second swab to screen for ovarian cancer during a regular gynecological exam, or just ask a patient to put in a tampon the night before and leave it at the doctor’s office along with their urine sample.

However, a lot stands between this burgeoning technology and a widespread screening test. First, Sanchez will need to test her method on samples from thousands of patients in a small-scale study. Then will come the clinical trials, culminating with a large-scale study like the one Menon conducted to test transvaginal ultrasounds. These studies use death rates from ovarian cancer as the main way to see if screenings are effective, so they necessarily take decades to run. Only then might regulatory agencies and gynecologists adopt a new screening test like Sanchez’s.

This long path to approval is part of why some researchers like the idea of using multiple biomarkers. They want to maximize the chances of at least one viable screening test making it through the entire validation and approval process. “I don’t know whether it’s going to be a combination of the proteins that I discover, or Laura Sanchez discovers, or a bunch of them together,” said Amy Skubitz, a professor at the University of Minnesota. She and other researchers know that a wide range of biomarkers are “going to be on that swab, [so we] look for abnormalities there.”

Many other researchers are developing screening tests of their own. Other early-stage research like Sanchez’s focuses on extracellular vesicles, microRNA, and other biomarkers that similarly could not be reliably detected until recent years. Some groups are looking at markers in patient blood, like OvaSure did, though with much higher scrutiny to ensure the markers are specific to ovarian cancer to prevent false positives. Recently, researchers ran small clinical trials to test pap smear samples for DNA biomarkers for ovarian cancer. These more recent blood and pap smear approaches await validation in large scale clinical trials to make sure they work well enough to use with people at risk of ovarian cancer.

The search for samples

While researchers and clinicians are closer to a screening test for ovarian cancer than ever before, more work needs to be done. Partially due to the history of too-early adoption of OvaSure, ovarian cancer research is highly scrutinized to prevent similar incidents. “That’s why we have a really high bar,” Sanchez said, because in the past, it has “very famously gone wrong”.

To make sure her test doesn’t follow the path of OvaSure, Sanchez is searching for thousands of samples – enough to demonstrate that the method works well enough for a dedicated clinical trial. Biorepositories that store pap smear and tampon samples are virtually nonexistent. This means Sanchez’s best source of such samples in the U.S. is from individual researchers such as Godwin. Sanchez also hopes to partner with clinicians at nearby institutions to collect samples for her research.

In the end, Sanchez hopes that her test could alert patients that something is wrong and they need to go in for diagnostic testing. “I think any indication that you need to go back for further testing gives the patient more agency and more information,” she said.

That mission gives Janna Rigby and other patients and their loved ones hope. When she heard Sanchez speak about this work at a public talk, Rigby was moved by the possibility of others not having to go through the as much of the ordeal she experienced. She went up to talk to Sanchez and recalls her saying, “I want my team to know that we do this job for people like you that are out there.”

© 2025 Rita Aksenfeld / UC Santa Cruz Science Communication Program