Why ovarian cancer still takes too long to diagnose, and why that has to change
Every year, thousands of women are told they have a suspicious ovarian mass. It's a sentence that changes everything in an instant, and for most of them, the only way to find out what it actually means is surgery.
It's the part after that people are often surprised to learn. A large proportion of women who undergo surgery for a suspicious ovarian mass turn out not to have cancer at all [1]. The mass was benign. The surgery, with all its risks, recovery time and emotional weight, wasn't medically necessary.
What the science says about current testing
The main blood test used today, CA-125, has been in clinical use since the early 1980s. It measures a protein shed by ovarian cancer cells, and it has real value in monitoring patients who are already being treated for the disease. But as a way to detect ovarian cancer early, its limitations are well documented in the clinical literature [2].
Studies have found CA-125 is elevated in only around 23 to 50% of women with stage 1 ovarian cancer, compared with 80 to 92% of women with advanced-stage disease [2]. In other words, the test performs reasonably well once cancer has already progressed, but is far less reliable at the early stage when treatment options are best and outcomes are strongest.
CA-125 is also not specific to cancer. Levels can rise due to menstruation, pregnancy, endometriosis and other benign conditions of the pelvis, which is part of why the test alone has a low positive predictive value [2]. Combining it with ultrasound and tools like the Risk of Malignancy Index improves things, but the fundamental challenge remains: separating a benign mass from a cancerous one reliably, before a woman goes into surgery, is still an unsolved problem for a meaningful proportion of cases.
Why the stakes are so high
Stage at diagnosis is everything in ovarian cancer outcomes. Data compiled by the American Cancer Society shows women diagnosed at stage 1, when cancer is confined to the ovaries, have a five-year survival rate of around 90% [3]. By stage 4, once the disease has spread beyond the abdomen, that figure falls to somewhere between 17 and 30%, depending on the specific type [3]. Yet the majority of ovarian cancers are still diagnosed after the disease has already spread beyond the ovaries. Better tools for distinguishing benign from malignant masses earlier don't just reduce unnecessary surgery, they sit directly upstream of survival itself.
A wider pattern in women's health
Across many conditions, women wait an average of four years longer than men to receive an accurate diagnosis [4]. Some of the risk factors specific to ovarian cancer are still under-recognised too. A 2024 study published in JAMA, led by researchers at the University of Utah's Huntsman Cancer Institute, followed close to 79,000 women with endometriosis and found that those with more severe subtypes, such as deep infiltrating endometriosis or ovarian endometriomas, had close to 10 times the risk of developing ovarian cancer compared with women without the condition [5]. It's a connection that isn't yet widely understood outside specialist care.
By 2050, an estimated 8 million lives are projected to be at risk from ovarian cancer globally without meaningfully better early detection [6]. That number isn't inevitable. It reflects where the science currently stands, not where it has to stay.
Where the research is heading
Part of what makes ovarian cancer hard to detect with a single protein marker is that proteins in the body rarely tell the whole story on their own. More than half of all proteins in human blood carry glycans, sugar structures attached to the protein after it's built, and changes to these glycan structures have been linked to a growing list of cancers in the research literature [7]. This field, known as glycoproteomics, has been an active area of biomarker research for over a decade, driven by the idea that looking at both a protein and how it's been modified gives a fuller picture than looking at protein levels alone [7].
Combining glycoprotein biomarkers further increases the diagnostic performance, as shown in our discovery research. We're still early in that work, and there's more validation ahead before we can talk about specific results. But we believe this broader approach to the underlying science is where meaningful progress in early detection is most likely to come from.
Why this matters to us
This is the gap we started Proseek Bio to help close. We believe women deserve diagnostic tools that match the seriousness of what they're facing: clear answers, delivered with less waiting and less unnecessary risk. Our work is grounded in the belief that better science, applied with care, can spare thousands of women from surgery they don't need, while making sure the women who do need urgent care get it faster.
If this is a space you care about too, whether you're in healthcare, research, or simply someone who's watched a friend or family member go through this, we'd love for you to follow along as we build.
Sources
Glanc P et al. "First International Consensus Report on Adnexal Masses: Management Recommendations." J Ultrasound Med. 2017;36:849-63. Estimates roughly 1 in 10 women who undergo surgery for a pelvic mass are found to have ovarian cancer.
Al-Musalhi, K. et al., "Validity of Cancer Antigen-125 (CA-125) and Risk of Malignancy Index (RMI) in the Diagnosis of Ovarian Cancer," Oman Medical Journal, 30(6), 428-434, 2015
American Cancer Society, ovarian cancer survival rates by stage
World Economic Forum, on diagnostic delays for women across conditions
Barnard, M.E. et al., "Endometriosis Typology and Ovarian Cancer Risk," JAMA, 332(6), 482-489, 2024
World Ovarian Cancer Coalition, global ovarian cancer projections to 2050
Kim, E.H. & Misek, D.E., "Glycoproteomics-Based Identification of Cancer Biomarkers," International Journal of Proteomics, 2011
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