Challenges In Screening For Ovarian Cancer: Why There Is No Reliable Early Detection Test Yet

Ovarian cancer remains one of the deadliest cancers affecting women worldwide, largely because it is often diagnosed at an advanced stage. Despite major advances in cancer diagnostics, there is still no universally reliable screening test capable of detecting ovarian cancer early in the general population. On World Ovarian Cancer Day 2026, oncologists and diagnostic experts say the challenge lies not in a lack of scientific effort, but in the biological complexity of the disease itself.

Unlike cervical cancer, which can be detected through Pap smears, or breast cancer, where mammography has become a standard screening tool, ovarian cancer frequently develops silently. Symptoms are often vague, non-specific and easy to dismiss until the disease has already spread. Scientists have spent decades studying blood biomarkers, imaging techniques, genomic testing and artificial intelligence-driven diagnostics, yet no screening strategy has consistently demonstrated enough accuracy to be recommended for widespread population screening.

Experts say the difficulty reflects a broader challenge in cancer medicine: detecting tiny, early-stage biological changes without triggering false alarms that can lead to unnecessary surgeries, anxiety and overtreatment.

Why Ovarian Cancer Is Difficult To Detect Early

According to the World Health Organization (WHO), ovarian cancer is often diagnosed late because symptoms such as bloating, abdominal discomfort, urinary urgency and fatigue are subtle and overlap with common non-cancerous conditions. Doctors say this "silent" nature makes ovarian cancer particularly difficult to screen for in asymptomatic women.

Dr Ankur Bahl, Principal Director, Medical Oncology, Fortis Memorial Research Institute, Gurugram, explained that cancer itself is not a single disease. "One of the fundamental hurdles in oncology is that 'cancer' is not a single entity, it is a complex spectrum of hundreds of distinct diseases, each with its own biological fingerprint," he said. "Many malignancies, particularly pancreatic, ovarian and certain lung cancers, are notoriously silent in their early stages."

According to the US National Cancer Institute, nearly 70% of ovarian cancer cases are diagnosed only after the disease has spread beyond the ovaries.

Why Current Screening Tests Are Not Reliable Enough

Currently, the two most commonly used tools in ovarian cancer evaluation are the CA-125 blood test and transvaginal ultrasound. However, experts say neither test is accurate enough for routine screening in women without symptoms or high-risk genetic mutations. CA-125 is a protein that may be elevated in ovarian cancer, but it can also rise due to endometriosis, menstruation, pregnancy, liver disease and other benign conditions.

"The holy grail of screening is balancing sensitivity with specificity," Dr Bahl explained. "A test must be sensitive enough to catch cancer at its inception, but specific enough to ignore benign anomalies."

If a screening test is too sensitive, it may produce large numbers of false positives. This can trigger unnecessary scans, biopsies and even surgeries in healthy women. "When a test is overly sensitive, it triggers a cascade of false positives, leading to extreme patient anxiety, invasive biopsies and the risk of overdiagnosis and overtreatment," Dr Bahl said. At the same time, a test that is too specific may miss genuine early cancers entirely.

The Problem Of Tumour Heterogeneity

One major scientific challenge is tumour heterogeneity, the fact that ovarian cancer behaves differently from one patient to another. "Tumour heterogeneity makes a 'one-size-fits-all' approach impossible," Dr Bahl said. "Even within a single cancer type, genetic and molecular variations differ drastically from patient to patient."

Researchers say ovarian cancer includes multiple subtypes with distinct molecular signatures, growth rates and treatment responses. This variability makes it extremely difficult to identify a single biomarker that consistently detects all cases early. The American Cancer Society notes that no current screening test has been proven to reduce ovarian cancer mortality in average-risk women.

Why Biomarkers Alone Are Not Enough

Scientists worldwide are studying biomarkers, measurable biological molecules found in blood, tissue or body fluids, in hopes of identifying ovarian cancer before symptoms appear. However, many proposed biomarkers lack either sensitivity or specificity. A biomarker may appear in healthy individuals or in unrelated diseases, increasing the risk of false positives. Conversely, some early-stage cancers release very low levels of detectable signals, causing false negatives.

Dr Kunal Sharma, Vice President and Head of Integrated Onco-Pathology at Agilus Diagnostics, highlighted that screening challenges extend beyond ovarian cancer alone. "Early-stage disease can be biologically subtle. In the initial phases, abnormal molecular changes may be present in very small quantities, making them difficult to distinguish from normal variation," he explained. He added that balancing affordability, accessibility and diagnostic precision remains another major challenge for large-scale screening programmes.

Can AI And Liquid Biopsies Change The Future?

Experts say emerging technologies may eventually improve ovarian cancer detection. "We are witnessing incredible strides in advanced oncodiagnostics, particularly with liquid biopsies, genomic sequencing and AI-driven digital pathology," Dr Bahl said. Liquid biopsies involve analysing tumour-derived DNA fragments circulating in the bloodstream. Researchers hope these tests could someday identify cancers before tumours become visible on imaging.

Artificial intelligence is also being used to analyse imaging patterns, pathology slides and genomic data for subtle abnormalities humans may miss. However, experts caution that these technologies remain under development and require extensive validation before they can be widely adopted. According to the National Institutes of Health (NIH), several experimental blood-based ovarian cancer detection approaches are currently being studied, but none are yet recommended as population-wide screening tools.

Who Should Currently Undergo Screening?

While routine screening is not advised for average-risk women, doctors say women with strong family histories of ovarian or breast cancer, or BRCA1 and BRCA2 genetic mutations, may require specialised surveillance. The Centers for Disease Control and Prevention (CDC) recommends that women with inherited cancer syndromes discuss genetic counselling and screening options with healthcare providers.

Experts also advise paying attention to persistent symptoms such as bloating, pelvic pain, feeling full quickly and unexplained abdominal swelling. Despite advances in oncology and molecular diagnostics, ovarian cancer remains one of the most difficult cancers to detect early. The absence of a universally reliable screening test reflects the disease's biological complexity, silent progression and the limitations of existing biomarkers and imaging tools.

Experts say the future may lie in combining genomics, liquid biopsies and artificial intelligence to develop more precise and scalable detection strategies. Until then, awareness of symptoms, genetic risk assessment and timely medical evaluation remain the strongest tools available against one of women's deadliest cancers.

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