Ovarian cancer is usually found late. It causes few clear symptoms early on, and there is still no screening test that saves lives in women at average risk. On 10 November 2026, researchers at Hoag Family Cancer Institute in California published a study in Nature Medicine describing an ovarian cancer blood test that picks up a small RNA molecule, called Tu-stroma, already present at the precancerous stage.
The results are striking, but this is early research: the test is not available from any laboratory and has not been approved for medical use. Here is what the study actually showed, what it does not show yet, and what you can do today.
Why ovarian cancer is so hard to catch early
The U.S. Preventive Services Task Force, the American expert panel on screening, recommends against screening women without symptoms who are not known to carry a high-risk inherited mutation (grade D). The US National Cancer Institute explains why: in large trials, combining the CA-125 blood test with transvaginal ultrasound did not reduce deaths from ovarian cancer, and false-positive results led some women to unnecessary surgery. For a full overview of the disease, see our guide to ovarian cancer symptoms and testing.
The CA-125 blood test has two weaknesses. It often stays normal at the very beginning of the disease, and it can rise for many harmless reasons, such as an ovarian cyst, fibroids, endometriosis or a period.
What the Nature Medicine study measured
Researchers now know that the most common and deadliest type, high-grade serous carcinoma, usually starts at the far end of the fallopian tube rather than in the ovary itself. Before it becomes invasive, it goes through a precancerous stage called STIC (serous tubal intraepithelial carcinoma). Until now, STIC could only be seen under a microscope, on a tube removed during surgery.
The team measured Tu-stroma RNA inside extracellular vesicles, tiny bubbles that cells release into the blood. They analysed stored serum samples from 506 people:
| Group studied | Number of people |
|---|---|
| Normal tubes and ovaries on pathology | 143 |
| Benign ovarian or tubal lesion | 88 |
| Isolated precancerous lesion (STIC) | 43 |
| High-grade serous cancer, stages I to IV | 232 |
The results: a signal already present at the precancer stage
According to the paper's abstract, Tu-stroma levels were higher in STIC and in cancer than in normal or benign cases, including in premenopausal women. For telling STIC apart from normal tissue, the marker clearly outperformed CA-125, which did little better than chance at this stage. According to Hoag's announcement, reported by several specialist outlets, the test detected the precancerous lesion in about 92% of affected women in a validation group and correctly classified about 98% of healthy women.
Another encouraging point: the marker did not rise systematically with inflammation, normal physiological conditions or other cancers. Its level also changed little with cancer stage, which suggests it reflects early tumour biology rather than tumour size.
What this study cannot tell us yet
- The samples were tested after the fact, in women whose diagnosis was already known. A prospective study, following women in real life, is the next step.
- The very high scores need to be confirmed independently by other teams.
- In a low-risk population, even an excellent test produces false alarms: how much a positive result means depends heavily on a woman's starting risk.
- Today, a negative result cannot rule out a lesion or justify delaying recommended preventive surgery.
What it means for you today
For now, nothing changes in your care. This test cannot be ordered, and routine ovarian cancer screening is still not recommended for women at average risk. Women who carry a BRCA1 or BRCA2 mutation would probably benefit first: they often face a decision about removing their tubes and ovaries to prevent cancer, which brings on early menopause. If several relatives have had breast or ovarian cancer, ask your GP about genetic counselling and testing.
Which tests can monitor or screen for this?
- CA-125, requested when there are symptoms or a mass on ultrasound, to guide diagnosis and monitor treatment, never on its own for screening. See also our guide to tumour markers.
- Pelvic and transvaginal ultrasound, to describe an ovarian mass.
- BRCA1/BRCA2 genetic testing, after genetic counselling, when there is a strong family history.
- Routine blood tests (full blood count, kidney and liver function tests) requested by your doctor before surgery or treatment.
Recent research advances
Ovarian cancer research has changed direction in recent years. Because most aggressive cancers start in the fallopian tube, removing the tubes during another planned pelvic operation, once a woman no longer wants to become pregnant, has become a prevention strategy. The European Society of Gynaecological Oncology backed it in a 2026 consensus published in JAMA, and a large Canadian study found fewer ovarian cancers in women who had the procedure. At the same time, researchers are testing new blood markers and repeated measurements over time, since a single marker is not enough. Multi-cancer blood tests are part of the same effort, as explained in our article on the multi-cancer early detection test. The Tu-stroma study fits this shift: the goal is no longer only to find a small cancer, but to spot the lesion before it becomes cancer.
When to see a doctor
See your GP or gynaecologist if you have bloating, pelvic or tummy pain, difficulty eating or feeling full quickly, or needing to wee more urgently or more often, that is new and keeps coming back, or any unusual bleeding, especially after the menopause. Mention any family history of breast or ovarian cancer. Call 999 for sudden, severe abdominal pain.
Glossary
- STIC: serous tubal intraepithelial carcinoma, a precancerous lesion of the fallopian tube that can lead to high-grade serous cancer.
- High-grade serous carcinoma: the most common and most aggressive type of ovarian cancer.
- Non-coding RNA: a molecule made by cells that does not produce a protein but helps control how the cell works.
- Extracellular vesicles: tiny bubbles released by cells into the blood that carry pieces of their contents.
- CA-125: a protein measured in blood, used to monitor some ovarian cancers but not specific.
- Prospective study: a study that follows people forward in time, before the disease is known.
Frequently asked questions
Is there a blood test for ovarian cancer?
Not one that works for screening yet. CA-125 is not a screening test. The Tu-stroma test is promising but remains a research tool that must be validated in prospective studies.
Does a normal CA-125 rule out ovarian cancer?
No. CA-125 can be normal early in the disease and high for benign reasons. It is always interpreted alongside symptoms and imaging.
Can I ask my laboratory for the Tu-stroma test?
No. It is not commercially available and has not been authorised for medical use.
Who would benefit most from this future test?
Women at high risk first, especially carriers of a BRCA1 or BRCA2 mutation, for whom better monitoring could help with the timing of preventive surgery.
How can I lower my risk of ovarian cancer?
With a genetic risk, preventive surgery may be offered. For other women, removing the fallopian tubes can be discussed during a planned gynaecological operation if no future pregnancy is wanted.
Sources
- Wilhelm J, Kumar A, et al. Blood-based RNA biomarker for the early detection of ovarian cancer. Nature Medicine. 2026. DOI: 10.1038/s41591-026-04732-9
- Medical Xpress. Blood RNA signal may reveal ovarian cancer precursors before invasive disease develops. 10 November 2026
- Clinical Lab Products. Blood RNA marker detects precancerous ovarian lesions, Hoag study. November 2026
- U.S. Preventive Services Task Force. Ovarian cancer: screening
- National Cancer Institute. Ovarian, fallopian tube, and primary peritoneal cancer screening (PDQ)
- Piek JM, et al. Opportunistic salpingectomy for prevention of tubo-ovarian carcinoma: the ESGO consensus statements. JAMA. 2026. DOI: 10.1001/jama.2025.24510
- Bahrami F, et al. Effectiveness of opportunistic bilateral salpingectomy in preventing epithelial ovarian cancer: a population-based study. J Natl Cancer Inst. 2026. DOI: 10.1093/jnci/djag251
- Sideris M, Menon U, Manchanda R. Screening and prevention of ovarian cancer. Med J Aust. 2024. DOI: 10.5694/mja2.52227
- Webb PM, Jordan SJ. Global epidemiology of epithelial ovarian cancer. Nat Rev Clin Oncol. 2024. DOI: 10.1038/s41571-024-00881-3
- Stewart KT, Hoang L, Kwon JS. Serous tubal intraepithelial carcinoma (STIC) outcomes in an average risk population. Gynecol Oncol Rep. 2024. DOI: 10.1016/j.gore.2024.101334
Further reading
- Ovarian cancer symptoms and how to get tested
- CA-125 blood test: what your results mean
- Tumour markers: meaning, uses and limits
- Multi-cancer early detection test: 2026 update
- Ovarian cyst size, causes, symptoms and risks
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