Ovarian cancer has many sub-types. Epithelial ovarian cancer is the most common. Nine in ten women and people diagnosed with ovarian cancer have this type. Epithelial ovarian cancer is also the 7th most commonly diagnosed cancer among women in the world. Yet, we still don’t have a national screening programme for ovarian cancer. Kacper, a PhD student funded by Eve’s Fellowship of Dr Neil Ryan at the University of Edinburgh blogs about why we currently have no screening programme for ovarian cancer and what research is being done in this area.

Epithelial ovarian cancer has the poorest outcomes of the five gynaecological cancers. Patients rarely show symptoms in the early stages, and many of those who do experience symptoms often report issues that are not specific to cancer and can be explained by other conditions like irritable bowel syndrome (IBS).  By the time most cases are diagnosed, the disease has typically advanced to stage three or four, when treatment is more difficult and survival rates drop. Despite decades of research, there is still no effective, widely adopted screening method for early detection. 

The first hurdle lies in the biology of the disease. Epithelial ovarian cancer originates from cells located on the surface of a fallopian tube, but early tumours are small and  don’t usually produce obvious signs that can be detected through routine exams. 

One of the most well-known biomarkers for ovarian cancer is CA-125, a protein often raised in women with the disease. But CA-125 is far from perfect. It can be raised for a number of non-cancerous reasons, including menstruation (periods), endometriosis, and even pregnancy. It also fails to rise in some women with early-stage ovarian cancer. In short, CA-125 lacks both specificity and sensitivity, making it unreliable for population-wide screening, especially in post-menopausal women. 

HE4 (human epididymis protein 4) has been studied as a complementary biomarker, and while it improves accuracy slightly when combined with CA-125, the combined method still doesn’t meet the criteria needed for a screening tool in women  without symptoms.  

Ultrasound, (particularly transvaginal ultrasound), is another tool that has been explored for screening. Transvaginal ultrasounds are when a small scanner probe is inserted in the vagina to get a picture of the womb, ovaries and fallopian tubes. While it can detect masses or abnormalities, it cannot reliably distinguish between benign and malignant tumours (cancer vs non-cancer). This leads to a high rate of false positives, which can result in unnecessary surgeries, anxiety, and increased healthcare costs. 

Several large-scale studies, including the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS, which was supported by The Eve Appeal), have tested combinations of CA-125 and ultrasound in screening strategies. While these trials showed that it is possible to detect cancer earlier, they didn’t ultimately reduce mortality. In other words, finding the cancer earlier didn’t necessarily mean women lived longer. The trials also showed a high number of false positives and no clear survival benefit, failing to justify routine screening in the general population. 

Due to these challenges, medical organisations are hesitant to recommend routine screening for ovarian cancer in  women without symptoms who are at an average risk. Instead, efforts are focused on identifying high-risk individuals, such as those with BRCA gene mutations or a strong family history of ovarian cancer, who may benefit from closer monitoring or risk-reducing strategies like  surgery. 

Research is ongoing. Scientists are exploring liquid biopsies (which analyse DNA shed by tumours into the blood), new protein and genetic biomarkers, and machine learning tools to interpret complex data. While promising, these methods are still experimental and require further validation. 

Despite the challenges ovarian cancer presents, there is growing hope on the horizon, especially when it comes to early detection. The spotlight on high-grade serous epithelial ovarian cancer, the most common and aggressive subtype, has spurred intense research and awareness. Scientists and clinicians are working to identify early molecular and genetic markers, leading to real progress in developing more accurate screening tools. With this increased attention, we’re not just understanding the disease better, we’re also getting closer to catching it earlier, when it’s most treatable.