Ovarian Cancer and the Ovary: What We Know—and What We’re Still Learning

We’ve made extraordinary advances across cancer detection and treatment over the past several decades. Breast, cervical, and colorectal cancers now benefit from routine population screening programs that save thousands of lives each year. Yet, ovarian cancer remains stubbornly difficult to catch early—and survival gains have been frustratingly slow.

Ovarian Cancer Canada has drawn attention to the fact that survival rates for ovarian cancer have not meaningfully improved in decades. In Canada, the five-year net survival rate sits at roughly 44%. Those aren’t numbers we should simply accept as inevitable.

So why is ovarian cancer still so difficult to tackle? Part of the answer lies in complex cancer biology. Part of it is a lack of reliable screening tools. But part of it reflects a much broader gap: science is still uncovering fundamental truths about how the ovary itself actually works.

Why is ovarian cancer so difficult to detect?

There is a misconception worth clearing up immediately:

Pap and HPV tests are used in cervical cancer screening. There is currently no routine population screening program for ovarian cancer in Canada.

That's a major problem because ovarian cancer is generally much more treatable when it's found before it has spread.

There are tools doctors can use when ovarian cancer is suspected, including pelvic examinations, transvaginal ultrasound, and CA125 blood testing. But that's different from having an effective screening test that can reliably identify cancer in people without symptoms.

And ovarian cancer symptoms aren't always obvious.

They can include persistent bloating, abdominal or pelvic pain or pressure, feeling full quickly, urinary urgency or frequency, constipation, back pain, fatigue, and changes to menstrual bleeding.

If you're reading that list and thinking, Well, those symptoms could describe about a dozen other conditions, you've identified part of the problem. They can. Bloating is common. Constipation is common. Pelvic discomfort is common. None of those symptoms automatically means ovarian cancer.

What matters is noticing symptoms that are new, persistent, or unusual for you and discussing them with a healthcare provider.

We've covered the symptoms, risk factors, and what to do if you're concerned in our guide, Ovarian Cancer: Know the Red Flags.

"Ovarian cancer" isn't actually one disease

Here's another important piece of the puzzle: what we casually call ovarian cancer is actually a group of different cancers. They don't all behave the same way, and they don't all have the same prognosis.

For example, five-year survival is considerably higher for germ cell and stromal ovarian cancers than it is for epithelial ovarian cancer.

And then there's another twist. Some cancers we've historically called ovarian cancers may not actually begin in the ovary.

Research has shown that many high-grade serous cancers—the most common and aggressive form of epithelial ovarian cancer—appear to originate in the fallopian tubes.

That discovery has already changed thinking around ovarian cancer prevention and is one reason opportunistic salpingectomy—the removal of the fallopian tubes during another appropriate pelvic surgery—is increasingly discussed as a risk-reduction strategy.

It's also an excellent example of why fundamental research matters. Sometimes improving cancer outcomes starts by realizing we've been looking in the wrong place.

We're still learning how the ovary works

Which brings us to one of the more fascinating reproductive-health stories to make its way around social media recently: the rete ovarii.

If you've never heard of it, you're in very good company.

The rete ovarii is a structure associated with the ovary. Scientists have known it exists for a long time—it even appeared in older editions of Gray's Anatomy—but it was largely dismissed as a vestigial remnant without much function in the adult ovary.

Recent research suggests that assumption may have been premature.

In a 2025 study published in eLife, researchers examined the rete ovarii in mice and identified three distinct regions that persist into adulthood. They also found evidence suggesting that parts of the structure are secretory, interact with blood vessels, immune cells, and nerves, and may play a role in ovarian development and function.

That's fascinating. It is not, however, evidence that scientists have suddenly discovered a new organ, nor does it prove that the rete ovarii causes ovarian cancer, infertility, PCOS, menopause symptoms, or anything else you may have encountered while scrolling social media.

The research is early, and much of it was conducted in mice.

What it does tell us is arguably more interesting: something associated with the ovary that medicine has known about for generations may be more biologically important than we previously realized.

We'll be digging much deeper into the rete ovarii in a separate article, because it deserves more than a paragraph—and because the actual science is considerably more interesting than the social-media version.

Why are there still so many gaps in ovarian health research?

The rete ovarii isn't the explanation for ovarian cancer's stubborn survival statistics. But these stories belong in the same conversation.

We're trying to diagnose and treat diseases affecting an organ whose basic biology researchers are still actively investigating.

That's not a reason to distrust medicine. It's a reason to understand how science actually works. Medicine isn't a finished textbook containing everything there is to know about the human body. Knowledge changes as researchers ask better questions, develop better technology, revisit old assumptions, and—critically—receive funding to investigate them.

Ovarian cancer is a particularly powerful reminder of why that matters.

What is the survival rate for ovarian cancer in Canada?

The five-year net survival rate for ovarian cancer in Canada is approximately 44%. But that number needs context.

"Five-year survival" isn't an expiration date, nor can it predict what will happen to an individual person. It's a population-level statistic. Survival also varies dramatically depending on the type of ovarian cancer, how far it has spread when diagnosed, tumour biology, age, overall health, treatment, and other factors.

If we can't screen for ovarian cancer, what can we do?

Here's one of the more frustrating realities of ovarian cancer: we don't currently have an effective screening test for the general population. So one of the most successful prevention strategies we've developed involves surgery.

British Columbia has actually been at the forefront of this work. In 2010, researchers in B.C. began recommending opportunistic salpingectomy—removing both fallopian tubes while leaving the ovaries intact—when someone is already undergoing certain gynecological surgeries, such as a hysterectomy for a benign condition or permanent sterilization.

Why remove the fallopian tubes to prevent something called ovarian cancer? Because research has fundamentally changed our understanding of where the most common and deadly form of ovarian cancer begins. Many high-grade serous cancers are now believed to originate in the fallopian tubes, particularly at their fimbriated ends, before involving the ovary.

And the strategy appears to be working.

Research published in 2026 found that opportunistic salpingectomy was associated with nearly an 80% reduction in the risk of serous ovarian cancer compared with similar surgeries where the fallopian tubes were left in place.

That's an extraordinary advance in prevention—and importantly, the ovaries remain intact, avoiding the consequences of surgically induced menopause that can occur when both ovaries are removed before natural menopause.

For people at substantially increased hereditary risk of ovarian cancer, the recommendations can be different. Risk-reducing bilateral salpingo-oophorectomy (BSO)—removal of both fallopian tubes and ovaries—is recommended for some people with high-risk genetic variants, including BRCA1 and BRCA2, after childbearing is complete and at an age determined by their individual risk.

But there's something worth sitting with here. For the general population, one of our most effective ovarian cancer prevention tools is an operation performed opportunistically because someone is already having surgery.

That's valuable. It's saving cancers from developing. But it isn't screening. It can't help everyone, and it underscores just how significant the gap remains. We need better ways to identify ovarian cancer earlier—ideally through reliable, evidence-based screening or early-detection tools that don't depend on someone already being on an operating table.

Until then, prevention, understanding individual risk, knowing the symptoms, and continued investment in ovarian cancer research remain critically important.

There is still much more to learn about the ovary

Awareness months can sometimes become an exercise in changing profile pictures, sharing an infographic, and moving on. Ovarian cancer deserves more than that.

Knowing the symptoms matters. Understanding your family history matters. Knowing that a Pap test doesn't screen for ovarian cancer matters.

But awareness should also mean asking why ovarian cancer remains so difficult to detect and treat—and supporting the research trying to change that.

Because ovarian health research isn't finished. Not even close.

We're still learning where some ovarian cancers begin. We're developing new approaches to prevention and treatment. And researchers are taking another look at structures such as the rete ovarii that have been sitting quietly in anatomy books—or disappearing from them—for more than a century.

There is still a lot we don't know about the ovary. That's not a reason for fear. It's a reason to keep asking questions.

Resources and further reading

• Ovarian Cancer Canada: Canadian ovarian cancer information, support, advocacy, and research.

• Canadian Cancer Society — Ovarian cancer: Evidence-reviewed information on ovarian cancer symptoms, diagnosis, treatment, survival, and Canadian statistics.

• Canadian Cancer Society — Finding ovarian cancer early: Information about early detection, testing, and ovarian cancer risk.

• About Opportunistic Salpingectomy: British Columbian innovation reducing ovarian cancer rates by 80%

• Anbarci DN, McKey J, Levic DS, et al. (2025): "Rediscovering the rete ovarii, a secreting auxiliary structure to the ovary." eLife.

• eLife — "Ovarian Biology: Revisiting the rete ovarii" (2025): An accessible scientific commentary discussing what the rete ovarii research may mean for our understanding of ovarian biology.

• joni — Ovarian Cancer: Know the Red Flags: Our guide to ovarian cancer symptoms, risk factors, prevention, and advocating for your health.