For decades, doctors believed that most ovarian cancers began in the ovaries. Research conducted over the past several years found instead that many cases of ovarian cancer actually begin in the fallopian tubes. This discovery has transformed how experts think about prevention and risk reduction, even as researchers continue searching for new targeted treatments.
In a recent conversation with Outcomes4Me, UCLA Health’s Dr. Beth Karlan explained why this shift in understanding has been so significant for patients.
A major shift in how we understand ovarian cancer
“I think this has been really transformative to how we think about ovarian cancer,” Dr. Karlan said.
One reason is that ovarian cancer isn’t a single disease. Different subtypes develop in different ways, and researchers now know they don’t all start in the same place.
For high-grade serous ovarian cancer (the most common type of ovarian cancer), evidence suggests that the earliest cancerous changes often occur in the far end of the fallopian tube rather than in the ovary itself.
Evidence-based guidance powered by NCCN Guidelines®
Personalized treatment plans shaped by the latest oncology standards—tailored to your diagnosis.
Get started
View your personalized treatment plan in the Outcomes4Me app
Use your diagnosis to unlock personalized NCCN Guidelines®-aligned recommendations.
Continue in app
Dr. Karlan explains that during ovulation, the release of an egg triggers enzymes that help the egg leave the ovary. Those same enzymes may also damage the delicate cells lining the end of the fallopian tube. Over time, some of these damaged cells can become cancerous.
“They often then implant on the ovary because there’s lots of good blood supply there,” she said. “That’s where they grow, and that’s why we’ve thought about it as ovarian cancer for all these years.”
By the time the cancer is discovered, it may be growing on the ovary, even though it started somewhere else.
Prevention is becoming the biggest breakthrough
Genetic changes, including mutations in TP53, are found in the vast majority of advanced cases, but Dr. Karln notes that “it’s been very difficult to target.”
Researchers have spent years testing therapies aimed at TP53, including gene therapy approaches, but so far these mutations have remained difficult to treat directly.
Dr. Karlan believes the greatest impact of this research has been in preventing cancer before it starts. “Even better than early detection is interception, never having the cancer at all,” she said.
Because many high-grade serous ovarian cancers begin in the fallopian tubes, physicians offer removal of the fallopian tubes (called a salpingectomy) during certain pelvic surgeries when appropriate. This may be done as a risk-reducing salpingectomy for people at increased genetic risk or as an opportunistic salpingectomy when someone is already undergoing surgery such as a hysterectomy for another reason.
According to Dr. Karlan, this discovery has changed medical practice in a meaningful way.
“We’ve changed the textbooks,” she said. “We’ve changed the way we teach our residents to do hysterectomy. The fallopian tube comes out every time you do a hysterectomy at this point.”
What if you have a BRCA mutation?
For people who carry an inherited BRCA1 or BRCA2 mutation, these findings may also expand conversations about risk reduction.
Traditionally, removing both the ovaries and fallopian tubes has been the most effective way to reduce ovarian cancer risk. However, because removing the ovaries causes immediate menopause, researchers have been studying whether removing the fallopian tubes first, with ovary removal at a later time in carefully selected patients, may offer an interim risk-reduction strategy.
“We know that removing the fallopian tubes as an interim step before you have your ovaries removed… can reduce your risk of ovarian cancer,” Dr. Karlan explained.
If you have a BRCA mutation or a strong family history of ovarian or breast cancer, it’s important to discuss your individual options with a genetic counselor and your healthcare team.
What does this mean for fertility?
For people who hope to have children in the future, discussions about removing the fallopian tubes or ovaries can understandably raise concerns about fertility.
If you’re at increased genetic risk for ovarian cancer but haven’t completed your family, talk with your healthcare team early about your options. A gynecologic oncologist and fertility specialist can help you understand the timing of risk-reducing surgery that balances cancer risk with your reproductive goals.
The importance of raising awareness
Understanding where ovarian cancer begins hasn’t yet led to a cure or dramatically changed treatment for advanced disease, but it’s reshaping how doctors think about preventing ovarian cancer before it starts. While researchers continue working toward better treatments, increasing awareness of ovarian cancer risk and prevention may help more people reduce their risk before cancer ever develops.
You can listen to our full ovarian cancer discussion with Dr. Karlan, here.
Personalized support for real care decisions
Understand your diagnosis, explore clinical trials, and track symptoms--all in one place.
Get started
Compare treatments, prepare for appointments, and track side effects—all in the app
Built for your diagnosis, Outcomes4Me gives you the tools to make confident, informed decisions—right when you need them.
Continue in app
