Most, and possibly all, ovarian cancers start not in the ovaries but instead the fallopian tubes attached to them, a US study has found.

Analysis of more than 20,000 genes identified in high-grade pelvic cancers found ovarian cancer cells have more in common with cells covering the tips of fallopian tubes than with those on the surface of ovaries.

If biological biomarkers can be found for these ‘tubal cells’, future blood tests, advanced Pap smears, or direct tests on tubal tissue might be able to detect ovarian cancer earlier, say the authors of the study published in Nature Communications.

Although this will take many years to prove, they note.

“Based on a better understanding of its origins, our study suggests new strategies for the prevention and early detection of ovarian cancer,” said senior study author Douglas Levine, director of the Division of Gynecologic Oncology at the Perlmutter Cancer Center and professor of Obstetrics and Gynecology at NYU School of Medicine.

Past studies have shown that cancer cells may arise from nearby tissue or may have spread to a location from another part of the body, but that their genetic profile reflects the tissue of origin.

To test this theory on ovarian cancer, researchers conducted in-depth molecular analyses of cells from 96 women with high-grade serous carcinoma – cancers within the pelvic cavity.

They failed to identify any genetic differences between cancer cells arising in the fallopian tubes and ovaries.

“We found no differences in the 20,000 genes that we can identify,” said Dr Levine.

“This leads us to believe that that these ovarian cancers all originate in the fallopian tubes.”

Ovarian cancer is more aggressive than many other cancers because it is hard to diagnose in its earliest – and most treatable – stages.

Fewer than 50 per cent of women diagnosed with the disease survive for longer than five years after their diagnoses, according to the Australian Cancer Council.

Dr Levine says the new findings, published in journal Nature Communications, also point to the possibility that removing a woman’s fallopian tubes, not her ovaries, may reduce risk of ovarian cancer in those at high risk for disease, including those with genetic changes known to increase risk such as the BRCA mutation.

“We are one of several centres taking part in Women Choosing Surgical Prevention or WISP trial, which seeks to determine whether removing the tubes improves quality of life, compared to removing both the tubes and ovaries,” Dr Levine said.

Clinical trials are being conducted to help determine if the knowledge of ovarian cancer origins can be translated into broader prevention approaches.

-AAP