Ovarian cancers may begin in the fallopian tube

By Megan Rauscher

NEW YORK (Reuters Health) - New research suggests that fallopian tube cells rather than ovarian surface cells are the probable site of origin of most cases of ovarian serous carcinoma, the most common type of ovarian cancer.

This finding may lead to earlier detection, as well as better treatment and perhaps prevention, of ovarian cancer, Dr. Keren Levanon of the Dana Farber Cancer Institute in Boston told the annual gathering of the American Association for Cancer Research in San Diego.

As there is no early diagnostic test for ovarian cancer, roughly 80 percent of cases are diagnosed at a very late stage. "One fascinating fact," Levanon highlighted, "is that when you diagnose ovarian cancer you find massive invasive tumors on the surface of the ovary -- usually the tumor does not invade the ovary -- but you never find early pre-invasive in situ tumors."

"We do not believe that these invasive tumors arise as invasive cancers," she said, adding that "the foundation of our research is to look for precursor lesions." Precursor lesions are clusters of irregular cells representing the stage just before the formation of cancer cells -- in this case, ovarian cancer cells.

Levanon and colleagues studied a group of women at very high risk for ovarian cancer due to family history who underwent removal of their fallopian tubes and ovaries as a preventive measure.

When these women were closely evaluated, the researchers found that they had early cancerous growths -- and these early growths were in the fallopian tube, not on the surface of the ovary, Levanon said.

"Even more surprisingly," she said, the growths were confined to a particular area within the fallopian tube called the fimbria, which is located close to the ovary.

Levanon said these early precursor cell clusters were in "close to 100 percent" of the fallopian tubes in a group of women who already had ovarian cancer.

These data, the researcher said, "support our hypothesis that ovarian cancer originates in the fallopian tube and exfoliates or falls over the surface of the ovary and that's why these tumors develop on the surface of the ovary and not inside the ovary."

She hopes these data help in the design of future studies aimed at gaining a greater understanding of the basic process involved in the origin and growth of serous ovarian carcinoma, which could lead to targeted therapies and perhaps prevention strategies.