US researchers have uncovered a type of cell in the ovaries of mice that, if also found in women, would represent the possible origin of the most common form of ovarian cancer.

If confirmed, the finding could lead to new insights into how the disease develops, and how to prevent it.

Epithelial ovarian cancer accounts for more than 90 per cent of ovarian cancers.

It derives its name from the fact that cancers were originally thought to begin growing in the layers of tissue that cover the ovary, called the epithelium.

Epithelium is one of the four basic types of animal tissue - along with connective tissue, muscle tissue and nervous tissue - and lines the cavities and organs throughout the body, as well as forming many glands.

But identifying the exact source of epithelial ovarian cancer has proved difficult since more than two-thirds (70 per cent) of patients are diagnosed once the disease is already in its advanced stages.

More recent evidence suggests some cancer may actually originate in cells from the fallopian tubes - the ducts that connect the ovaries to the womb.

Researchers at Cornell University found a 'stem cell' in mice responsible for generating the ovarian surface epithelium in a part of the ovary called the hilum, a layer of cells connecting the ovary to the fallopian tube.

The study is published in the journal Nature.

"We now know where these cells are located in mice, so we can look in humans in those areas," said Professor Alexander Nikitin, leader of the Cornell Stem Cell Program and the paper's senior author.

Professor James Brenton, a Cancer Research UK-funded ovarian cancer expert based at the charity's Cambridge Institute, called the findings "very intriguing and potentially important".

"Many 'ovarian' cancers actually arise in the fallopian tubes, but some appear to come from the ovary itself," Professor Brenton said.

"This study shows how ovarian cancers in mice can develop in stem cells from the ovary - the first time this has ever been proven."

He said research now needed to be done into whether these ovarian stem cells were found in women and if they played the same role in the development of human ovarian cancers.

"If they are, it could have important implications, particularly in explaining why the oral contraceptive pill lowers the risk of this cancer developing," he added.

"If we could understand that, we could be on the way to developing other drugs to prevent the disease - a very exciting prospect."

Source: CRUK