Ovarian cancer is the fifth largest killer of women, with a woman having a 1 in 75 chance of contracting it and a 1 in a 100 chance of dying from it. Who contracts it – and who survives – often comes down to who has it diagnosed the earliest.

If the disease is diagnosed in the early stages, before it has spread beyond the ovaries, then the survival rate is estimated at 92 percent. But the American Cancer Society notes that only 15 percent of ovarian cancers are diagnosed this early.

But now scientists believe they may have identified 12 genetic variations that raise the likelihood of epithelial ovarian cancer. Epithelial cancer is the most common kind of ovarian cancer, affecting the tissue that covers the ovaries.

An international team of researchers, representing the U.S., United Kingdom and Australia, have identified what amount to faulty genes which correlate to high incidence of ovarian cancer. This inherited genetic baggage accounts for a significant portion of a woman's risk of developing the disease.

"We know that a woman's genetic makeup accounts for about one third of her risk of developing ovarian cancer. This is the inherited component of disease risk. We are less certain of environmental factors that increase our risk, but we do know that several factors reduce the risk of ovarian cancer, including taking the oral contraceptive pill, having your tubes tied, and having children," noted co-lead author Professor Paul Pharoah.

The scientists used the dataset compiled by the OncoArray Consortium, which contains almost 450,000 genomic samples assembled in an attempt to identify the genetic background for most common cancers.

"Ovarian cancer is clearly a very complex disease - even the 30 risk variants that we now know increase risk of developing the disease account for just a small fraction of the inherited component. We believe that there will likely be many more genetic variants involved, each with extremely small effects. Most of these are likely to be common, but some will be rare," wrote Dr. Catherine Phelan, the study's first author.

The more scientists learn about the inheritable, genetic variants of cancers – ovarian or any kind – the better decisions they can make regarding prediction and prevention. Currently, women who are deemed to have a lifetime risk of 10 percent or more of contracting ovarian cancer are typically offered the option of having their ovaries removed.

The study was published in the journal Nature Genetics.