Younger women with ovarian cancer have better survival rates than older patients, even if they have surgery to conserve their fertility, scientists said on Tuesday.

Ovarian cancer is known as the silent killer because it is often not detected until the illness is in an advanced stage and more difficult to treat.

But an American study showed that 59 percent of women diagnosed between the ages of 30-60 were still alive five years later, compared to only 35 percent of older women with the illness.

Ovarian cancer is rare in women under 30 but the 5-year survival rate for that age group was 79 percent. “We found that younger patients have a better survival..,” said Dr John Chan of Stanford University in California, in the British Journal of Cancer.

Although the improved survival of young women could be due in part to an earlier diagnosis and a lower grade of tumour, Chan and his team believe there may be other underlying, unknown factors linked to the improved prognosis.

The researchers also found no significant difference in the survival of women of childbearing age who had been treated with surgery to conserve their fertility and those who had their wombs removed.

“Our results suggest that more pre-menopausal women diagnosed with ovarian cancer can be considered for fertility-sparing surgery,” said Chan.

“Also, given the overall encouraging survival rates in this age group, we can potentially make a significant impact on the outcomes of these young women with novel strategies,” he added.

About 190,000 new cases of ovarian cancer occur worldwide each year and 114,000 women die of the illness. The highest rates are reported in Scandinavia, Eastern Europe, the United States and Canada, according to the International Agency for Research on Cancer (IARC) in Lyon, France.

A family history of the illness is the most important risk factor and occurs in 5-10 percent of cases.

The illness is influenced by hormones. Early puberty, late menopause, a history of breast cancer and not having children may increase the odds of developing it.

Chan’s findings are based on an analysis of the medical history of 28,000 American women who had been diagnosed with ovarian cancer between 1988 and 2001.

The scientists called for more research into the potential biological and molecular differences that could account for the disparity in survival rates among the age groups.