Women stand a better chance of surviving breast cancer if they are over 40 years old when diagnosed, new research released Wednesday showed.

The Australian study confirmed that survival rates are higher for those women who detect the tumour early, and for those with smaller tumours.

Researchers from the Australian Institute of Health and Welfare and the National Breast Cancer Centre looked at the survival rates of more than 10,000 women who were diagnosed with the disease in 1997.

They found that the larger the cancer, the lower the chance of survival.

Women whose cancers were 10 millimetres or less in diameter at diagnosis had a 98 percent chance of being alive five years later.

'This declined to 73 percent for women with cancers 30 millimetres or more in diameter, and to 49 percent for women with advanced cancer where size had not been measured,' said the institute's Christine Sturrock.

Survival rates were higher if the cancer was detected before it spread to the lymph nodes while age was also a significant influence, with women under 40 having a lower survival rate, no matter what size the tumour.

For these younger women, those with cancers 10 millimetres or less had a 95 percent survival rate while those whose growths had passed 30 millimetres had only a 67 percent chance of survival.

The director of the National Breast Cancer Centre, Dr Helen Zorbas, said the best outcomes appeared to be for those women diagnosed in their 50s.