Tumours of breast cancer patients who are under the age of 60 are likely to grow at a faster pace, according to a new study by researchers in Norway.

The team of medical experts screened 400,000 breast cancer patients between the ages of 50 and 69 and found that the tumours of those in their 50s took less time to increase in size.

According to the scientists from the Cancer Registry of Norway, the tumours of 50 to 59 year olds took an average of 1.4 years to grow from 10mm to 20mm.

However, it took an average of 2.1 years for the tumours of older women who were in their 60s to increase in size by the same amount.

The results were compiled by using a new approach to breast cancer screening, which the researchers hailed as more accurate than previous models.

Their new estimating procedure predicts the growth rate of breast cancer at the same time as using mammography screening to detect tumours, the researchers said.

Harald Weedon-Fekjaer, who led the study, said that the results had "enormous implications" for the sensitivity of breast cancer screening programs.

"We found that mammography screen test sensitivity increases sharply with increased tumour size, as one might expect," he added.

"Detection rates are just 26 per cent for a 5mm tumour but increase to 91 per cent once a tumour is 10mm in size."

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