One in three women may need more regular mammograms to detect breast cancer, although screening for the over-70s could do more harm than good, research suggests.
In the first of two studies presented at a major conference, experts concluded that while screening every three years is right for most women, around a third are at higher risk of developing cancer and might benefit from yearly mammograms.
Professor Gareth Evans, from the University of Manchester, said working out the risk of breast cancer for individual women would help target screening more effectively.
His team analysed data on more than 50,000 women and found that the risk of developing breast cancer in the next decade typically varied from 2.4pc at the age of 47 to 3.5pc at the age of 70 for most women.
Prof Evans told the European Breast Cancer Conference in Glasgow: "Our results suggest that three-yearly screening is very effective for around 70pc of the female population, but that those women who have a higher than average risk of developing breast cancer probably require more frequent screening, particularly as more advanced cancers were detected in these women."
A second study found that the harm of screening may outweigh the benefits for women aged 70 and over.
The study from the Netherlands found that extending screening programmes to older women resulted in a large proportion being "over-treated".