Researchers at the Stanford University School of Medicine have found that the reduced effectiveness of breast screening in women in their 40s is mainly due to their tumours being harder to detect, rather than because they grow faster. Previous research has suggested that breast screening is less effective in women in their 40s than in older women.
New findings on breast screening
Two reasons have been identified – firstly, that younger women tend to have denser breast tissue which makes it harder to detect tumours on a mammogram; and secondly, because younger women's tumours tend to grow more quickly. The researchers concluded that lower tumour detectability accounted for 79% of the reduced sensitivity of breast screening in younger women, while faster tumour growth accounted for just 21%.
