Randomized non-inferiority trial involving 45-year-old women attending breast cancer screening

Breast cancer screening is effective in reducing mortality from the disease. However, the sensitivity of mammography is not optimal, which limits the effectiveness of screening, particularly in younger women. In Italy, a one-year screening interval is recommended for all women aged 45-49, although it is likely that only women with dense breasts would benefit from such a short interval. For women aged 70-74, longer intervals may be more appropriate, in line with recent European recommendations. Italian regions are planning to expand the screening target population to include women aged 45-49 and 70-74.The MISS trial aims to determine the optimal screening interval for women aged 45. It is a non-inferiority trial that randomizes women aged 45 into three arms with a 1:1:1 ratio: a) a 1-year interval, b) a 2-year interval, and c) a tailored interval based on breast density. Women with very dense breasts (BI-RADS category D) are assigned to the 1-year screening interval, while women with non-dense or moderately dense breasts (BI-RADS categories A, B, and C) are assigned to the 2-year interval.

The study (NCT04590560) is ongoing. Thus, only minimal baseline data are published.