Data released by the NHS Information Centre showed that 5,913 invasive cancers under 15 millimetres across were detected. These accounted for two fifths of all breast cancers.
Tim Straughan, chief executive of the NHS Information Centre, said the findings highlight the 'vital impact' of the national screening programme in detecting breast cancers.
The number of small invasive cancers detected, as well as the total number of cancers detected overall has risen since last year. More than two million women aged 50 to 70 were invited to attend a screening. Of those, 73% took up the invitation.
Julietta Patnick, director of the NHS Cancer Screening Programmes, said catching small cancers earlier can help save lives.
'When found, these smaller cancers are generally earlier in their development and are more likely to respond to treatment, meaning that treatment is more likely to be effective,' she said.
'This is how screening reduces mortality and increases likelihood of survival.'