Classification of findings in mammography screening--a method to minimise recall anxiety?

The aim was to find out if it is possible, by classifying screening mammograms according to the likelihood of malignancy, to divide the recalled women to a group in which there is high suspicion of malignancy, most having breast cancers, and a group with more obscure findings.

Screening mammograms of recalled women were classified according to the likelihood of malignancy. 0 = technically insufficient, 1 = normal, 2 = benign tumour, 3 = malignancy cannot be excluded, 4 = strongly suspicious for malignancy, 5 = malignant.

This study was a population based survey of mammography screening in Helsinki and surroundings in Finland.

21,417 women (aged 50-59 years) were invited to be screened, 18,012 (84.10%) participated. Of these 579 (3.21% of those screened) were recalled for further studies; 124 of these were referred for surgical biopsy and 82 had breast cancer.

All cases classified as 5, 60% of the cases classified as 4, 6.5% of the cases classified as 3, 0% of the cases classified as 2 or 1, and 1.2% of the cases classified as 0 proved to have breast cancers. However classification 5 represented 5.9% of all recalled women and 41.5% of all screening detected breast cancers; classification 4, 6.0% of all recalled women and 25.6% of all screening detected breast cancers; classification 3, 68.9% of all recalled women and 31.7% of all screening detected breast cancers; classification 2, 11.7% and classification 1, 2.9% of all recalled women. No breast cancers were detected with these classifications. Classification 0 represented 4.5% of all recalled women and 1.2% of all screening detected breast cancers. Classifications 5 and 4 represented only 11.9% of all recalled women but 67.1% of all screening detected breast cancers.

By classifying screening mammograms according to the likelihood of malignancy, recalled women can be divided into two groups: (1) a quite small subgroup in which everyone or almost everyone will be shown to have breast cancer; and (2) a much larger subgroup in which only a few will be proven to have breast cancer. The invitation procedure for the further studies should be improved on this basis of minimising anxiety among recalled women.