Breast cancer and the MNSs blood groups

Breast cancer has been reported to be associated with the Ss blood group system and specifically the ss blood genotype. This report was not substantiated by further work which concluded that the difference between the two studies may have been due to different aetiological factors in the two groups of patients studied. Breast cancer has a familial element so we decided to study the Ss and MN blood groups in familial and sporadic breast cancer patients and normal women with a positive family history along with a control group. We observed an increased incidence of the SS blood genotype in familial, sporadic breast cancer patients and women at an increased risk of developing breast cancer compared with a control group.