Abstract
This study is an analysis of natural killer cell (NK) function in 155 women repeatedly tested over a 5‐year period while attending breast screening clinics because of one or more of the following risk factors: family history breast cancer in a close female relative (relative risk = 1.2‐9); personal history ‐ early menarche, non‐parity, late menopause, etc (relative risk = 1.3‐3); clinical benign breast syndrome ‐ localized and diffuse (relative risk = 2‐4). Contrary to expectations, the high‐risk group as a whole had significantly higher than normal relative NK function vs K562 (1.21 ± 0.06 vs 1.00 ± 0.06) (p<0.02). Division into subgroups showed that the NK activities in patients with positive family histories, personal histories, or both, were exactly the same as normal values and that the increased NK function in the high‐risk group as a whole was due to those donors with benign breast syndrome (BBS). This group was also subdivided and the results were compared with the high‐risk patients with no BBS. The NK activity of the group having diffuse BBS (1.67 ± 0.05, n = 32) was significantly higher than that of the “No BBS” group (1.07 ± 0.07, n = 102) (p<0.025). A paired “ℓ”‐test performed on data from 7 patients who had no BBS and diffuse BBS at different times showed a significant difference of p<0.001, suggesting that the elevated NK activity is a reaction to the hormonal factors which cause this condition.