The greatest reduction in risk was seen in invasive oestrogen receptor-positive breast cancer ( HR @ -LSB- @ % CI @-@ @ -RSB- , p < @ ) and ductal carcinoma in situ ( @ -LSB- @-@ @ -RSB- , p = @ ) , but no effect was noted for invasive oestrogen receptor-negative breast cancer ( HR @ -LSB- @ % CI @-@ @ -RSB- , p = @ ) .