High expression of the trefoil protein TFF1 in interval breast cancers

Breast cancer screening is important for the early detection of breast canc er. Tumors that become symptomatic in the screening interval are known as i nterval cancers but the reasons for their rapid progression are unknown. Es trogen receptor expression is lower in interval cancers suggesting that the y may have reduced hormonal responsiveness. To investigate this hypothesis we have measured the expression of the estrogen receptor and three estrogen -responsive genes (cathepsin D, progesterone receptor, and TFF1) in screen- detected and interval breast cancers. The expression of the protease cathep sin D was not associated with estrogen receptor in either group of tumor. P rogesterone receptor expression was highly correlated with that of the estr ogen receptor in both groups of tumors but it was not expressed at signific antly different levels in the two groups of tumors. Expression of TFF1, a c ellular motogen, was correlated with estrogen receptor in screen-detected b ut not interval cancers and was expressed at markedly higher levels in inte rval breast tumors,the group that expresses Lower levels of estrogen recept or. Interval cancers are characterized by high levels of expression of TFF1 and/or Ki67 suggesting that cell migration and cell division play importan t roles in the rapid progression of interval cancers. The observation that TFF1 expression in interval cancers tends to be estrogen-independent and th at interval cancers have reduced estrogen receptor expression suggests they may have a reduced response to hormone therapy.