Linked Life Data

8251648

Source:http://linkedlifedata.com/resource/pubmed/id/8251648

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-1-12
pubmed:abstractText
Estrogen (ER) and progesterone receptor (PgR) positive breast tumors often respond to tamoxifen, but ultimately progress as they become tamoxifen resistant. An accurate assessment of receptor status in specimens from tamoxifen-resistant patients could help to understand potential mechanisms of resistance and to predict response to second line hormonal therapies. However, since tamoxifen itself can affect ER and PgR determinations, assay results can be misleading. We measured ER and PgR by both ligand binding (LBA) and immunohistochemical (IHC) assays in 34 tumors from patients on tamoxifen, 30 of whom were displaying resistance to the drug. These tumors were classified into several receptor phenotypes. Eleven patients, 8 of whom were clearly progressing, expressed both receptors while on tamoxifen. ER was significantly less often negative when measured by IHC, suggesting that ER status by LBA was falsely negative in this group due to receptor occupancy by tamoxifen. Six patients had no detectable ER by LBA or IHC but still expressed PgR. The presence of PgR suggests that ER could still be functional, though undetectable, in these tumors, or that PgR is constitutively expressed by them. Finally, 12 patients were ER and PgR-negative by both assays, suggesting hormonal independence as the mechanism for resistance in this group. In a subset of patients with receptor assays both prior to tamoxifen and at the time of progression while taking the drug, we found that most ER-positive tumors converted to an apparent ER-negative status when assayed by LBA, while PgR status frequently remained unchanged. The continued expression of ER and/or PgR in many patients with tumor progression on tamoxifen indicates that mechanisms for resistance other than receptor loss are common in breast cancer.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0167-6806
pubmed:author
pubmed:issnType
Print
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
237-46
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Measurement of steroid hormone receptors in breast cancer patients on tamoxifen.
pubmed:affiliation
Department of Medicine, University of Texas Health Science Center at San Antonio 78284-7884.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.