Re-evaluating Adjuvant Breast Cancer Trials: Assessing Hormone Receptor Status by Immunohistochemical Versus Extraction Assays

Abstract

Trial conclusions in which ER status (for all patients) or PgR status (for postmenopausal patients) was determined by immunohistochemical assay supported those determined by extraction assays. However, among premenopausal patients, trial conclusions drawn from PgR status differed--immunohistochemically determined PgR status could predict response to endocrine therapy, unlike that determined by the extraction assay.

Immunohistochemistry compared to cytosol assays for determination of estrogen receptor and prediction of the long-term effect of adjuvant tamoxifen

“…The subset of patients in trial IX is similar to our cohort but randomization was between chemotherapy followed by tamoxifen versus tamoxifen. The median duration of follow-up was shorter and biochemical assays were performed at different local pathology laboratories [19]. However our results confirm results from these cohorts.…”

“…Two retrospective adjuvant studies conducted on archival tissue, one by Ferno et al [30] on 98 patients which received adjuvant tamoxifen, the other reported by Harvey et al [31]showed that estrogen receptor positivity determined by IHC significantly predicted improved disease free survival in patients receiving adjuvant tamoxifen therapy. To our knowledge only three other studies [17][18][19] used randomized clinical trial populations receiving adjuvant therapy but the cohort of patients were smaller, had shorter duration of follow up and mixed treatment arms [17,18]. Regan at al re-evaluated and reported results from International Breast Cancer Study Group (IBCSG) trial VIII (pre-and perimenopausal patients) and trial IX (postmenopausal patients).…”

“…To our knowledge there are only few studies comparing these methods in an adjuvant randomized setting [17][18][19].…”

Increasing steroid hormone receptors expression defines breast cancer subtypes non responsive to preoperative chemotherapy

“…Recommendations for the selection of therapies in early breast cancer include the identification of different subtypes of breast cancer and, based on genetic profile and immunohistochemistry, the demonstration of selected targets [17,18]. Treatment strategy should focus mainly on targeted therapies wherever possible, though acknowledging that supplementation with less target-specific chemotherapy is often required [9].…”

Fractionated evaluation of immunohistochemical hormone receptor expression enhances prognostic prediction in breast cancer patients treated with tamoxifen as adjuvant therapy

“…Over the past decade, immunohistochemistry (IHC) has replaced the ligand-binding assay (LBA) for measuring ER and PR. Some studies comparing the predictive values of these two methods found that IHC is an equal or a superior method (Reiner et al, 1986;Stierer et al, 1993;Barnes et al, 1996;Harvey et al, 1999;Mohsin et al, 2004;Regan et al, 2006). However, the definitions of ER and PR positivity by IHC were not consistent among the different studies.…”