title: Epidermal growth factor receptor-negative tumors are predominantly confined to the subgroup of estradiol receptor-positive human primary breast cancers.
abstract: A total of 725 human primary breast tumor biopsy samples were analyzed for epidermal growth factor receptor (EGFR) content, using a multiple-point EGFR assay standardized in accordance with the recommendations of the European Organization for Research and Treatment of Cancer Receptor Study Group. After the establishment of a lower cell membrane protein threshold of 0.2 mg of membrane protein per ml of assay buffer, the results of 27% (194 samples) of the EGFR determinations were excluded from the study because of insufficient assay membrane protein content. Of the remaining 531 breast tumor biopsy samples, 57% (302 samples) were shown to be EGFR positive by Scatchard analysis, with a median value of 40 fmol/mg of membrane protein. Of the breast tumor biopsy samples, 72% (380 samples) were estrogen receptor (ER) positive, and 65% (344 samples) were progesterone receptor (PgR) positive. EGFR positivity was found in 46% (173 of 380) of ER-positive and in 85% (129 of 151) of ER-negative breast tumor biopsy samples (P less than 0.0001), as well as in 49% (168 of 344) of PgR-positive and in 72% (134 of 186) of PgR-negative breast tumor biopsy samples (P less than 0.0001). Mean EGFR levels in ER-positive breast tumor biopsy samples were lower than they were in ER-negative ones, 40 +/- 31 (SD) against 72 +/- 55 fmol/mg of membrane protein (P less than 0.0001). Similarly, mean EGFR levels in PgR-positive breast tumor biopsy samples were lower than they were in PgR-negative ones, 41 +/- 29 against 70 +/- 56 fmol/mg of membrane protein (P less than 0.0001). Both EGFR positivity and EGFR levels decreased with increasing steroid hormone receptor levels. A multivariate analysis showed only ER to be independently associated with EGFR.
authors.affiliation: Department of Experimental and Chemical Endocrinology, University Hospital of Nijmegen, The Netherlands.
authors.forename: P G
authors.initials: PG
authors.lastname: Koenders
authors.forename: L V
authors.initials: LV
authors.lastname: Beex
authors.forename: A
authors.initials: A
authors.lastname: Geurts-Moespot
authors.forename: J J
authors.initials: JJ
authors.lastname: Heuvel
authors.forename: C B
authors.initials: CB
authors.lastname: Kienhuis
authors.forename: T J
authors.initials: TJ
authors.lastname: Benraad
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry*; D015925:Cryopreservation; D066246:ErbB Receptors / Q000032:analysis*; D006801:Humans; D011379:Prognosis; D011959:Receptors, Estradiol / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis; D013997:Time Factors; D014021:Tissue Preservation
chemical_list: D014408:Biomarkers, Tumor; D011959:Receptors, Estradiol; D011980:Receptors, Progesterone; D066246:ErbB Receptors