title: Quality control of cathepsin-D measurement by the EORTC Receptor Study Group.
abstract: Cathepsin-D is a lysosomal protease that can serve as an important prognostic cytosolic factor in breast cancer. To evaluate the performance of a commercially available immunoradiometric assay kit, 15 lyophilised cytosol participating EORTC laboratories for preparations containing various levels of cathepsin-D have been sent to 13 participating EORTC laboratories for quality control purposes. The between-laboratory variation, when expressed as coefficient of variation, did not exceed 24%. The within-laboratory variation was assessed by analysing five samples of the 15 specimens containing lyophilised material from a homogeneous cytosol pool. The mean within-laboratory coefficient of variation was 7%. Analysis of human breast tumour cytosols in one of the participating EORTC laboratories resulted in a median within-assay variation between duplicate measurements of 2.1% (n = 408), with a between-assay variation of a pooled human breast tumour cytosol of 4.6% (n = 11).
authors.affiliation: Department of Experimental and Chemical Endocrinology, Sint Radboud Hospital, The Netherlands.
authors.forename: T J
authors.initials: TJ
authors.lastname: Benraad
authors.forename: A
authors.initials: A
authors.lastname: Geurts-Moespot
authors.forename: M
authors.initials: M
authors.lastname: Sala
authors.forename: A
authors.initials: A
authors.lastname: Piffanelli
authors.forename: A
authors.initials: A
authors.lastname: Ross
authors.forename: J A
authors.initials: JA
authors.lastname: Foekens
mesh_terms: D001943:Breast Neoplasms / Q000737:chemistry*; D002402:Cathepsin D / Q000032:analysis*; D003600:Cytosol / Q000737:chemistry; D005260:Female; D006801:Humans; D007753:Laboratories / Q000592:standards; D015588:Observer Variation; D011379:Prognosis; D011786:Quality Control; D011863:Radioimmunoassay
chemical_list: D002402:Cathepsin D