Editor—Mayor reports the findings of a postal survey showing an alarming wide variation in rates of oestrogen receptor positivity in women with breast cancer.1 The results of this questionnaire showed that the rate of breast tumours positive for oestrogen receptor that were detected at different breast cancer centres varied from as low as 5% to around the expected 80%.
For several years the UK National External Quality Assessment Scheme for Immunocytochemistry has been regularly assessing the quality of oestrogen receptor staining, but only recently has the number of laboratories participating in this module reached 173. Currently we have identified 24 of these as having difficulty with their oestrogen receptor assays. These laboratories will be offered an opportunity to visit the scheme's centre at University College London and given help. Those who fail to improve will be referred to the national quality assessment advisory panel for remedial action.
Clinical Pathology Accreditation will be asked to ensure that those laboratories that are performing oestrogen receptor testing but are not currently participating in the oestrogen receptor module do so with immediate effect.
A further study, based on the returns obtained from 48 laboratories registered with the UK National External Quality Assessment Scheme for Immunocytochemistry and covering oestrogen receptor analysis of over 7000 breast carcinomas, also recorded a variation in rates of oestrogen receptor positivity.2 These rates fell within a more acceptable range of 44-90%, with the expected mean of 75% (95% confidence interval 73% to 78%).
Scrutiny of the methodologies used by the participants in the UK National External Quality Assessment Scheme for Immunocytochemistry showed that the lower positivity rate was largely due to the lower sensitivity of the assay used. This lower sensitivity in turn was principally due to a lower power of the antigen retrieval method applied. Adjustment of this factor conducted under the guidance given by the quality assessment scheme significantly improved the sensitivity of the assays performed by centres getting the poorer results.3
References
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- 3.Rhodes A, Jasani B, Balaton AJ, Barnes DM, Anderson E, Bobrow LG, et al. Study of interlaboratory reliability and reproducibility of estrogen and progesterone receptor assays in Europe: documentation of poor reliability and identification of insufficient microwave antigen retrieval time as a major contributory element of unreliable assays. Am J Clin Pathol. 2001;115:44–58. doi: 10.1309/H905-HYC1-6UQQ-981P. [DOI] [PubMed] [Google Scholar]