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November 21, 1977

Estrogen Receptor Assay-Reply

JAMA. 1977;238(21):2263. doi:10.1001/jama.1977.03280220031008

In Reply.—  Two crucial points regarding the use and interpretation of estrogen receptor results should be brought up after reading Dr Tashima's letter: (1) one should not accept the receptor results readily without understanding the method of assays, and (2) one should not depend on estrogen receptor assay solely and neglect the importance of clinical information as a whole in the management of patients.In the quoted report of McClendon et al,1 "estrogen receptor" in five colonic neoplasms were all less than 70 fmole/g of tissue. According to our experience and that of others,2 a substantial 8 S receptor peak usually could not be identified with confidence by sucrose gradient method when the receptor level was below 3 fmole/mg cytosol protein, or equivalent to about 100 fmole/g of tissue. Any claim for the presence of estrogen receptors below this level should be supported by Scatchard analysis and K