Effect of operative devascularization on estrogen and progesterone receptor levels in breast cancer specimens.

To compare estrogen and progesterone receptor values between biopsy and mastectomy specimens, we prospectively studied 29 patients with breast cancer treated by incisional biopsy followed by mastectomy. The average tumor size was 5.4 +/- 0.5 cm and the mean age was 57.6 +/- 3.0 years. Nine patients were premenopausal and 20 were postmenopausal. Biopsies were performed without electrocautery, and tissue samples were promptly frozen and subsequently assayed for estrogen and progesterone receptor levels. After mastectomy, samples of residual tumor were excised from the biopsy site, promptly frozen, and assayed for estrogen and progesterone receptor levels. Operating time averaged 87.7 +/- 6.0 minutes. Estrogen receptor levels averaged 100.0 +/- 24.4 femtomole per mg on biopsy specimens and 29.5 +/- 8.2 fmol/mg on mastectomy specimens, representing a 70% decline (p less than 0.02). Of clinical significance is the fact that eight of 29 (27.6%) tumors changed from positive estrogen receptor values in the biopsy specimen to negative (four) and borderline (four) in the mastectomy specimens. Progesterone receptor levels were more variable, but their mean value decreased by 24.4% from 17.6 +/- 6.4 fmol/mg on biopsy samples to 13.3 +/- 4.3 fmol/mg on mastectomy samples (p, not significant). We conclude that the biopsy specimen is usually a more reliable indicator of hormonal receptor status than the mastectomy specimen and recommend that incisional or excisional biopsy specimens be taken for estrogen and progesterone receptor assays before mastectomy.