Transferrin receptor is inversely correlated with estrogen receptor in breast cancer.

The transferrin receptor (TfR) has been identified as a marker for proliferation in cells in culture and can be accurately quantitated by specific radioimmunoassay. This study directly quantifies levels of TfR and compares them to levels of estrogen receptor (ER) and progesterone receptor (PgR) in biopsy material obtained from patients with infiltrating ductal carcinoma of the breast. A comparison of ER and TfR levels displayed an exponential distribution which was log-normalized to yield a linear inverse relationship (r = -.44). Although ER was strongly correlated with PgR, there was no correlation pattern between TfR and PgR. Multiple regression analysis indicated that 73% of ER levels could be predicted by a combination of the other two markers, PgR (representing degree of differentiation) and TfR (representing growth rate). Transferrin receptor levels were also found to be correlated (p less than .05) with menopausal status, with tumors from premenopausal patients exhibiting higher levels, whereas the opposite pattern was shown for estrogen receptor levels (p less than .02). Neither steroid receptor nor transferrin receptor levels were correlated to stage of disease or presence of nodal involvement. Addition of TfR level as an independent marker for proliferation may facilitate the decision-making process in the treatment of individual cases of carcinoma of the breast.