I guess it depends on whether one is thinking in terms of ANY hormone-receptor positivity (ER/PR) or just ER or just PR....?
"In agreement with previous studies (32,33), we found an inverse
relationship between ER/PR expression and HER2 (Table IV).
ER/PR positive tumors tend to lack HER2 overexpression
and conversely, HER2 overexpressing tumors tend to be
ER/PR negative...."
http://147.52.72.117/IJO/2001/volume.../1155-1160.pdf
and in a study of 366 women, "ER-positive and HER2-negative tumors were found in 221 patients (60.4%), ER-negative and HER2-negative in 71 (19.4%), ER-negative and HER2-positive in 46 (12.6%), and ER-positive and HER2-positive in 28 (7.7%)".
http://meeting.jco.org/cgi/content/a...3/16_suppl/900
Out of the 366, 249 (68.1%) were positive for ER and 74 (20.2%) were positive for HER2.
60.4% ER+, HER2-
19.4% ER-, HER2-
12.6% ER-, HER2+
7.7% ER+, HER2+