Background: Overexpression of HER-2/neu (HER) is associated with unfavorable prognoses in both endometrial and breast cancer.
Materials and methods: To determine whether an association exists between HER expression and markers of hormone dependency in endometrial cancers, we subjected hysterectomy specimens from 125 patients to immunohistochemical staining for HER. HER was visually interpreted as negative/weakly positive (HER-) versus strongly positive (HER+). Estrogen receptor (ER) and progesterone receptor (PR) levels were quantitated on fresh tissue using a dextran-coated charcoal assay.
Results: HER+ was observed in 12% of endometrioid tumors and 22% of nonendometrioid tumors (p = 0.07). Mean ER and PR levels were 255 fmol/mg and 457 fmol/mg in endometrioid tumors, compared with 74 and 104 in nonendometrioid tumors (p < 0.01). Hyperplasia associated with the tumor was related to high levels of both ER and PR (p < 0.05), but not with HER expression. Age was significantly related to high levels of ER (p = 0.007). Both recurrence and death rates were significantly associated with low levels of ER and PR (p < 0.01). Mean ER and PR levels were 270 and 466 fmol/mg, respectively, in HER-tumors, compared with 95 (p = 0.14) and 138 fmol/mg (p = 0.02) in HER+ tumors.
Conclusion: HER overexpression may be an important step in hormone-independent growth and proliferation in a subgroup of endometrial cancers.