Difference in hormone receptor content in breast cancers from Vietnamese and Swedish women.

Background: The aim of the present study was to compare both estrogen (ER) and progesterone receptor (PgR) content in operable breast cancers from Vietnamese and Swedish patients.
Material and Methods: Primary breast cancer tissues were randomly selected from 249 Vietnamese patients treated in Hanoi, Vietnam between 2002 and 2004 and 1 257 Swedish patients treated in Stockholm, Sweden between 2002 and 2003. Clinical information was available for all patients in the study. The hormone receptor content in tumors from Vietnam was analyzed by immunohistochemistry using an automated slide stainer (Bench MarkXT, Ventana) in combination with anti-ER (SP1 250), and anti-PgR (clone 1E2) rabbit monoclonal antibody. Tumors with ≥ 10% stained nuclei were considered as receptor positive. Tumors from Swedish patients were analyzed with an enzyme immunoassay with a cut-off point of ≥ 0.10 fmol/μg DNA as positive. The hormone receptor frequencies between populations were compared according to clincopathology features.
Results: The ER positive rate was higher in premenopausal and lower in postmenopausal Vietnamese patients as compared to Swedish patients with similar menopausal status (71% versus 58%, OR 1.75, p = 0.007; 44% versus 72%, OR 0.32, p < 0.001, respectively). PgR positive tumors were found in 58% and 25% of pre- and postmenopausal Vietnamese patients, respectively. The corresponding figures for Swedish patients were 73% and 66%, respectively.
Conclusions: There were significant differences in the frequency of ER/PgR positivity between Vietnam and Swedish breast cancer patients. These differences were independent on menopausal status and age of patients at diagnosis can not be explained by these factors and they can be contributed to knowledge about both basic biology features and prognoses.