Rates of estrogen receptor-alpha expression are no different in low-risk (Vietnam) and high-risk (Australian) breast cancer.
Past studies have led to the view that positive estrogen receptor-alpha (ERa) expression is present in a 20% higher proportion of breast cancer in postmenopausal, but not premenopausal, women from populations with a high risk of breast cancer such the United States compared with populations with a low risk of breast cancer such as Japan. Data from the early studies that compared ERa expression in breast cancer specimens from Japanese and US women may not be reliable because no account was made of differing methods of laboratory analysis, grade (which has a profound influence on ERa expression), type of breast cancer, and threshold value (the cutoff level of Era-positive cells that defines positivity or negativity). We hypothesized that if these variables were standardized, there would be little or no difference in ERa expression in breast cancer in women from populations at low and high risk of breast cancer. Immunohistochemical analysis of ERa was conducted on formalin-fixed, paraffin-mounted, invasive breast cancer biopsy specimens from 107 Vietnamese (Hanoi) and 201 Australian subjects, which has enabled us to make valid comparisons of ERa expression between women from populations at very low and very high risk of breast cancer. There was no statistically significant difference in the percentage of ERa-positive breast cancer specimens between Vietnamese and Australian subjects for each 5-year age group, except the age group 51 to 55 years. For this age group, the percentage of ERa-positive specimens was significantly higher among the Vietnamese specimens. Our research question was, "When the known variables influencing ERa expression in breast cancer are standardized, is there any difference in ERa expression in breast cancer in women from populations at low and high risk for breast cancer?" The answer is, with respect to Vietnam, no. We have observed that ERa expression in breast cancer among Vietnamese women is higher than previously believed. It is possible that ERa expression in breast cancer among women from other developing countries is also higher than previously believed. The implication is that estrogen modulators such as tamoxifen, which are effective in the treatment of ERa-positive breast cancer, probably have a substantial role in developing and developed countries.
Tran
Dinh
D
Department of Anatomical Pathology, St. Vincent's Hospital, Australia.
Lawson
James
J
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000951:Antigens, Neoplasm / Q000032:analysis*; D001315:Australia / Q000453:epidemiology; D001943:Breast Neoplasms / Q000737:chemistry / Q000473:pathology*; D047628:Estrogen Receptor alpha; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000032:analysis*; D012015:Reference Standards; D012189:Retrospective Studies; D012306:Risk; D014744:Vietnam / Q000453:epidemiology
D000951:Antigens, Neoplasm; D047628:Estrogen Receptor alpha; D011960:Receptors, Estrogen