Estrogen receptor-positive breast cancer in Japanese women: trends in incidence, characteristics, and prognosis.
BACKGROUND
The incidence of breast cancer in Japanese women has doubled in all age groups over the past two decades.


METHODS
We examined the characteristics of the tumors treated in three time periods between 1982 and 2010. Estrogen receptor (ER), progesterone receptor (PgR) and HER2 status were assessed by immunohistochemistry. Correlation of hormone receptor levels with clinicopathological factors and prognosis was analyzed in ER-positive, HER2-negative breast cancer in two age groups (≤50 years versus >50 years).


RESULTS
The frequency of ER-positive breast cancer in women aged 50 years or younger increased greatly over the interval studied (1982-1991: 52.5%, 1992-2001: 72.6%, 2002-2010: 87.1%, P < 0.0001). The frequency of ER-positive tumors also significantly increased in women over 50 years of age (1982-1991: 69.4%, 1992-2001: 73.3%, 2002-2010: 78.6%, P = 0.029). In ER-positive, HER2-negative breast cancer, tumor grade was negatively correlated with expression levels of ER and PgR. Prognosis for patients with ER-positive, HER2-negative disease significantly improved over time, due to advances in adjuvant therapies.


CONCLUSIONS
It is necessary to establish risk factors, both genetic and environmental, capable of predicting the risk of ER-positive breast cancer and thus enable the efficient selection of candidates for hormone receptor-targeted chemoprevention.
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya. Electronic address: hirokoy@med.nagoya-cu.ac.jp.
H
H
Yamashita
Department of Breast and Endocrine Surgery, Kumamoto University, Kumamoto.
H
H
Iwase
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya.
T
T
Toyama
Department of Experimental Pathology and Tumor Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
S
S
Takahashi
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya.
H
H
Sugiura
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya.
N
N
Yoshimoto
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya.
Y
Y
Endo
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya.
Y
Y
Fujii
Oncology, Immunology, and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya.
S
S
Kobayashi
D000328:Adult; D000367:Age Factors; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000097:blood; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000097:blood
D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human