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The quantitative sensitivity and dynamic range of conventional immunohistochemistry (IHC) with 3,3′-diaminobenzidine (IHC-DAB) used in pathological diagnosis in hospitals are poor, because enzyme activity can affect the IHC-DAB chromogenic reaction. Although fluorescent IHC can effectively increase the quantitative sensitivity of conventional IHC, tissue autofluorescence interferes with the sensitivity. Here, we created new fluorescent nanoparticles called phosphor-integrated dots (PIDs). PIDs have 100-fold greater brightness and a more than 300-fold greater dynamic range than those of commercially available fluorescent nanoparticles, quantum dots, whose fluorescence intensity is comparable to tissue autofluorescence. Additionally, a newly developed image-processing method enabled the calculation of the PID particle number in the obtained image. To quantify the sensitivity of IHC using PIDs (IHC-PIDs), the IHC-PIDs method was compared with fluorescence-activated cell sorting (FACS), a method well suited for evaluating total protein amount, and the two values exhibited strong correlation (R = 0.94). We next applied IHC-PIDs to categorize the response to molecular target-based drug therapy in breast cancer patients. The results suggested that the PID particle number estimated by IHC-PIDs of breast cancer tissues obtained from biopsy before chemotherapy can provide a score for predicting the therapeutic effect of the human epidermal growth factor receptor 2-targeted drug trastuzumab.

The associations between menstrual and reproductive factors and breast cancer risk in relation to estrogen/progesterone receptor (ER/PgR) status have been unclear in Japanese women. This case-control study evaluated these associations, overall and separately, by menopausal status. A total of 1092 breast cancer cases and 3160 controls were selected from among female patients aged 30 years and over admitted to a single hospital in Miyagi Prefecture between 1997 and 2009. The receptor status distribution among the cases (missing: 8.4%) was 571 ER+/PgR+, 133 ER +/PgRÀ, 24 ERÀ/PgR+ and 271 ERÀ/PgRÀ. Menstrual and reproductive factors were assessed using a self-administered questionnaire. Polytomous logistic regression and tests for heterogeneity across ER+/PgR+ and ERÀ/PgRÀ were conducted. Later age at menarche was significantly associated with a decreased risk of both ER+/PgR+ and ERÀ/PgRÀ cancer among women overall (P trend = 0.0016 for ER+/PgR+; P trend = 0.015 for ERÀ/PgRÀ) and among postmenopausal women (P trend = 0.012 for ER+/PgR+; P trend = 0.0056 for ERÀ/PgRÀ). Nulliparity was associated with an increased risk of ER+/PgR+, but not ERÀ/PgRÀ cancer among women overall (P heterogeneity = 0.019) and among postmenopausal women (odds ratio for ER+/PgR+ = 2.56, 95% confidence interval = 1.61-4.07; P heterogeneity = 0.0095). A longer duration of breastfeeding tended to be associated with a decreased risk in all subtypes among women overall. Later age at menarche has a protective effect against both ER+/PgR+ and ERÀ/PgRÀ cancer. However, parity might impact differently on various subtypes of breast cancer. Further studies are needed to clarify the etiology of the rare ER+/PgRÀ and ERÀ/PgR+ cancer subtypes. (Cancer Sci 2012; 103: 1861-1870 O ver the past few decades, numerous epidemiologic studies of breast cancer have been conducted, based mainly on Caucasian populations. These studies show that menstrual and reproductive factors and menopausal status are associated with breast cancer risk.(1,2) In Japan, cohort studies, (3,4) casecontrol studies (5)(6)(7) and a meta-analysis have revealed similar associations. (8) Breast cancers are known to express the estrogen receptor (ER) or progesterone receptor (PgR). Tumor subtypes defined by these receptors represent biologically different entities.(9) In Western countries, many studies have evaluated breast cancer risk according to hormone receptor status.(10-13) A meta-analysis shows that nulliparity is associated with a higher risk of ER+ tumors, but not ERÀ tumors.(13) Another meta-analysis suggests that nulliparity is associated with an increased risk of ER+/PgR+ tumors, but not ERÀ/PgRÀ tumors. The protective effects of late age at menarche and longer duration of breastfeeding do not differ across ER/PgR status. (12) Among studies conducted in the Asian region, a large-scale case-control study from China evaluates risk factors defined according to the four types of hormone receptor status and finds an association with parity history similar to that in the abovemention...