Reproductive factors and breast cancer risk according to joint estrogen and progesterone receptor status: a meta-analysis of epidemiological studies

INTRODUCTION: Although reproductive factors have been known for decades to be associated with breast cancer risk, it is unclear to what extent these associations differ by estrogen and progesterone receptor (ER/PR) status. This report presents the first meta-analysis of results from epidemiological studies that have investigated parity, age at first birth, breastfeeding, and age at menarche in relation to ER(+)PR(+ )and ER(-)PR(- )cancer risk. MATERIALS AND METHODS: We calculated summary relative risks (RRs) and corresponding 95% confidence intervals (CIs) using a fixed effects model. RESULTS: Each birth reduced the risk of ER(+)PR(+ )cancer by 11% (RR per birth = 0.89, 95% CI = 0.84–0.94), and women who were in the highest age at first birth category had, on average, 27% higher risk of ER(+)PR(+ )cancer compared with women who were in the youngest age at first birth category (RR = 1.27, 95% CI = 1.07–1.50). Neither parity nor age at first birth was associated with the risk of ER(-)PR(- )cancer (RR per birth = 0.99, 95% CI = 0.94–1.05; RR of oldest versus youngest age at first birth category = 1.01, 95% CI = 0.85–1.20). Breastfeeding and late age at menarche decreased the risk of both receptor subtypes of breast cancer. The protective effect of late age at menarche was statistically significantly greater for ER(+)PR(+ )than ER(-)PR(- )cancer (RR = 0.72 for ER(+)PR(+ )cancer; RR = 0.84 for ER(-)PR(- )cancer, p for homogeneity = 0.006). CONCLUSION: Our findings suggest that breastfeeding (and age at menarche) may act through different hormonal mechanisms than do parity and age at first birth

Hormone-related risk factors for breast cancer in women under age 50 years by estrogen and progesterone receptor status: results from a case–control and a case–case comparison

INTRODUCTION: It has been suggested that hormonal risk factors act predominantly on estrogen receptor and progesterone receptor (ER/PR)-positive breast cancers. However, the data have been inconsistent, especially in younger women. METHODS: We evaluated the impact of age at menarche, pregnancy history, duration of breastfeeding, body mass index, combined oral contraceptive use, and alcohol consumption on breast cancer risk by ER/PR status in 1,725 population-based case patients and 440 control subjects aged 20 to 49 years identified within neighborhoods of case patients. We used multivariable unconditional logistic regression methods to conduct case–control comparisons overall as well as by ER/PR status of the cases, and to compare ER(+)PR(+ )with ER(-)PR(- )case patients. RESULTS: The number of full-term pregnancies was inversely associated with the risk of ER(+)PR(+ )breast cancer (p(trend )= 0.005), whereas recent average alcohol consumption was associated with an increased risk of ER(+)PR(+ )breast cancer (p(trend )= 0.03). Neither of these two factors was associated with the risk of ER(- )PR(- )breast cancer. Late age at menarche and a longer duration of breastfeeding were both associated with decreased breast cancer risk, irrespective of receptor status (all p(trend)≤ 0.03). CONCLUSION: Our results suggest that the number of full-term pregnancies and recent alcohol consumption affect breast cancer risk in younger women predominantly through estrogen and progesterone mediated by their respective receptors. Late age at menarche and breastfeeding may act through different hormonal mechanisms

Incense smoke: clinical, structural and molecular effects on airway disease

In Asian countries where the Buddhism and Taoism are mainstream religions, incense burning is a daily practice. A typical composition of stick incense consists of 21% (by weight) of herbal and wood powder, 35% of fragrance material, 11% of adhesive powder, and 33% of bamboo stick. Incense smoke (fumes) contains particulate matter (PM), gas products and many organic compounds. On average, incense burning produces particulates greater than 45 mg/g burned as compared to 10 mg/g burned for cigarettes. The gas products from burning incense include CO, CO2, NO2, SO2, and others. Incense burning also produces volatile organic compounds, such as benzene, toluene, and xylenes, as well as aldehydes and polycyclic aromatic hydrocarbons (PAHs). The air pollution in and around various temples has been documented to have harmful effects on health. When incense smoke pollutants are inhaled, they cause respiratory system dysfunction. Incense smoke is a risk factor for elevated cord blood IgE levels and has been indicated to cause allergic contact dermatitis. Incense smoke also has been associated with neoplasm and extracts of particulate matter from incense smoke are found to be mutagenic in the Ames Salmonella test with TA98 and activation. In order to prevent airway disease and other health problem, it is advisable that people should reduce the exposure time when they worship at the temple with heavy incense smokes, and ventilate their house when they burn incense at home