Smoking is one of the well-established risk factors for gastric cancer incidence, yet whether men are more or equally susceptible to gastric cancer due to smoking compared with women is a matter of controversy. The aim of this study was to investigate and compare the effect of sex on gastric cancer risk associated with smoking. We conducted a systemic literature search in MEDLINE, EMBASE, and the Cochrane CENTRAL databases to identify studies published from inception to December 2018. We included prospective observational studies which reported effect estimates with 95% confidence intervals (CIs) for associations of current or former smokers with the incidence of gastric cancer by sex. We calculated the ratio of relative risk (RRR) with corresponding 95% CI based on sex-specific effect estimates for current or former smokers versus non-smokers on the risk of gastric cancer. We included 10 prospective studies with 3,381,345 participants in our analysis. Overall, the summary RRR (male to female) for gastric cancer risk in current smokers was significantly increased compared with non-smokers (RRR: 1.30; 95% CI: 1.05–1.63; P = 0.019). Furthermore, there was no significant sex difference for the association between former smokers and gastric cancer risk (RRR: 1.20; 95% CI: 0.92–1.55; P = 0.178). However, the result of sensitivity analysis indicated the pooled result was not stable, which was altered by excluding a nested case-control study (RRR: 1.31; 95% CI: 1.10–1.57; P = 0.002). This systematic review showed a potential sex difference association between current smokers and the risk of gastric cancer. The sex differential in smokers can give important clues for the etiology of gastric cancers and should be examined in further studies.

The brain is a common site for metastasis in non-small-cell lung cancer (NSCLC). This study was designed to evaluate the relationship between the mutational of the epidermal growth factor receptor (EGFR) and overall survival (OS) in NSCLC patients with brain metastases. Searches were performed in PubMed, EmBase, and the Cochrane Library to identify studies evaluating the association of EGFR mutation with OS in NSCLC patients through September 2017. 4373 NSCLC patients with brain metastases in 18 studies were involved. Mutated EGFR associated with significantly improved OS compared with wild type. Subgroup analyses suggested that this relationship persisted in studies conducted in Eastern, with retrospective design, with sample size ≥500, mean age of patients ≥65.0 years, percentage male < 50.0%, percentage of patients receiving tyrosine kinase inhibitor ≥30.0%. Finally, although significant publication bias was observed using the Egger test, the results were not changed after adjustment using the trim and fill method. This meta-analysis suggests that EGFR mutation is an important predictive factor linked to improved OS for NSCLC patients with brain metastases. It can serve as a useful index in the prognostic assessment of NSCLC patients with brain metastases.

BACKGROUND: Due to mixed reports from smaller studies, we examined associations of race with mammographic breast density and evaluated racial differences in the determinants of breast density. METHODS: Participants included 37,839 women (23,166 non-Hispanic White, and 14,673 African American women) receiving screening mammograms at the Joanne Knight Breast Health Center at Washington University School of Medicine, St. Louis, Missouri from June 2010 to December 2015. Mammographic breast density was assessed using Breast Imaging Reporting and Data System (5th edition). To determine the association of race and participant characteristics with mammographic breast density, we used multivariable polytomous logistic regression models (reference group: almost entirely fatty). RESULTS: African American women had increased odds of extremely dense (adjusted odds ratio (AOR) = 1.31, 95% CI = 1.13–1.52) and reduced odds of heterogeneously dense breasts (AOR= 0.91, 95% CI = 0.84 – 0.99) compared to non-Hispanic White women. Altogether, race, parity and age at first birth, age, current body mass index (BMI), BMI at age 18, menarche, family history of breast cancer, oral contraceptive use, alcohol, and menopausal status explained 33% of the variation in mammographic breast density. Among African American and non-Hispanic White women these factors explained nearly 28.6% and 33.6% of the variation in mammographic density, respectively. Current BMI provided the greatest explanation of breast density (26.2% overall, 22.2% in African American, and 26.2% in non-Hispanic White women). CONCLUSIONS: The determinants of mammographic breast density were generally similar between African-American women and non-Hispanic white women. After adjustments for confounders, African Americans had higher likelihood of extremely dense breast but lower likelihood of heterogeneously dense breast. The greatest explanation of breast density was provided by BMI, regardless of race.

Mammographic breast density is a strong risk factor for breast cancer. We comprehensively investigated the associations of body mass index (BMI) change from ages 10, 18, and 30 to age at mammogram with mammographic breast density in postmenopausal women. We used multivariable linear regression models, adjusted for confounders, to investigate the associations of BMI change with volumetric percent density, dense volume, and nondense volume, assessed using Volpara in 367 women. At the time of mammogram, the mean age was 57.9 years. Compared with women who had a BMI gain of 0.1–5 kg/m² from age 10, women who had a BMI gain of 5.1–10 kg/m² had a 24.4% decrease [95% confidence interval (CI), 6.0%–39.2%] in volumetric percent density; women who had a BMI gain of 10.1–15 kg/m² had a 46.1% decrease (95% CI, 33.0%–56.7%) in volumetric percent density; and women who had a BMI gain of >15 kg/m² had a 56.5% decrease (95% CI, 46.0%–65.0%) in volumetric percent density. Similar, but slightly attenuated associations were observed for BMI gain from ages 18 and 30 to age at mammogram and volumetric percent density. BMI gain over the life course was positively associated with nondense volume, but not dense volume. We observed strong associations between BMI change over the life course and mammographic breast density. The inverse associations between early-life adiposity change and volumetric percent density suggest that childhood adiposity may confer long-term protection against postmenopausal breast cancer via its effect of mammographic breast density.