Reproductive factors,hormone use and gastric cancer risk: The Singapore Chinese Health Study

Gastric cancer incidence varies greatly worldwide, but is consistently twice as high in men than in women. The hormone‐related factors hypothesized to be associated with lower risk of gastric cancer in women have not been fully explored in populations with a high background risk of gastric cancer. The Singapore Chinese Health Study (SCHS) is a prospective cohort study in which 34,022 of the participants enrolled between 1993 and 1998 were women between 45 and 74 years of age. Information on reproductive histories, hormone replacement therapy (HRT) and oral contraceptive (OC) use was collected through in‐person interviews at baseline. As of December 31, 2013, 269 incident gastric cancer cases were identified. Multivariable‐adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to evaluate gastric cancer risk associations. Older age at natural menopause (≥55 versus <45 years: HR = 0.50, 95% CI: 0.25–0.99), type of menopause (other versus natural: HR = 0.48, 95% CI: 0.27–0.87) and greater years of menstrual cycling (fourth versus first quartile: HR = 0.67, 95% CI: 0.46–0.96) were associated with a decreased risk of gastric cancer. Ever use of OCs and HRT was also associated with reduced risk of gastric cancer; the multivariable‐adjusted HRs (95% CIs) were 0.40 (0.17–0.90) for use of HRT >3 years and 0.67 (0.47–0.94) for ever use of OCs, compared with never use. Reproductive factors associated with a longer window of fertility and the use of exogenous hormones were shown to reduce gastric cancer development in a cohort of Chinese women with a high background risk of gastric cancer.     

Lung cancer risk by geologic coal deposits: A case–control study of female never-smokers from Xuanwei and Fuyuan,China

Coal types vary around the world because of geochemical differences in their source deposits; however, the influence of coal emissions from different deposits on human health remains unexplored. To address this issue, we conducted the first study of the relationship between coal use from various deposits and lung cancer risk in Xuanwei and Fuyuan, counties in China where lung cancer rates are among the highest in the world among female never-smokers due to use of bituminous (“smoky”) coal for heating and cooking. We conducted a population-based case–control study of 1031 lung cancer cases and 493 controls among never-smoking women in Xuanwei and Fuyuan. Logistic regression models were used to estimate associations between coal use from various deposits across the lifecourse and lung cancer risk. There was substantial heterogeneity in risks by coal deposit (p = 7.8E-05). Compared to non-smoky coal users, risks by smoky coal deposit ranged from OR = 7.49 (95% CI: 3.43–16.38) to OR = 33.40 (95% CI: 13.07–85.34). Further, women born into homes that used smoky coal and subsequently changed to non-smoky coal had a higher risk (OR = 10.83 (95% CI: 4.61–25.46)) than women born into homes that used non-smoky coal and changed to smoky coal (OR = 4.74 (95% CI: 2.03–11.04, p_difference = 0.04)). Our study demonstrates that various sources of coal have considerably different impact on lung cancer in this population and suggests that early-life exposure to carcinogenic emissions may exert substantial influence on health risks later in life. These factors should be considered when evaluating the health risks posed by exposure to coal combustion emissions.     

The impact of smoking on survival in renal cell carcinoma: a systematic review and meta-analysis

Epidemiological evidence suggests that cigarette smoking is the best-established risk factor for renal cell cancer (RCC). However, the effect of smoking on survival of RCC patients remains debated. We therefore conducted a meta-analysis to investigate the impact of smoking status on overall mortality (OM), disease-specific mortality (DSM), overall survival (OS), cancer-specific survival (CSS), and progression-free survival (PFS) in patients with RCC. We searched Medline, Embase, and the Cochrane Central Search Library for published studies that analyzed the effect of smoking on survival or mortality of RCC. We selected 14 articles according to predefined inclusion criteria. The smoking status was categorized into never smokers and ever smokers (former smokers and/or current smokers). Summary hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated with a fixed or random effects model. Overall, 14 studies including 343,993 RCC cases were accepted for meta-analysis. Ever smoking was significantly correlated with OM (HR 1.30, 95 % CI 1.07–1.58), while no associated with poorer DSM (HR 1.23, 95 % CI 0.96–1.57). Further analysis found current (HR 1.57, 95 % CI 1.20–2.06) but not former smoking (HR 1.14, 95 % CI 0.79–1.63) was associated with a significantly increased risk of OM. Meanwhile, current smoking was associated with poorer DSM (HR 1.50, 95 % CI 1.10–2.05) in subgroup analysis. Ever smoking was significantly associated with poorer OS (HR 1.45; 95 % CI 1.00–2.09) and poorer CSS (HR 1.01; 95 % CI 1.00–1.02), compared with never smokers. Current smoking was associated with poorer PFS (HR 2.94, 95 % CI 1.89–4.58). This review provides preliminary evidence that current smoking in a patient with RCC is associated with poorer survival, demonstrating active smoking to be an independent risk for prognosis of RCC. Smoking cessation should be recommended for RCC patients.     

Hormonal factors and pancreatic cancer risk in women: The Malmö Diet and Cancer Study

The incidence of pancreatic cancer is leveling between sexes. Smoking, high age and heredity are established risk factors, but evidence regarding the influence of hormonal factors is unclear. In this study, we investigated the associations of reproductive factors, use of oral contraceptives (OC) and hormone replacement therapy (HRT) with pancreatic cancer risk in the Malmö Diet and Cancer Study, a prospective, population‐based cohort encompassing 17,035 women. Up until 31 December 2015, 110 women were identified with incident pancreatic cancer through the Swedish Cancer Registry. Higher age at menarche was significantly associated with pancreatic cancer risk (age‐adjusted [hazard ratio] HR = 1.17; 95% confidence interval [CI] 1.04–1.32, and fully adjusted HR = 1.17; 95% CI 1.04–1.32). Ever use of OC was not significantly associated with pancreatic cancer risk but ever use of HRT was significantly associated with a decreased risk of pancreatic cancer (age‐adjusted HR = 0.47, 95% CI 0.23–0.97, and fully adjusted HR = 0.48, 95% CI 0.23–1.00), in particular use of estrogen‐only regimen (age‐adjusted HR = 0.21; 95% CI 0.05–0.87 and fully adjusted HR = 0.22; 95% CI 0.05–0.90). Age at menopause or first childbirth, parity and breastfeeding history were not significantly associated with pancreatic cancer risk. Collectively, these findings suggest a protective role of female hormones against pancreatic cancer. Further studies are needed, and potential modifying genetic factors and indirect hazardous effects of smoking should also be considered.     

Reproductive and hormonal factors and risk of lung cancer in women: a prospective cohort study

Several lines of evidence suggest that endocrine factors may play a role in the development of lung cancer, but the evidence is limited and inconsistent. We investigated the association of reproductive and hormonal factors with risk of lung cancer in the National Breast Screening Study, which included 89,835 Canadian women aged 40-59 years at recruitment between 1980 and 1985. Linkages to national cancer and mortality databases provided data on cancer incidence and deaths from all causes, respectively, with follow-up ending between 1998 and 2000. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between hormonal factors and lung cancer. During a mean of 16.4 years of follow-up, we observed 750 incident lung cancer cases. After adjustment for covariates, parous women were not at increased risk of lung cancer (HR = 1.18, 95% CI 0.94-1.47) relative to nulliparous women; however, there was a modest increase in risk with increasing parity, reaching a HR of 1.42, 95% CI 1.06-1.88 in women who had 5 or more live births (p for trend 0.02). Among parous women, age at first live birth was inversely associated with risk. Women who had their first live birth at age 30 or older were at reduced risk relative to women who had their first live birth below age 23 (HR 0.68, 95% CI 0.50-0.93, p for trend 0.004). These associations did not differ by age at enrollment (40-49 vs. 50-59 years old), but were somewhat strengthened when attention was restricted to never smokers. Ever use of exogenous hormones showed little association with lung cancer risk; however, long-term users of hormone replacement therapy were at slightly increased risk. Our results add to the limited existing evidence that certain reproductive and hormonal factors may be associated with lung cancer risk in women.     

Hypertension,use of antihypertensive medications,and risk of epithelial ovarian cancer

Few studies have examined the associations of hypertension and antihypertensive medications with ovarian cancer. In particular, beta‐blockers, one of the most commonly prescribed medications to treat hypertension, may reduce ovarian cancer risk by inhibiting beta‐adrenergic signaling. We prospectively followed 90,384 women in the Nurses' Health Study (NHS) between 1988–2012 and 113,121 NHSII participants between 1989–2011. Hypertension and use of antihypertensive medications were self‐reported biennially. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). We documented 948 ovarian cancer cases during follow‐up. Similar results were observed in the two cohorts. While hypertension was not associated with ovarian cancer risk (Pooled HR = 1.01; 95% CI = 0.88, 1.16), current use of any antihypertensive medication was associated with slightly increased risk compared to never users (Pooled HR = 1.18; 95% CI: 1.02, 1.37). This increased risk was primarily due to use of thiazide diuretics (Pooled HR = 1.37; 95% CI: 1.13, 1.68). No associations were observed for beta‐blockers or angiotensin‐converting‐enzyme inhibitors. Calcium channel blockers (CCBs) were associated with suggestively reduced risk (NHS HR = 0.73; 95% CI: 0.53, 1.01), after adjusting for all antihypertensive medications. Associations were similar among hypertensive women and stronger for longer use of thiazide diuretics and CCBs. In conclusion, our results provided no evidence that beta‐blockers were associated with reduced ovarian cancer risk. In contrast, we observed an increased risk for use of thiazide diuretics that should be confirmed in other studies.     

Use of oral contraceptives,intrauterine devices and tubal sterilization and cancer risk in a large prospective study,from 1996 to 2006

The association of contraceptive methods, including oral contraceptives (OC), intrauterine devices (IUD) and tubal sterilization (TS), with overall and site‐specific cancer were prospectively investigated in a cohort of 66,661 Chinese women in Shanghai, 76.7% of whom used contraception. During a median follow‐up time of 7.5 years, 2,250 women were diagnosed with cancer. Ever‐use of any contraceptive method was not associated with overall cancer risk [adjusted hazard ratio (HR_adj) = 1.02, 95% CI, 0.92–1.12]. Use of any contraceptive method was associated with increased risk of rectal cancer (HR_adj = 1.68, 95% CI, 1.08–2.62) and reduced risk of thyroid cancer (HR_adj = 0.63, 95% CI, 0.38–1.04). Risk of gallbladder cancer increased with ever use of OC (HR_adj = 2.38, 95% CI, 1.26–4.49). IUD use was associated with a possible reduced risk of thyroid cancer (HR_adj = 0.64, 95% CI, 0.38–1.07). Longer duration of IUD use decreased risk for breast, thyroid and lung cancers. Ever having a TS was associated with increased uterine body cancer (HR_adj = 2.50, 95% CI, 1.47–4.25) and decreased risk of stomach cancer (HR_adj = 0.59, 95% CI, 0.39–0.91). We did not find any contraceptive method to be related to the risk of ovarian cancer but the analyses were based on few events. Although chance findings are a likely explanation for some of the associations found in our study, these findings suggest that various contraceptive methods or reproductive patterns may play a role in the etiology of cancer. © 2008 Wiley‐Liss, Inc.     

Use of hormone therapy and risk of breast cancer detected at screening and between mammographic screens

Postmenopausal hormone therapy (HT) is associated with increased risk of breast cancer, but in women undergoing breast cancer screening it is not clear whether use of HT is associated with increased risk of breast cancer detected at screening or between screens (interval cancer). Further, it is unclear whether the use of the HTs that have been common in Scandinavia is associated with higher risk of breast cancer than the HTs used in other countries. Our study was based on data from 296,651 women aged 50-69 years, who participated in the Norwegian Breast Cancer Screening Program during 1995-2004. After a mean enrollment time of 3.8 years, 1,512 women were diagnosed with invasive screen detected breast cancer, and 814 with invasive interval breast cancer. Cox regression models were used to estimate hazard ratios (HRs) of breast cancer associated with HT use, after adjusting for confounders. Ever users of HT had a 58% increased risk of breast cancer, compared to never users. The HRs associated with HT use were 1.45 (95% confidence interval (CI) = 1.29-1.63) for screen detected and 1.89 (95% CI = 1.61-2.23) for interval cancer. The difference between screen detected and interval cancer was statistically significant (p = 0.011). The HR of breast cancer increased with duration of HT use, but significantly more so for interval than for screen detected cancer (use of HT for 5 or more years compared to never use; HR = 2.91, 95% CI = 2.10-4.04 and HR = 1.94, 95% CI = 1.51-2.50, respectively; p = 0.002). The population attributable fraction of breast cancer due to HT use was 19.8% overall. Ever users of HT tended to develop a cancer of lower grade. No other differences in histological tumor characteristics were observed between ever and never users of HT among screen detected or interval cancers. The estimated risks of either breast cancer overall with HT use are higher in Norway than reported in similar studies from the U.S. HT-use is a stronger risk factor for interval cancer than for screen detected cancer. The increased risk of interval cancer, which may partly be due to decreased sensitivity of mammograms in HT users, remains a challenge in breast cancer screening programs.     

X射线损伤修复交叉互补基因1多态性与非吸烟女性肺癌易感性的关系

目的探讨X射线损伤修复交叉互补基因1（XRCCl）单核苷酸多态性与非吸烟女性肺癌易感性的关系。方法采用以医院患者为基础的病例一对照研究方法,非吸烟女性肺癌患者50例,非癌对照50例。以聚合酶链反应一限制性片段长度多态性（PCR—RFLP）方法检测XRCC1基因Arg399Gln多态性,计算各基因型的比值比（OR）,并探讨烹饪油烟暴露史与多态基因型交互作用对肺癌患癌风险的影响。结果肺癌组与对照组XRCC1 Arg399Gln多态基因型分布差异无统计学意义（P〉0．05）,而腺癌组基因型分布与对照组差异有统计学意义（P〈0．05）。相对于399Arg／Arg基因型,携带至少1个Gin等位基因的个体患肺腺癌的调整OR值为2．19（95％CI为0．73～6．61）,而XRCC1 399Gin／Gin基因型携带者的调整OR值为14．12（95％CI为2、14～92．95）。携带至少1个399Gln等位基因的烹饪油烟暴露者患肺腺癌的风险明显升高,调整OR值为6．29（95％c,为1．99～19、85）。结论XRCC1基因Arg399Gln多态可能是非吸烟女性肺腺癌的遗传易感因素,399Gln等位基因与烹饪油烟交互作用,可提高非吸烟女性肺腺癌的发病风险。     

E7080, a novel inhibitor that targets multiple kinases, has potent antitumor activities against stem cell factor producing human small cell lung cancer H146, based on angiogenesis inhibition

Flavonoids, which are found in certain plant foods, are thought to lower cancer risk through their antioxidant, antiestrogenic and antiproliferative properties. We examined the association of intake of total flavonoids and 7 flavonoid subclasses with risk of lung, colorectal, breast, pancreatic and upper aerodigestive cancer among women in a large prospective cohort study. Study participants were 34,708 postmenopausal women in the Iowa Women's Health Study who completed a food frequency questionnaire and were followed for cancer occurrence from 1986 through 2004. Flavonoid intake was estimated from 3 databases developed by the USDA Nutrient Data Laboratory (NDL). Hazard ratios (HR) for cancer risk were calculated across total flavonoid and flavonoid subclass intake categories. Interactions between smoking history and flavonoid intake were also examined. After multivariable adjustment, lung cancer incidence was inversely associated with intakes of flavanones (HR = 0.68; 95% CI: 0.53-0.86, all results highest vs. lowest quintile) and proanthocyanidins (HR = 0.75; 95% CI: 0.57-0.97). Among current and past smokers, those with intakes in the highest quintile for flavanones (HR = 0.66; 95% CI: 0.50-0.86), and proanthocyanidins (HR = 0.66; 95% CI; 0.49-0.89) had significantly lower lung cancer incidence than those in the lowest quintile. Similar associations were not seen in never smokers. Isoflavone intake was inversely associated with overall cancer incidence (HR = 0.93, 95% CI: 0.86-1.00). This study provides further support for a beneficial effect of flavonoid intake on lung cancer risk, especially among current and past smokers.     

Smoky coal,tobacco smoking,and lung cancer risk in Xuanwei,China

Objectives

Lung cancer rates in Xuanwei are the highest in China. In-home use of smoky coal has been associated with lung cancer risk, and the association of smoking and lung cancer risk strengthened after stove improvement. Here, we explored the differential association of tobacco use and lung cancer risk by the intensity, duration, and type of coal used.

Materials and methods

We conducted a population-based case-control study of 260 male lung cancer cases and 260 age-matched male controls. Odds ratios (OR) and 95% confidence interval (CI) for tobacco use was calculated by conditional logistic regression.

Results

Use of smoky coal was significantly associated with an increased risk of lung cancer, and tobacco use was weakly and non-significantly associated with lung cancer risk. When the association was assessed by coal use, the cigarette-lung cancer risk association was null in hazardous coal users and elevated in less hazardous smoky coal users and non-smoky coal users. The risk of lung cancer per cigarette per day decreased as annual use of coal increased (>0–3 tons: OR: 1.09; 95% CI: 1.03–1.17; >3 tons: OR: 0.99; 95% CI: 0.95–1.03). Among more hazardous coal users, attenuation occured at even low levels of usage (>0–3 tons: OR: 1.02; 95% CI: 0.91–1.14; >3 tons: OR: 0.94; 95% CI: 0.97–1.03).

Conclusion

We found evidence that smoky coal attenuated the tobacco and lung cancer risk association in males that lived in Xuanwei, particularly among users of hazardous coal where even low levels of smoky coal attenuated the association. Our results suggest that the adverse effects of tobacco may become more apparent as China's population continues to switch to cleaner fuels for the home, underscoring the urgent need for smoking cessation in China and elsewhere.     

Household air pollution and risk of incident lung cancer in urban China: A prospective cohort study

Household air pollution (HAP) is associated with the development of lung cancer, yet few studies investigated the exposure patterns and joint associations with tobacco smoking. In our study, we included 224 189 urban participants from China Kadoorie Biobank (CKB), 3288 of which diagnosed with lung cancer during the follow-up. Exposure to four HAP sources (solid fuels for cooking/heating/stove and environmental tobacco smoke exposure) was assessed at baseline. Distinct HAP patterns and their associations with lung cancer were examined through latent class analysis (LCA) and multivariable Cox regression. A total of 76.1% of the participants reported regular cooking and 52.2% reported winter heating, of which 9% and 24.7% used solid fuels, respectively. Solid fuel heating increased lung cancer risk (Hazards ratio [HR]: 1.25, 95% confidence interval [CI]: 1.08-1.46). LCA identified three HAP patterns; the “clean fuel cooking and solid fuel heating” pattern significantly increased lung cancer risk (HR: 1.25, 95% CI: 1.10-1.41), compared to low HAP pattern. An additive interaction was observed between heavy smoking and “clean fuel cooking and solid fuel heating” (relative excess risk [RERI]: 1.32, 95% CI: 0.29-2.47, attributable proportion [AP]: 0.23, 95% CI: 0.06-0.36). Cases resulting from solid fuel account for ~4% of total cases (population attribute fraction [PAF]_overall: 4.31%, 95% CI: 2.16%-6.47%, PAF_{ever smokers}: 4.38%, 95% CI: 1.54%-7.23%). Our results suggest that in urban China, solid fuel heating increased the risk of lung cancer, particularly among heavy smokers. The whole population could benefit from cleaner indoor air quality by reducing using solid fuels, especially smokers.     

Contraceptive methods and ovarian cancer risk among Chinese women: A report from the Shanghai Women's Health Study

Oral contraceptive use is associated with reduced ovarian cancer risk; however, associations with other contraceptive methods, such as intrauterine device (IUD) and tubal ligation, are less clear. Women in China differ from western women in regard to mechanisms and duration of use of contraception. This study was undertaken to evaluate associations between contraceptive methods and ovarian cancer risk using data from the prospective Shanghai Women's Health Study. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by Cox proportional hazards regression. A total of 174 epithelial ovarian cancer cases were found to occur among 70,259 women who were followed‐up for a total of 888,258 person‐years. The majority of women had ever used any contraception (77.0%), including IUD (55.6%), oral contraceptive (20.4%), tubal ligation (14.7%) or contraceptive shots (2.6%). Ever use of any contraception was associated with a nonsignificant reduction in ovarian cancer risk (HR: 0.86, 95% CI: 0.60–1.24). Longer duration of IUD use was associated with lower ovarian cancer risk (p‐value for trend = 0.04). Compared with never users, women with durations of IUD use longer than the median (20 years) were 38% less likely to develop ovarian cancer (HR: 0.62, 95% CI: 0.40–0.97). Based on the high prevalence and long duration of IUD use among Chinese women, we estimate a preventive fraction of 9.3%, corresponding to approximately 16 ovarian cancer cases. High prevalence of long‐term IUD use may, therefore, contribute to the low incidence of ovarian cancer observed in China.     

Prediagnosis and postdiagnosis smoking and survival following diagnosis with ovarian cancer

Little is known about the influence of prediagnosis and postdiagnosis smoking and smoking cessation on ovarian cancer survival. We investigated this relationship in two prospective cohort studies, the Nurses’ Health Study (NHS) and NHSII. Analyses included 1,279 women with confirmed invasive, Stage I–III epithelial ovarian cancer. We used Cox proportional hazards regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for ovarian cancer-specific mortality by smoking status, adjusting for age and year of diagnosis, tumor stage, histologic subtype, body mass index and nonsteroidal anti-inflammatory use (postdiagnosis models only). When examining prediagnosis smoking status (assessed a median of 12 months before diagnosis), risk of death was significantly increased for former smokers (HR = 1.19, 95% CI: 1.02–1.39), and suggestively for current smokers (HR = 1.21, 95% CI: 0.96–1.51) vs. never smokers. Longer smoking duration (≥20 years vs. never, HR = 1.23, 95% CI: 1.05–1.45) and higher pack-years (≥20 pack-years vs. never, HR = 1.28, 95% CI: 1.07–1.52) were also associated with worse outcome. With respect to postdiagnosis exposure, women who smoked ≥15 cigarettes per day after diagnosis (assessed a median of 11 months after diagnosis) had increased mortality compared to never smokers (HR = 2.34, 95% CI: 1.63–3.37). Those who continued smoking after diagnosis had 40% higher mortality (HR = 1.40, 95% CI: 1.05–1.87) compared to never smokers. Overall, our results suggest both prediagnosis and postdiagnosis smoking are associated with worse ovarian cancer outcomes.     

Portable stove use is associated with lower lung cancer mortality risk in lifetime smoky coal users

Domestic fuel combustion from cooking and heating, to which about 3 billion people worldwide are exposed, is associated with increased lung cancer risk. Lung cancer incidence in Xuanwei is the highest in China, and the attributable risk of lung cancer from unvented smoky coal burning is greater than 90%. To evaluate any lung cancer mortality reduction after changing from unvented stoves to portable stoves, we used lifetime smoky coal users in a retrospective cohort of all farmers born during 1917–1951 and residing in Xuanwei in 1976. Of the 42 422 enrolled farmers, 4054 lifetime smoky coal users changed to portable stoves, 4364 did not change, and 1074 died of lung cancer. Lung cancer morality associated with stove change was assessed by product-limit survival curves and multivariate Cox regression models. Both men (P<0.0001) and women (P<0.0001) who changed to portable stoves had a significantly increased probability of survival compared with those who did not change. Portable stoves were associated with decreased risk of lung cancer mortality in male participants (hazard ratio (HR)=0.62, 95% confidence interval (CI)=0.46–0.82) and female participants (HR=0.41, 95% CI=0.29–0.57). Portable stove use is associated with reduced lung cancer mortality risk, highlighting a cost-effective intervention that could substantially benefit health in developing countries.     

Cooking oil fumes and risk of lung cancer in women in rural Gansu, China.

Cooking oil fumes have been suggested to increase the risk of lung cancer in Chinese women by exposing them to mutagenic substances. We investigated the association between lung cancer and locally made rapeseed and linseed oils in a population-based case-control study in Gansu Province, China. Two hundred and thirty-three incident, female lung cancer cases diagnosed from 1994-98 were identified. A control group of 459 women was selected from census lists and were frequency matched on age and prefecture. Interviewers obtained information on cooking practices and cooking oil use. The odds ratio (OR) for lung cancer associated with ever-use of rapeseed oil, alone or in combination with linseed oil, was 1.67 (95% CI 1.0-2.5), compared to use of linseed oil alone. ORs for stir-frying with either linseed or rapeseed oil 15-29, 30 and > or =31 times per month were 1.96,1.73, and 2.24, respectively (trend, P=0.03), relative to a lower frequency of stir-frying. Lung cancer risks also increased with total number of years cooking (trend, P<0.09). Women exposed to cooking fumes from rapeseed oil appeared to be at increased risk of lung cancer, and there was some evidence that fumes from linseed oil may have also contributed to the risk.     

Vitamin E intake and the lung cancer risk among female nonsmokers: A report from the Shanghai Women's Health Study

Vitamin E includes several tocopherol isoforms, which may reduce lung cancer risk, but past studies evaluating the association between vitamin E intake and lung cancer risk were inconsistent. We prospectively investigated the associations between tocopherol intake from diet and from supplements with lung cancer risk among 72,829 Chinese female nonsmokers aged 40–70 years and participating in the Shanghai Women's Health Study (SWHS). Dietary and supplement tocopherol exposure was assessed by a validated food‐frequency questionnaire at baseline and reassessed for change in intake during follow‐up. Cox proportional hazards models with time‐dependent covariates were used to calculate multivariate‐adjusted hazard ratios (HRs) and 95% confidence interval (CIs) for lung cancer. After 12.02 years of follow‐up, 481 women were diagnosed with lung cancer. Total dietary tocopherol was inversely associated with lung cancer risk among women meeting dietary guidelines for adequate intake (AI) of tocopherol (14 mg/day or more: HR: 0.78; 95% CI 0.60–0.99; compared with the category less than AI). The protective association between dietary tocopherol intake and lung cancer was restricted to women exposed to side‐stream smoke in the home and workplace [HR = 0.53 (0.29–0.97), p‐trend = 0.04]. In contrast, vitamin E supplement use was associated with increased lung cancer risk (HR: 1.33; 95% CI: 1.01–1.73), more so for lung adenocarcinoma risk (HR: 1.79; 95% CI: 1.23–2.60). In summary, dietary tocopherol intake may reduce the risk of lung cancer among female nonsmokers; however, supplements may increase lung adenocarcinoma risk and requires further investigation.     

Snus use,smoking and survival among prostate cancer patients

Smoking is associated with prostate cancer mortality. The Scandinavian smokeless tobacco product snus is a source of nicotine but not the combustion products of smoke and has not been studied with respect to prostate cancer survival. The study is nested among 9,582 men with incident prostate cancer within a prospective cohort of 336,381 Swedish construction workers. Information on tobacco use was collected at study entry between 1971 and 1992, and categorized into (i) never users of any tobacco, (ii) exclusive snus: ever users of snus only, (iii) exclusive smokers: ever smokers (cigarette, cigar and/or pipe) only and (iv) ever users of both snus and smoking. Hazard ratios for prostate cancer‐specific and total mortality for smoking and snus use based on Cox proportional hazards models adjusted for age, calendar period at diagnosis and body mass index at baseline. During 36 years of follow‐up, 4,758 patients died—2,489 due to prostate cancer. Compared to never users of tobacco, exclusive smokers were at increased risk of prostate cancer mortality (HR 1.15, 95% CI: 1.05–1.27) and total mortality (HR 1.17, 95% CI: 1.09–1.26). Exclusive snus users also had increased risks for prostate cancer mortality (HR 1.24, 95% CI: 1.03–1.49) and total mortality (HR 1.19, 95% CI: 1.04–1.37). Among men diagnosed with nonmetastatic disease, the HR for prostate cancer death among exclusive snus users was 3.17 (95% CI: 1.66–6.06). The study is limited by a single assessment of tobacco use prior to diagnosis. Snus use was associated with increased risks of prostate cancer and total mortality among prostate cancer patients. This suggests that tobacco‐related components such as nicotine or tobacco‐specific carcinogens may promote cancer progression independent of tobacco's combustion products.     

Metformin and other anti-diabetic medication use and breast cancer incidence in the Nurses' Health Studies

We aimed to examine the association between the use of metformin and other anti-diabetic medications and breast cancer incidence within two large prospective cohort studies. We followed 185,181 women who participated in the Nurses' Health Study (NHS; 1994–2016) and the NHSII (1995–2017), with baseline corresponding to the date metformin was approved for type 2 diabetes (T2D) treatment in the US Information on T2D diagnosis, anti-diabetes medications, and other covariates was self-reported at baseline and repeatedly assessed by follow-up questionnaires every 2 years. Breast cancer cases were self-reported and confirmed by medical record review. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between medication use and breast cancer were estimated using Cox proportional hazards regression models, adjusting for breast cancer risk factors. During 3,324,881 person-years of follow-up, we ascertained 9,192 incident invasive breast cancer cases, of which 451 were among women with T2D. Compared with women without T2D (n = 169,263), neither metformin use (HR = 0.97; 95% CI = 0.81–1.15) nor other anti-diabetic medications use (HR = 1.11; 95% CI = 0.90–1.36) associated with significantly lower breast cancer incidence. Among women with T2D (n = 15,918), compared with metformin never users, metformin ever use was not significantly inversely associated with breast cancer (HR = 0.92; 95% CI = 0.74–1.15). Although we observed that past use of metformin was inversely associated with breast cancer in the T2D population (HR = 0.67; 95% CI = 0.48–0.94), current use (HR = 1.01; 95% CI = 0.80–1.27) and longer duration of metformin use were not associated with breast cancer (each 2-year interval: HR = 1.01; 95% CI = 0.95–1.07). Overall, metformin use was not associated with the risk of developing breast cancer among the overall cohort population or among women with T2D.     

Tuberculosis and subsequent risk of lung cancer in Xuanwei,China

Tobacco and indoor air pollution from smoky coal are major causes of lung cancer in rural Xuanwei County, China. Tuberculosis has been suggested to increase lung cancer risk, but data from prior studies are limited. We conducted an analysis of data from a retrospective cohort study of 42,422 farmers in Xuanwei. In 1992, interviewers administered a standardized questionnaire that included lifetime medical history, including tuberculosis. Subjects were followed from 1976, with deaths from lung cancer ascertained through 1996. We used proportional hazards regression to assess the association between tuberculosis and subsequent lung cancer mortality. Tuberculosis was reported by 246 subjects (0.6%), and 2,459 (5.8%) died from lung cancer during follow‐up. Lung cancer mortality was substantially higher in subjects with tuberculosis than in those without (25 vs. 3.1 per 1,000 person‐years). The association was especially pronounced in the first 5 years after tuberculosis diagnosis (hazard ratios [HRs] ranging 6.7–13) but remained strong 5–9.9 years (HR 3.4, 95% CI 1.3–9.1) and 10+ years (HR 3.0, 95% CI 1.3–7.3) after tuberculosis. These associations were similar among men and women and among smoky coal users (70.5% of subjects). Adjustment for demographic characteristics, lung disease and tobacco use did not affect results. In Xuanwei, China, tuberculosis is an important risk factor for lung cancer. The increased lung cancer risk, persisting years after a tuberculosis diagnosis, could reflect the effects of chronic pulmonary inflammation and scarring arising from tuberculosis. Published 2008 Wiley‐Liss, Inc.