Risk factors for lung cancer in Singapore Chinese, a population with high female incidence rates

Opium, phencyclidine, and crack cocaine smoking associations with lung and upper aerodigestive tract cancers: exploratory findings from a case-control study in Los Angeles County

Background: Illicit drug use has become a global epidemic, yet it is unclear if drug smoking increases the risk of tobacco-related cancers.Objectives: We aimed to evaluate hypothesized associations between smoking three drugs - opium, phencyclidine (PCP) and crack cocaine and lung and upper aerodigestive tract (UADT) cancers.Methods: A population-based case-control study with 611 lung cancer cases (50% male), 601 UADT cancers cases (76% male), and 1,040 controls (60% male) was conducted in Los Angeles County (1999-2004). Epidemiologic data including drug smoking histories were collected in face-to-face interviews. Associations were estimated with logistic regressions.Results: Adjusting for potential confounders, ever vs. never crack smoking was positively associated with UADT cancers (aOR = 1.56, 95% CI: 1.05, 2.33), and a dose-response relationship was observed for lifetime smoking frequency (p for trend = .024). Heavy (> median) vs. never crack smoking was associated with UADT cancers (aOR = 1.81, 95% CI: 1.07, 3.08) and lung cancer (aOR = 1.58, 95% CI: 0.88, 2.83). A positive association was also observed between heavy PCP smoking and UADT cancers (aOR = 2.29, 95% CI: 0.91, 5.79). Little or no associations were found between opium smoking and lung cancer or UADT cancers.Conclusion: The positive associations between illicit drug use and lung and/or UADT cancers suggest that smoking these drugs may increase the risk of tobacco-related cancers. Despite the low frequency of drug smoking and possible residual confounding, our findings may provide additional insights on the development of lung and UADT cancers.

The carcinogenicity of opium consumption: a systematic review and meta-analysis

The carcinogenicity of opium consumption was recently evaluated by a Working Group convened by the International Agency for Research on Cancer (IARC). We supplement the recent IARC evaluation by conducting an extended systematic review as well as a quantitative meta-analytic assessment of the role of opium consumption and risk for selected cancers, evaluating in detail various aspects of study quality on meta-analytic findings. We searched the published literature to identify all relevant studies on opium consumption and risk of selected cancers in humans through 31 October, 2022. Meta-relative risks (mRRs) and associated 95% confidence intervals (CIs) were estimated using random-effects models for studies of cancer of the urinary bladder, larynx, lung, oesophagus, pancreas, and stomach. Heterogeneity among studies was assessed using the I2 statistic. We assessed study quality and conducted sensitivity analyses to evaluate the impact of potential reverse causation, protopathic bias, selection bias, information bias, and confounding. In total, 2 prospective cohort studies and 33 case-control studies were included. The overall pooled mRR estimated for 'ever or regular' versus 'never' use of opium ranged from 1.50 (95% CI 1.13-1.99, I2 = 0%, 6 studies) for oesophageal cancer to 7.97 (95% CI 4.79-13.3, I2 = 62%, 7 studies) for laryngeal cancer. Analyses of cumulative opium exposure suggested greater risk of cancer associated with higher opium consumption. Findings were robust in sensitivity analyses excluding studies prone to potential methodological sources of biases and confounding. Findings support an adverse association between opium consumption and cancers of the urinary bladder, larynx, lung, oesophagus, pancreas and stomach.

Opium use and risk of lung cancer: A multicenter case-control study in Iran

Opium use was recently classified as a human carcinogen for lung cancer by the International Agency for Research on Cancer. We conducted a large, multicenter case-control study evaluating the association between opium use and the risk of lung cancer. We recruited 627 cases and 3477 controls from May 2017 to July 2020. We used unconditional logistic regression analyses to estimate the odds ratios (OR) and 95% confidence intervals (CI) and measured the association between opium use and the risk of lung cancer. The ORs were adjusted for the residential place, age, gender, socioeconomic status, cigarettes, and water pipe smoking. We found a 3.6-fold risk of lung cancer for regular opium users compared to never users (95% CI: 2.9, 4.6). There was a strong dose-response association between a cumulative count of opium use and lung cancer risk. The OR for regular opium use was higher for small cell carcinoma than in other histology (8.3, 95% CI: 4.8, 14.4). The OR of developing lung cancer among opium users was higher in females (7.4, 95% CI: 3.8, 14.5) than in males (3.3, 95% CI: 2.6, 4.2). The OR for users of both opium and tobacco was 13.4 (95% CI: 10.2, 17.7) compared to nonusers of anything. The risk of developing lung cancer is higher in regular opium users, and these results strengthen the conclusions on the carcinogenicity of opium. The association is stronger for small cell carcinoma cases than in other histology.

Association between long-term opioid use and cancer risk in patients with chronic pain: a propensity score-matched cohort study

BACKGROUND

Whether long-term opioid use is an independent risk factor for cancer progression remains unclear. Therefore, we conducted a propensity score-matched population-based cohort study to compare cancer incidence between patients with chronic pain with and without opioid use.

METHODS

Data from January 2008 to December 2019 were obtained from the Taiwan National Health Insurance Research Database. Patients were categorised into two groups according to the presence or absence of opioid use, and matched at a 4:1 ratio. The incidence rate ratios for specific cancers were determined.

RESULTS

Propensity score-matching yielded 63 610 patients: 50 888 with opioid use (the opioid group) and 12 722 without (the non-opioid group). In a multivariate Cox regression analysis, the adjusted hazard ratio (95% confidence interval) for cancers in the opioid group compared with the non-opioid group was 2.66 (1.44-2.94; P<0.001). The incidence rate ratios (95% confidence interval) for lung, hepatocellular, colorectal, breast, prostate, head and neck, pancreatic, gastric, oesophageal, and ovarian cancers for the opioid group were 1.87 (1.41-2.43), 1.97 (1.56-2.50), 2.39 (1.87-3.03), 2.43 (1.75-3.33), 2.00 (1.35-3.03), 1.79 (1.14-2.86), 1.87 (1.13-2.12), 2.43 (1.52-3.85), 1.82 (0.92-3.70), and 2.33 (1.01-5.55), respectively.

CONCLUSION

There was an association between long-term opioid use and development of cancer in patients with chronic pain, which should be confirmed in future studies.

Opium Use and Cancer Risk: A Comprehensive Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

Epidemiological studies have reported inconsistent associations between opium use and cancer risk. We therefore conducted a systematic review and meta-analysis to investigate the relationship between opium use and cancer risk.

METHODS

We searched PubMed, Scopus, ISI Web of Knowledge, and Google Scholar until February 2021 and references of retrieved relevant articles for observational studies that reported the risk of cancer in relation to opium use. Random-effects models were used to calculate pooled effect sizes (ESs) as well as 95% confidence intervals (CIs) for the association between opium use and cancer risk by considering opium doses and types, duration of consumption, and routes of opium use.

RESULTS

In total, 21 observational articles, with a total sample size of 64,412 individuals and 6,658 cases of cancer, were included in this systematic review and meta-analysis. Ever opium users, compared with never opium users, had 3.53 times greater risk of overall cancer (pooled ES: 3.53, 95% CI: 2.60-4.79, P ≤ 0.01). This positive association was also seen for some individual types of cancers except for esophageal and colon cancers. Also, we found that higher opium doses and higher duration of consumption were associated with an increased risk of overall and individual types of cancer. However, the associations between opium doses and the risk of head and neck and larynx cancers were not significant. In terms of the routes of opium use, both opium ingestion and smoking were positively associated with the risk of cancer. Regarding opium types, we found that using teriak, but not shireh, could increase the risk of cancer.

CONCLUSIONS

Our findings showed that opium use, particularly in the form of teriak, is a risk factor for cancer.

The Adverse Impact of Incense Smoke on Human Health: From Mechanisms to Implications

Incense burning is a very popular activity in daily life among many parts all over the world. A growing body of both epidemiological and experimental evidences has reported the negative effects of incense use on human well-being, posing a potential threat at public significance. This work is a comprehensive review that covers the latest findings regarding the adverse impact of incense smoke on our health, providing a panoramic visualization ranging from mechanisms to implications. The toxicities of incense smoke come directly from its harmful constituents and deposition capacity in the body. Besides, reactive oxygen species-driven oxidative stress and associated inflammation seem to be plausible underlying mechanisms, eliciting various unfavorable responses. Although our current knowledge remains many gaps, this issue still has some important implications.

Opium Usage and Risk of Head and Neck Cancer: A Systematic Review and Meta-Analysis

INTRODUCTION

Opium is among the most used substance of abuse worldwide. More than 50 million opium users are there worldwide, majority of whom are in Asia. Opium usage have been reported to be associated with cancer. This study aimed to find the association between opium use or abuse and head and neck cancer.

METHODS

A systematic search was conducted in Medline, Scopus, Cochrane, and Google Scholar database for studies published from inception till 1st November 2019. Two authors independently reviewed the studies, did quality assessment, and extracted data in standardized data extraction form. Pooled estimate of OR for risk of head and neck cancer was calculated using random effects model using the method of DerSimonian and Laird, with the estimate of heterogeneity being taken from the inverse-variance model. Subgroup and sensitivity analysis were performed. The protocol was registered in PROSPERO (CRD42020156049).

RESULTS

Fourteen studies were included in data synthesis (11 case control studies and 3 cohort studies). Eleven case control studies were included in synthesizing the results for meta-analysis. Pooled odds ratio for risk of cancer among opium users for the 11-case control study was 3.85 (2.18-6.79). Heterogeneity was high (I-squared=92.0%, Tau-squared=0.88). There was no publication bias in the study. Subgroup analysis showed highest OR for pooled estimate for risk of laryngeal cancer (19.98 (11.04-36.15)).

CONCLUSION

There was almost four-fold rise in risk of head and neck cancer among opium users compared to non-users.

Opium as a carcinogen: A systematic review and meta-analysis

BACKGROUND

Opium and its pyrolysates have been investigated as potential carcinogenic material through several studies in different body systems; however, the results were controversial and no consensus was achieved with this regard. Thus, we aimed to systematically review and meta-analyze all existed evidence regarding association between opium consumption and cancer.

METHODS

Four major electronic databases including ISI Web of Science, PubMed, Scopus, and Embase along with Magiran and SID were searched thoroughly for all published articles from inception up to September 25, 2020. All studies were appraised critically by Newcastle Ottawa Scale (NOS) checklist. Relevant demographic data and the intended results of the selected studies were extracted and their Odds ratios (OR) were pooled using Comprehensive Meta-analysis (CMA). The cumulative risk of opium for developing different cancers was calculated.

FINDINGS

34 studies comprised of 18,230 individuals were entered in our systematic review and finally 32 publications were enrolled in meta-analysis. Overall, using the random effects model, opium consumption was associated with increased rate of malignancies in both minimally[OR = 4.14 95%CI = (3.32-5.15)] and fully adjusted [OR = 4.35 95%CI = (3.36-5.62)] analyses. Moreover, using random effects fully adjusted model, the subgroup analysis revealed increased risk for larynx [OR = 9.58 95%CI = (6.31-14.53)], respiratory [OR = 9.02 95%CI = (6.27-12.96)], head and neck [OR = 8•03 95%CI = (4.03-16.00)], and colon [OR=5.58 95%CI = (3.14-9.92)] cancers for opium consumers compared to non-consumers.

INTERPRETATION

Opium consumption is highly associated with all reported types of cancers, especially in fully adjusted model; however, basic pathophysiology should be further investigated.

FUNDING

None.

Is opium use associated with an increased risk of lung cancer? A case-control study

Background

In recent years, lung cancer (LC) incidence has increased in Iran. The use of opium and its derivatives (O&D) has increased as well. This study aimed to investigate the association between the use of O&D and LC incidence.

Methods

In this case-control study conducted in Kerman, Iran; 140 patients with lung cancer and 280 healthy controls matched by age, sex, and place of residence were included. Data, including O&D use, cigarette smoking, alcohol use, and diet, were collected using a structured questionnaire. The relation between the use of O&D and LC was evaluated using conditional logistic regression adjusted for tobacco smoking, education, daily intake of fruit, vegetables, red meat, and hydrogenated fats.

Results

Opium ever-use was associated with an increased risk of LC (Adjusted Odds Ratio (AOR) =5.95, 95% CI: 1.87–18.92). Participants were divided into low and high use groups based on the median of opium use in the control group. A significant dose-response relation was observed between the amount of daily O&D use and LC; and the relation was stronger in high users (AOR _{low users} = 3.81% CI: 1.13–12.77 and OR _{high users} = 9.36, 95% CI: 2.05–42.72). Also, LC was higher among participants starting the use of O&D at younger ages (≤ 41 years old vs never users AOR = 8.64, 95% CI: 1.90–39.18) compared to those who started at an older age (> 41 years old vs never users, AOR = 4.71, 95% CI: 1.38–16.08). The association between opium, and lung cancer among non-smokers was OR: 6.50 (95% CI: 2.89 to 14.64).

Conclusion

The results of this study show that opium use is probably a dose related risk factor for lung cancer.

Overexpression of Adiponectin Receptors in Opium Users with and without Cancer

Aim

Opium addiction is a serious public health concern in the Middle East countries causing various illnesses. Opium use is associated with an increased risk of several cancers; however, the underlying mechanisms are not yet fully elucidated. Altered levels of adiponectin and its related main receptors, Adiponectin receptor 1 and 2 (AdipoR1 and AdipoR2) have been associated with several malignancies. Opium users are at risk of various cancers. All together let us to the hypothesis that probable overexpression of AdipoRs in opium users might be linked to the occurrence of cancer in this population.

Methods

One hundred opium users along with 100 healthy non-opium users were enrolled in the study. Opium users were followed up for 5 years (2014–2019) to evaluate the occurrence of malignancies. AdipoR1 and AdipoR2 expressions were measured using a flow cytometry method.

Results

Expression of AdipoR1 and AdipoR2 was significantly higher in opium users compared with the healthy control group (P=0.0001 and 0.0001, respectively). Eight opium users developed cancer during the follow-up period. Subjects abusing opium developed cancer by 8.6 folds comparing to non-opium users (P=0.034; OR=8.6; 95% CI (1.06–70.1)). Expression of these two receptors was significantly higher in opium users developing cancer compared with cancer-free opium (P=0.001).

Conclusion

Considering the significant overexpression of AdipoR1 and AdipoR2 in opium users and in opium users who developed malignancies and the association between upregulation of these receptors in most cancers affecting opium users and assessment of AdipoRs may serve as an early detection tool of cancer in this population.

Opium use and subsequent incidence of cancer: results from the Golestan Cohort Study

BACKGROUND

Evidence is emerging for a role of opiates in various cancers. In this study, we aimed to investigate the association between regular opium use and cancer incidence.

METHODS

This study was done in a population-based cohort of 50 045 individuals aged 40-75 years from northeast Iran. Data on participant demographics, diet, lifestyle, opium use, and different exposures were collected upon enrolment using validated questionnaires. We used proportional hazards regression models to estimate hazard ratios (HRs) and corresponding 95% CIs for the association between opium use and different cancer types.

FINDINGS

During a median 10 years of follow-up, 1833 participants were diagnosed with cancer. Use of opium was associated with an increased risk of developing all cancers combined (HR 1·40, 95% CI 1·24-1·58), gastrointestinal cancers (1·31, 1·11-1·55), and respiratory cancers (2·28, 1·58-3·30) in a dose-dependent manner (ptrend<0·001). For site-specific cancers, use of opium was associated with an increased risk of developing oesophageal (1·38, 1·06-1·80), gastric (1·36, 1·03-1·79), lung (2·21, 1·44-3·39), bladder (2·86, 1·47-5·55), and laryngeal (2·53, 1·21-5·29) cancers in a dose-dependent manner (ptrend<0·05). Only high-dose opium use was associated with pancreatic cancer (2·66, 1·23-5·74). Ingestion of opium (but not smoking opium) was associated with brain (2·15, 1·00-4·63) and liver (2·46, 1·23-4·95) cancers in a dose-dependent manner (prend<0·01). We observed consistent associations among ever and never tobacco users, men and women, and individuals with lower and higher socioeconomic status.

INTERPRETATION

Opium users have a significantly higher risk of developing cancers in different organs of the respiratory, digestive, and urinary systems and the CNS. The results of this analysis show that regular use of opiates might increase the risk of a range of cancer types.

FUNDING

World Cancer Research Fund International, Cancer Research UK, Tehran University of Medical Sciences, US National Cancer Institute, International Agency for Research on Cancer.

Impact of cooking oil fume exposure and fume extractor use on lung cancer risk in non-smoking Han Chinese women

Smoking tobacco is the major risk factor for developing lung cancer. However, most Han Chinese women with lung cancer are nonsmokers. Chinese cooking methods usually generate various carcinogens in fumes that may inevitably be inhaled by those who cook the food, most of whom are female. We investigated the associations of cooking habits and exposure to cooking fumes with lung cancer among non-smoking Han Chinese women. This study was conducted on 1,302 lung cancer cases and 1,302 matched healthy controls in Taiwan during 2002–2010. Two indices, “cooking time-years” and “fume extractor use ratio,” were developed. The former was used to explore the relationship between cumulative exposure to cooking oil fumes and lung cancer; the latter was used to assess the impact of fume extractor use for different ratio-of-use groups. Using logistic models, we found a dose–response association between cooking fume exposure and lung cancer (odds ratios of 1, 1.63, 1.67, 2.14, and 3.17 across increasing levels of cooking time-years). However, long-term use of a fume extractor in cooking can reduce the risk of lung cancer by about 50%. Furthermore, we provide evidence that cooking habits, involving cooking methods and oil use, are associated with risk of lung cancer.

Space-Time Statistical Insights about Geographic Variation in Lung Cancer Incidence Rates: Florida, USA, 2000⁻2011

The geographic distribution of lung cancer rates tends to vary across a geographic landscape, and covariates (e.g., smoking rates, demographic factors, socio-economic indicators) commonly are employed in spatial analysis to explain the spatial heterogeneity of these cancer rates. However, such cancer risk factors often are not available, and conventional statistical models are unable to fully capture hidden spatial effects in cancer rates. Introducing random effects in the model specifications can furnish an efficient approach to account for variations that are unexplained due to omitted variables. Especially, a random effects model can be effective for a phenomenon that is static over time. The goal of this paper is to investigate geographic variation in Florida lung cancer incidence data for the time period 2000–2011 using random effects models. In doing so, a Moran eigenvector spatial filtering technique is utilized, which can allow a decomposition of random effects into spatially structured (SSRE) and spatially unstructured (SURE) components. Analysis results confirm that random effects models capture a substantial amount of variation in the cancer data. Furthermore, the results suggest that spatial pattern in the cancer data displays a mixture of positive and negative spatial autocorrelation, although the global map pattern of the random effects term may appear random.

Mortality from respiratory diseases associated with opium use: a population-based cohort study

BACKGROUND

Recent studies have suggested that opium use may increase mortality from cancer and cardiovascular diseases. However, no comprehensive study of opium use and mortality from respiratory diseases has been published. We aimed to study the association between opium use and mortality from respiratory disease using prospectively collected data.

METHODS

We used data from the Golestan Cohort Study, a prospective cohort study in northeastern Iran, with detailed, validated data on opium use and several other exposures. A total of 50 045 adults were enrolled from 2004 to 2008, and followed annually until June 2015, with a follow-up success rate of 99%. We used Cox proportional hazard regression models to evaluate the association between opium use and outcomes of interest.

RESULTS

During the follow-up period, 331 deaths from respiratory disease were reported (85 due to respiratory malignancies and 246 due to non-malignant aetiologies). Opium use was associated with an increased risk of death from any respiratory disease (adjusted HR 95% CI 3.13 (2.42 to 4.04)). The association was dose-dependent with a HR of 3.84 (2.61 to 5.67) for the highest quintile of cumulative opium use versus never use (Ptrend<0.001). The HRs (95% CI) for the associations between opium use and malignant and non-malignant causes of respiratory mortality were 1.96 (1.18 to 3.25) and 3.71 (2.76 to 4.96), respectively.

CONCLUSIONS

Long-term opium use is associated with increased mortality from both malignant and non-malignant respiratory diseases.

Opium use, cigarette smoking, and alcohol consumption in relation to pancreatic cancer

BACKGROUND AND AIMS

Although several studies have suggested opium as a risk factor for cancers of the esophagus, stomach, larynx, lung, and bladder, no previous study has examined the association of opium with pancreatic cancer. We aimed to study the association between opium use and risk of pancreatic cancer in Iran, using a case-control design. We also studied the association of cigarette smoking and alcohol consumption with pancreatic cancer, for which little information was available from this population.

METHODS

Cases and controls were selected from patients who were referred to 4 endoscopic ultrasound centers in Tehran, Iran. We recruited 316 histopathologically (all adenocarcinoma) and 41 clinically diagnosed incident cases of pancreatic cancer, as well as 328 controls from those with a normal pancreas in enodosonography from January 2011 to January 2015. We used logistic regression models to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

After adjustment for potential confounders, opium use (OR 1.91; 95% CI 1.06-3.43) and alcohol consumption (OR 4.16; 95% CI 1.86-9.31) were significantly associated with an increased risk of pancreatic cancer. We did not find an association between ever tobacco smoking and pancreatic cancer risk (OR 0.93; 95% CI 0.62-1.39).

CONCLUSION

In our study, opium use and alcohol consumption were associated with an increased risk of pancreatic cancer, whereas cigarette smoking was not.

Domestic incense use and lung cancer in Asia: a review

While there is strong evidence for the association between household air pollution and lung cancer among non-smoking women, the association between domestic incense use and lung cancer risk has been inconsistent. We conducted a systematic review of PubMed articles authored between 1969 and August 25, 2015 before performing a manual review of each study, and found a total of seven published studies on this topic. Most of the studies are case-control in design and did not further stratify by sex and smoking status. Of the seven studies, three reported positive associations, three reported null associations and one study found a negative association between incense use and lung cancer. Only one study reported estimates for non-smoking women. Future studies should be larger in sample size, stratify by both sex and smoking status in their analyses, and collect more detailed information on incense use in order to facilitate the understanding of the association between domestic incense use and lung cancer risk among non-smoking women in Asia.

Incidence trends of lung cancer by immigration status among Chinese Americans

BACKGROUND

Lung cancer is the leading cause of cancer-related death among Chinese Americans. A detailed examination of incidence trends by immigration status and histology may inform the etiology of lung cancer in this growing population.

METHODS

California Cancer Registry data were enhanced with data on patient nativity. Lung cancer incidence rates for Chinese males and females were computed for the years 1990-2010, and rates by immigration status and histology were computed for 1990-2004. Trends were assessed with annual percentage change (APC) statistics (two-sided P values) based on linear regression.

RESULTS

A total of 8,167 lung cancers were diagnosed among California Chinese from 1990 to 2010. Overall incidence increased nonstatistically among U.S.-born males (APC, 2.1; 95% CI, -4.9 to 9.7), but decreased significantly among foreign-born (APC, -1.7; 95% CI, -2.9 to -0.6). Statistically significant decreasing trends were observed for non-small cell lung cancer (NSCLC), specifically the squamous cell and large cell carcinoma subtypes among foreign-born males. Among females, incidence decreased nonsignificantly among U.S.-born (APC, -2.8; 95% CI, -9.1 to 4.0) but was stable among foreign-born (APC, -0.4; 95% CI, -1.7 to 1.0). A statistically significant decreasing trend was observed for squamous cell among foreign-born females.

CONCLUSIONS

These data provide critical evidence base to inform screening, research, and public health priorities in this growing population.

IMPACT

Given the low smoking prevalence among Chinese Americans, especially females, and few known lung cancer risk factors in U.S. never-smoker populations, additional research of etiologic genetic or biologic factors may elucidate knowledge regarding lung cancer diagnosed in never smokers.

An individual risk prediction model for lung cancer based on a study in a Chinese population

AIMS AND BACKGROUND

Early detection and diagnosis remains an effective yet challenging approach to improve the clinical outcome of patients with cancer. Low-dose computed tomography screening has been suggested to improve the diagnosis of lung cancer in high-risk individuals. To make screening more efficient, it is necessary to identify individuals who are at high risk.

METHODS AND STUDY DESIGN

We conducted a case-control study to develop a predictive model for identification of such high-risk individuals. Clinical data from 705 lung cancer patients and 988 population-based controls were used for the development and evaluation of the model. Associations between environmental variants and lung cancer risk were analyzed with a logistic regression model. The predictive accuracy of the model was determined by calculating the area under the receiver operating characteristic curve and the optimal operating point.

RESULTS

Our results indicate that lung cancer risk factors included older age, male gender, lower education level, family history of cancer, history of chronic obstructive pulmonary disease, lower body mass index, smoking cigarettes, a diet with less seafood, vegetables, fruits, dairy products, soybean products and nuts, a diet rich in meat, and exposure to pesticides and cooking emissions. The area under the curve was 0.8851 and the optimal operating point was obtained. With a cutoff of 0.35, the false positive rate, true positive rate, and Youden index were 0.21, 0.87, and 0.66, respectively.

CONCLUSIONS

The risk prediction model for lung cancer developed in this study could discriminate high-risk from low-risk individuals.

Gender susceptibility for cigarette smoking-attributable lung cancer: a systematic review and meta-analysis

OBJECTIVES

As the primary cause of lung cancer, whether smoking confers the same risk of lung cancer for women as men is unclear. Therefore, we aimed to compare male and female susceptibility for cigarette smoking-attributable lung cancer.

METHODS

A systematic review and meta-analysis was conducted by searching articles published up to July 2013 in three online databases (MEDLINE, EMBASE, and Cochrane Database). All studies estimated the association of cigarette smoking with the risk of lung cancer between men and women, respectively. A random effects model with inverse variance weighting was used to pool data. Male to female ratio of relative risk (RRR) was calculated to compare male and female susceptibility for cigarette smoking-attributable lung cancer.

RESULTS

47 articles containing 404,874 individuals were included in the final analysis. Compared with non-smokers, male to female RRR was 1.61 (95%CI: 1.37, 1.89) among current smokers. Based on pathological type, adenocarcinoma had the highest RRR (1.42; 95%CI: 0.86, 2.35), followed by squamous cancer and small cell lung cancer. Furthermore, compared with non-smoking men, current smoking men had higher risk of lung cancer than women in spite of smoking quantity, smoking duration or years since quitting.

CONCLUSIONS

These findings indicated that males had higher susceptibility for cigarette smoking-attributable lung cancer than females. It is contradicted with traditional opinion that females would be more easily suffered from cigarette smoking-attributable health problems than males. Hence, tobacco control is very crucial in both males and females.

Opium use: an emerging risk factor for cancer?

An estimated 16·5 million people worldwide illicitly use opiates, of whom 4 million use raw opium. We did a systematic review to investigate the association between opium use and cancer incidence and mortality. Opium use was associated with an increased risk of cancers of the oesophagus, stomach, larynx, lung, and urinary bladder. Although the present evidence suggests that these associations are possibly causal, further epidemiological studies (particularly prospective studies that collect detailed data about lifetime opium use and control for a broad range of potential confounders) are needed.

Dose-response relationship of lung cancer to amount smoked, duration and age starting

AIM: To quantify smoking/lung cancer relationships accurately using parametric modelling.

METHODS: Using the International Epidemiological Studies on Smoking and Lung Cancer database of all epidemiological studies of 100+ lung cancer cases published before 2000, we analyzed 97 blocks of data for amount smoked, 35 for duration of smoking, and 27 for age started. Pseudo-numbers of cases and controls (or at risk) estimated from RRs by dose level formed the data modelled. We fitted various models relating log_e RR to dose (d), including βd, βd^Y and βlog_e (1 + Wd), and investigated goodness-of-fit and heterogeneity between studies.

RESULTS: The best-fitting models for log_e RR were 0.833 log_e [1 + (8.1c/10)] for cigarettes/d (c), 0.792 (y/10)^0.74 for years smoked (y) and 0.176 [(70 - a)/10]^1.44 for age of start (a). Each model fitted well overall, though some blocks misfitted. RRs rose from 3.86 to 22.31 between c = 10 and 50, from 2.21 to 13.54 between y = 10 and 50, and from 3.66 to 8.94 between a = 30 and 12.5. Heterogeneity (P < 0.001) existed by continent for amount, RRs for 50 cigarettes/d being 7.23 (Asia), 26.36 (North America) and 22.16 (Europe). Little heterogeneity was seen for duration of smoking or age started.

CONCLUSION: The models describe the dose-relationships well, though may be biased by factors including misclassification of smoking status and dose.

Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

BACKGROUND

Smoking is a known lung cancer cause, but no detailed quantitative systematic review exists. We summarize evidence for various indices.

METHODS

Papers published before 2000 describing epidemiological studies involving 100+ lung cancer cases were obtained from Medline and other sources. Studies were classified as principal, or subsidiary where cases overlapped with principal studies. Data were extracted on design, exposures, histological types and confounder adjustment. RRs/ORs and 95% CIs were extracted for ever, current and ex smoking of cigarettes, pipes and cigars and indices of cigarette type and dose-response. Meta-analyses and meta-regressions investigated how relationships varied by study and RR characteristics, mainly for outcomes exactly or closely equivalent to all lung cancer, squamous cell carcinoma ("squamous") and adenocarcinoma ("adeno").

RESULTS

287 studies (20 subsidiary) were identified. Although RR estimates were markedly heterogeneous, the meta-analyses demonstrated a relationship of smoking with lung cancer risk, clearly seen for ever smoking (random-effects RR 5.50, CI 5.07-5.96) current smoking (8.43, 7.63-9.31), ex smoking (4.30, 3.93-4.71) and pipe/cigar only smoking (2.92, 2.38-3.57). It was stronger for squamous (current smoking RR 16.91, 13.14-21.76) than adeno (4.21, 3.32-5.34), and evident in both sexes (RRs somewhat higher in males), all continents (RRs highest for North America and lowest for Asia, particularly China), and both study types (RRs higher for prospective studies). Relationships were somewhat stronger in later starting and larger studies. RR estimates were similar in cigarette only and mixed smokers, and similar in smokers of pipes/cigars only, pipes only and cigars only. Exceptionally no increase in adeno risk was seen for pipe/cigar only smokers (0.93, 0.62-1.40). RRs were unrelated to mentholation, and higher for non-filter and handrolled cigarettes. RRs increased with amount smoked, duration, earlier starting age, tar level and fraction smoked and decreased with time quit. Relationships were strongest for small and squamous cell, intermediate for large cell and weakest for adenocarcinoma. Covariate-adjustment little affected RR estimates.

CONCLUSIONS

The association of lung cancer with smoking is strong, evident for all lung cancer types, dose-related and insensitive to covariate-adjustment. This emphasises the causal nature of the relationship. Our results quantify the relationships more precisely than previously.

Characteristics of polycyclic aromatic hydrocarbon emissions of particles of various sizes from smoldering incense

Release of polycyclic aromatic hydrocarbons (PAHs) in particles of various sizes from smoldering incenses was determined. Among the three types of incense investigated, yielding the total PAH emission rate and factor ranges for PM0.25 were 2,139.7-6,595.6 ng/h and 1,762.2-8,094.9 ng/g, respectively. The PM0.25/PM2.5 ratio of total PAH emission factors and rates from smoldering three incenses was greater than 0.92. This study shows that total particle PAH emission rates and factors were mainly <0.25 μm. Furthermore, the total toxic equivalency emission rates and factors of PAHs for PM0.25 were 241.3-469.7 and 198.8-576.2 ng/g from the three smoldering incenses. The benzo[a]pyrene accounted for 65.2%-68.0% of the total toxic equivalency emission factor of PM2.5 for the three incenses. Experimental results clearly indicate that the PAH emission rates and factors were influenced significantly by incense composition, including carbon and hydrogen content. The study concludes that smoldering incense with low atomic hydrogen/carbon ratios minimized the production of total polycyclic aromatic hydrocarbons of both PM2.5 and PM0.25.

Characterization of polycyclic aromatic hydrocarbon emissions in the particulate phase from burning incenses with various atomic hydrogen/carbon ratios

Polycyclic aromatic hydrocarbons in the particulate phase generated from burning various incense was investigated by a gas chromatography/mass spectrometry. Among the used incenses, the atomic H/C ratio ranged from 0.51 to 1.69, yielding the emission factor ranges for total particulate mass and PAHs of 4.19-82.16 mg/g and 1.20-9.50 μg/g, respectively. The atomic H/C ratio of the incense was the key factor affecting particulate mass and the PAHs emission factors. Both the maximum emission factor and the slowest burning rate appear at the H/C ratio of 1.57. The concentrations of the four-ring PAHs predominated and the major species among the 16 PAHs were fluoranthene, phenanthrene, pyrene, and chrysene for most incense types. The benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, and dibenzo[a,h]anthracene accounted for 87.08-93.47% of the total toxic equivalency emission factor.

A case-referent study of lung cancer and incense smoke, smoking, and residential radon in Chinese men

BACKGROUND

Burning incense generates large amounts of air pollutants, many of which are confirmed or suspected human lung carcinogens.

OBJECTIVES

We conducted a population-based case-referent study to examine the effect of incense smoke exposure on lung cancer risk among Chinese males and explored the joint effect of cigarette smoking and exposure to residential radon.

METHODS

We recruited 1,208 male lung cancer incident cases and 1,069 community referents from 2004 to 2006 and estimated their lifetime exposures to incense smoke and other residential indoor air pollutants based on self-reported information collected during interviews. We performed unconditional multivariable logistic regression analysis to estimate the odds ratio (OR) for lung cancer associated with exposure to incense smoke after adjusting for possible confounders. We conducted stratified analyses by smoking status and exposures to incense burning and residential radon and explored the potential additive-scale interactions.

RESULTS

We observed an association between incense exposure and lung cancer that was limited primarily to smokers. Cigarette smoking and high cumulative incense exposure at home appeared to have a synergistic effect on lung cancer (compared with never-smokers who never used incense, the OR for lung cancer for smokers who used incense ≥ 60 day-years = 5.00; 95% confidence interval: 3.34, 7.51). Power was limited, but we also found preliminary evidence suggesting that radon exposure may increase risk among smokers using incense.

CONCLUSION

Our study suggests that exposure to incense smoke in the home may increase the risk of lung cancer among smokers and that exposure to radon may further increase risk.

Risk factors for lung cancer: a case-control study in Hong Kong women

To identify etiological connections of lung cancer in Chinese women in Hong Kong, who are among the highest in lung cancer incidence and mortality, we conducted a case-control study, in which 279 female lung cancer cases and 322 controls were selected and frequency matched. A variety of information, including dietary habits, occupational history, smoking, domestic environmental exposures, and family history of cancer was collected, and their associations with lung cancer were analyzed with logistic analysis approach. In addition to positive associations with exposures to cooking emissions and to radon at home, smoking and family cancer history, we observed that increasing consumption of meat was linked to a higher risk, whereas consumptions of vegetables had a strong protective effect against lung cancer. Moderate consumption of coffee appeared to be beneficial against the disease. Those never employed and domestic helpers were at a higher risk. The results indicated that environmental exposures, risky personal behaviors, or lifestyle, as well as family cancer aggregation are among important contributors to the high incidence of lung cancer in Hong Kong females.

Challenge assay: A functional biomarker for exposure-induced DNA repair deficiency and for risk of cancer

A variety of biomarkers have been used to monitor exposed populations to determine potential health hazards from their exposure to environmental toxic agents. However, the majority of these biomarkers have been focused onto the identification of biological damage from the exposure. Therefore, there is a need to develop functional biomarkers that can identify exposure-induced functional deficiencies. More importantly, these deficiencies should be positioned along pathways that are responsible for the development of specific diseases. One of such pathways belongs to the extensive and complex DNA-repair machinery. The machinery thus becomes a large target for damage from environmental toxic agents. The hypothesis is that damage to any component of a repair pathway will interfere with the pathway-specific repair activities. Therefore, when cells from exposed populations are challenged with a DNA-damaging agent in vitro, the in vivo exposure-induced repair deficiency will be dramatically amplified and the deficiency will be detectable in a challenge assay as increased chromosome aberrations, micronuclei or un-repaired DNA strand breaks. The challenge assay has been used in different laboratories to show that a variety of exposed populations (with exposure to air pollutants, arsenic, benzene, butadiene, cigarette smoke, incense smoke, lead, mercury, pesticides, uranium or xylene but not to low concentrations of air pollutants or butadiene) expressed abnormal challenge response. The predicted health consequences of some of these studies have also been validated. Therefore, the challenge assay is a useful functional biomarker for population studies. Details of the challenge assay and its application will be presented in this review.

Effect of rice and salty rice diets on the structure of mouse stomach

The effect of rice and salty rice diets on stomach morphology was investigated in Swiss/ICR mice. Mice were fed rice, salty rice, or standard pellet diets for 3-12 months, starting when the mice were 4 weeks of age. Long-term maintenance on the rice or salty rice diet increased the dimension and wet weight of the forestomach and decreased the same parameters of the glandular stomach. Similar bidirectional changes of the forestomach (hypertrophy) and glandular stomach (atrophy) were produced by hydrocortisone treatment. Histological study showed that a reduction in the parietal cell population accounted for the regression of the glandular stomach in both cases. Evidence is presented to suggest that an excess of carbohydrate and sodium chloride combined with a deficiency of fat and protein produced steroidal disorders that in turn gave rise to hyperplasia of the forestomach and atrophy of the glandular stomach of the mice. Possible impact of the above findings on the genesis of human gastric cancer is discussed in relation to the metabolic competence of the host animals to synthesize vitamin C.

Socioeconomic differences in lung cancer incidence: a systematic review and meta-analysis

OBJECTIVE

To investigate the associations between various socioeconomic indicators and lung cancer incidence.

METHODS

We searched PubMed and EMBASE databases for studies on socioeconomic position (SEP) and lung cancer incidence published through October 2007. Random-effect model was used to pool the risk estimates from the individual studies. We stratified the analysis by adjustment strategy to investigate the influence of smoking on socioeconomic gradient in lung cancer incidence.

RESULTS

Out of 3,288 citations, we identified 64 studies eligible for inclusion. Compared to the highest SEP level, we observed an overall increased risk in lung cancer incidence among people with low educational SEP (61%), low occupational SEP (48%), and low income-based SEP (37%). The negative social gradient for lung cancer incidence remained for most of the possible sets of pooled estimates obtained in subgroup analyses for occupational and educational SEP with less consistency for SEP based on income in studies adjusted and unadjusted for smoking. No evidence of publication bias was apparent.

CONCLUSION

Lung cancer incidence was associated with low educational, occupational, and income-based SEP. The association, adjusted or unadjusted for smoking, points out the importance of social position to be addressed in all discussions on cancer preventive measures.

The roles of smoking and cooking emissions in lung cancer risk among Chinese women in Hong Kong

BACKGROUND

We conducted this case-control study to evaluate smoking effect on lung cancer conditional on the level of exposure to cooking emissions and to explore whether there is a joint effect of these two risk factors.

SUBJECTS AND METHODS

We selected 279 newly diagnosed primary lung cancer cases and 322 community controls from Hong Kong females, frequency matched by age group, and collected relevant data. We applied logistic regression to estimate lung cancer risk related to smoking and cooking fume exposure, expressed as total cooking dish-years, while adjusting for various potential confounding factors.

RESULTS

Current smoking was associated with four-fold increased risk, and ex-smoking with two-fold risk, which was not much influenced by cooking dish-years. No increased risk was observed in environmental tobacco smoking. Increasing intakes of yellow/orange vegetables and multivitamins were significant protective factors in all models. In the analysis of joint effect, the combination of smoking and cooking dish-years tended to have a greater risk than exposure to cooking fumes alone. There was a dose-response gradient with total dish-years in nonsmokers, but not in smokers. Smoking was more strongly associated with nonadenocarcinoma, whereas exposure to cooking fumes appeared to be related to both adenocarcinoma and nonadenocarcinoma.

CONCLUSION

We confirmed the important roles of smoking and cooking emissions in lung cancer risk among the women. These two major risk factors appeared to act independently.

Effects of exogenous antioxidants on dietary iron overload

In dietary iron overload, excess hepatic iron promotes liver damage. The aim was to attenuate free radical-induced liver damage using vitamins. Four groups of 60 Wistar rats were studied: group 1 (control) was fed normal diet, group 2 (Fe) 2.5% pentacarbonyl iron (CI) followed by 0.5% Ferrocene, group 3 (Fe + V gp) CI, Ferrocene, plus vitamins A and E (42× and 10× RDA, respectively), group 4 (Fe – V gp) CI, Ferrocene diet, minus vitamins A and E. At 20 months, glutathione peroxidase (GPx), superoxide dismutase (SOD), Oxygen Radical Absorbance Capacity (ORAC), Ames mutagenicity test, AST, ALT and 4-hydroxynonenal (4-HNE) immunohistochemistry were measured. 8OHdG levels of the Fe + V and Fe – V groups were 346 ± 117 and 455 ± 151, ng/g w.wt, respectively. Fe + V and Fe – V differences were significant (p<0.005). A positive correlation between DNA damage and mutagenesis existed (p<0.005) within the iron-fed gps. AST levels for Fe + V and Fe – V groups were 134.6 ± 48.6 IU and 202.2 ± 50.5 IU, respectively. Similarly, ALT levels were 234.6 ± 48.3 IU and 329.0 ± 48.6 IU, respectively. However, Fe – V and Fe + V groups transaminases were statistically insignificant. 4-HNE was detected in Fe + V and Fe – V gp livers. Vitamins A and E could not prevent hepatic damage.

Incense use and respiratory tract carcinomas: a prospective cohort study

BACKGROUND

Incense use is an integral part of daily life in large parts of Asia. The burning of incense is a powerful producer of particulate matter and the smoke contains a multitude of well-characterized carcinogens. However, to the authors' knowledge, no convincing association has been reported between exposure to incense smoke and the development of cancer. Therefore, the relation between incense use and the risk of respiratory tract carcinomas was analyzed in a prospective cohort study.

METHODS

Between 1993 and 1998, a population-based cohort of 61,320 Singapore Chinese who were free of cancer and ages 45 to 74 years completed a comprehensive interview regarding living conditions and dietary and lifestyle factors. Through linkage to population-based registries, the cohort was followed through 2005 and cancer occurrence determined. The relative risk for these cancers associated with incense use was estimated using a Cox proportional hazards model.

RESULTS

A total of 325 upper respiratory tract (UPT) carcinomas and 821 lung carcinomas were observed during follow-up. Incense use was associated with a significantly increased risk of UPT carcinomas other than nasopharyngeal, whereas no overall effect was observed on lung cancer. The duration and intensity of incense use were associated with an increased risk of squamous cell carcinomas in the entire respiratory tract (P for trend = .004), whereas there was no significant association noted between incense use and nonsquamous cell carcinomas. The relative risk of squamous cell carcinomas among long-term incense users was 1.8 (95% confidence interval [95% CI], 1.2-2.6; P = .004) in the entire respiratory tract.

CONCLUSIONS

The results of the current study indicate that long-term use of incense is associated with an increased risk of squamous cell carcinoma of the respiratory tract.

Determination of particulate-bound formaldehyde from burning incense by solid phase microextraction

This work studied the feasibility of using a solid phase microextraction (SPME) fiber for sampling and analysis of gaseous formaldehyde as well as particulate-bound formaldehyde from burning Chinese incense. The SPME fiber with PDMS/DVB coating were partially coated with o-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA), and used for sampling formaldehyde. The sampling rate for formaldehyde and its dependence on temperature, relative humidity and sampling time were observed. The same PFBHA treated fibers were, in parallel, exposed to incense burning smoke with pre-filtration and without pre- filtration for 0.5-1 min. The NIOSH method 2541 using an XAD-2 tube at a flow rate of 0.1 Lpm was also applied for sampling simultaneously. The results demonstrate that commercially available PDMS/DVB fibers partially coated with PFBHA are capable of sampling the gas phase of formaldehyde as well as particulate-bound formaldehyde. The determined level of formaldehyde was close to the result obtained by the NIOSH method 2541. However, a reduction of the fiber's formaldehyde loading capacity in the aerosol sampling in comparison with gas sampling was noticed. This indicates that the particulate characteristics, and their bound chemicals other than formaldehyde may influence the maximum loading capacity of formaldehyde, and some characteristic particulates in high concentrations may even deteriorate the fiber coating.

Hormone replacement therapy and lung cancer risk in Chinese

BACKGROUND

The association between hormone replacement therapy (HRT) and a reduced lung cancer risk has been reported in previous studies. There is a high female to male ratio in Chinese lung cancer patients, and female patients have different clinicopathological characteristics compared with Western patient populations. The authors investigated whether HRT may reduce lung cancer risk in Taiwan.

METHODS

The authors used a case-control study design to investigate 826 women with lung cancer and 531 healthy controls. Personal interviews based on a structured questionnaire were performed to collect information on HRT use of at least 3 months, age, ethnicity, active and passive smoking, exposure to air pollution, cooking or incense fumes, body mass index (BMI), menopause, and family history of cancers.

RESULTS

HRT use was associated with reduced lung cancer risk with a multivariate, adjusted odds ratio of 0.70 (95% CI, 0.53-0.94; P = .019). HRT use was associated with reduced odds ratio of lung cancer in all subset analyses stratified by histology, active and passive cigarette smoking, BMI, history of incense burning, cooking, and motorcycle riding, as well as family history of certain cancers.

CONCLUSIONS

This study confirmed that HRT is associated with a reduced lung cancer risk. The results appeared to be applicable to Chinese female population groups.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Dose-response relationship between cooking fumes exposures and lung cancer among Chinese nonsmoking women

The high incidence of lung cancer among Chinese females, despite a low smoking prevalence, remains poorly explained. Cooking fume exposure during frying could be an important risk factor. We carried out a population-based case-control study in Hong Kong. Cases were Chinese female nonsmokers with newly diagnosed primary lung cancer. Controls were female nonsmokers randomly sampled from the community, frequency matched by age groups. Face-to-face interviews were conducted using a standardized questionnaire. The "total cooking dish-years," categorized by increments of 50, was used as a surrogate of cooking fumes exposure. Multiple unconditional logistic regression was used to estimate the odds ratios (OR) for different levels of exposure after adjusting for various potential confounding factors. We interviewed 200 cases and 285 controls. The ORs of lung cancer across increasing levels of cooking dish-years were 1, 1.17, 1.92, 2.26, and 6.15. After adjusting for age and other potential confounding factors, the increasing trend of ORs with increasing exposure categories became clearer, being 1, 1.31, 4.12, 4.68, and 34. The OR of lung cancer was highest for deep-frying (2.56 per 10 dish-years) followed by that of frying (1.47), and stir-frying had the lowest OR (1.12) among the three methods. Cumulative exposure to cooking by means of any form of frying could increase the risk of lung cancer in Hong Kong nonsmoking women. Practical means to reduce exposures to cooking fumes should be given top priority in future research.

Smoking-adjusted lung cancer incidence among Asian-Americans (United States)

OBJECTIVE

Chinese women residing in Asia and Hawaii have low consumption of tobacco but a high incidence of lung cancer. To explore this question further, we conducted a study of lung cancer among Chinese women residing in mainland US.

METHODS

Using data from NCI's SEER program, we identified residents of Los Angeles County, the San Francisco Metropolitan Area, and the Seattle-Puget Sound Area who were 50 years or older, diagnosed with cancer of the lung or bronchus in 1999-2001, with race specified as non-Hispanic white (n = 18,493), Chinese (n = 853), Filipino (n = 615), or Japanese (n = 282). The sex-specific observed number of lung cancer cases among each Asian sub-group was compared to the expected number of lung cancer cases for each Asian sub-group. The expected number was determined by multiplying the age-, sex-, and geographic area-adjusted incidence rates for non-Hispanic whites by the age- and sex-specific ratio of percentage of current smokers in each Asian sub-group to whites in 1990, and then by the size of the respective Asian populations.

RESULTS

Chinese women had a four-fold increased risk of lung cancer, and Filipino women a two-fold increased risk, compared to that expected based on rates in US non-Hispanic whites with a similar proportion of cigarette smokers. Lung cancer among Chinese, Filipino, and Japanese males, as well as Japanese females, did not deviate from expected risk. Among Chinese women, the increased risk was largely restricted to adenocarcinoma and large cell undifferentiated carcinoma.

CONCLUSIONS

Chinese female residents of the western US mainland have a much higher risk of lung cancer than would be predicted from their tobacco use patterns, just as they do in Asia.

Gefitinib is more effective in never-smokers with non-small-cell lung cancer: experience among Asian patients

We retrospectively analysed the results of patients with advanced non-small-cell lung cancer treated with gefitinib to derive clinical factors predictive of response and a favourable survival outcome. Patients were treated with gefitinib 250 mg per day and re-evaluated 4–8 weeks later with repeat CT scan and every 8 weeks thereafter to assess response and the duration of response. Pathology review by a histopathologist was conducted, in particular to confirm a recently published result of bronchioloalveolar carcinoma histology or its components as predictive of response to gefitinib. Logistic regression and Cox regression analytical methods were applied to determine factors that could predict for response and improved overall survival. A total of 110 patients were treated. The overall response rate was 32% partial responses (PRs). Only never-smoking status was predictive of response in the logistic regression analysis, adjusted OR=6.1, 95% CI=1.7, 21.5. The presence of a PR and good performance status were predictive of a favourable survival outcome from the Cox regression modelling. Responders had an adjusted HR of 3.0, 95% CI=1.5–5.8 compared to nonresponders, while patients with ECOG status 0–1 had an adjusted HR of 0.42, 95% CI=0.25–0.72, compared with patients with ECOG status 2–4. Bronchioloalveolar carcinoma or its components were distinctly absent on pathology review. In conclusions, Never-smoking status is an important clinical predictor of a favourable response to gefitinib.

Patterns of lung cancer mortality in 23 countries: application of the age-period-cohort model

Background

Smoking habits do not seem to be the main explanation of the epidemiological characteristics of female lung cancer mortality in Asian countries. However, Asian countries are often excluded from studies of geographical differences in trends for lung cancer mortality. We thus examined lung cancer trends from 1971 to 1995 among men and women for 23 countries, including four in Asia.

Methods

International and national data were used to analyze lung cancer mortality from 1971 to 1995 in both sexes. Age-standardized mortality rates (ASMR) were analyzed in five consecutive five-year periods and for each five-year age group in the age range 30 to 79. The age-period-cohort (APC) model was used to estimate the period effect (adjusted for age and cohort effects) for mortality from lung cancer.

Results

The sex ratio of the ASMR for lung cancer was lower in Asian countries, while the sex ratio of smoking prevalence was higher in Asian countries. The mean values of the sex ratio of the ASMR from lung cancer in Taiwan, Hong Kong, Singapore, and Japan for the five 5-year period were 2.10, 2.39, 3.07, and 3.55, respectively. These values not only remained quite constant over each five-year period, but were also lower than seen in the western countries. The period effect, for lung cancer mortality as derived for the 23 countries from the APC model, could be classified into seven patterns.

Conclusion

Period effects for both men and women in 23 countries, as derived using the APC model, could be classified into seven patterns. Four Asian countries have a relatively low sex ratio in lung cancer mortality and a relatively high sex ratio in smoking prevalence. Factors other than smoking might be important, especially for women in Asian countries.

The Impact of Smoking Status on the Behavior and Survival Outcome of Patients With Advanced Non-small Cell Lung Cancer

STUDY OBJECTIVES

There are fundamental differences in characteristics between smokers and nonsmokers with non-small cell lung cancer (NSCLC). We aim to study the impact of smoking status on the behavior of the disease, and to identify differences in outcome between the two groups.

DESIGN

A retrospective analysis was done of patients with NSCLC seen during the period from January 1999 to August 2002. Clinical characteristics, survival outcome, and response to treatment were reviewed and compared between the smokers and nonsmokers.

SETTING

Department of Medical Oncology, National Cancer Center.

RESULTS

Of 317 patients analyzed, 117 patients (36.3%) were nonsmokers. Among the nonsmokers, 74.5% had adenocarcinoma and 73.9% were women. The smokers had poorer performance status, reported more weight loss, and had a higher mean age at diagnosis of almost 8 years than nonsmokers. One hundred eighty-seven patients (59%) had died as of December 31, 2002. The nonsmokers had a longer median survival, although this was not statistically significant. There were no statistically significant differences in survival and response to chemotherapy between the two groups after adjusting for known prognostic factors.

CONCLUSIONS

Despite the known differences in mutational spectra and clinical characteristics between smokers and nonsmokers with NSCLC, no differences in terms of response to chemotherapy and survival outcome were observed. This could imply that this disease is equally aggressive in these two groups. More research is needed to further delineate and characterize the differences between these two etiologically different forms of NSCLC.

Fruits, vegetables and lung cancer: a pooled analysis of cohort studies

Inverse associations between fruit and vegetable consumption and lung cancer risk have been consistently reported. However, identifying the specific fruits and vegetables associated with lung cancer is difficult because the food groups and foods evaluated have varied across studies. We analyzed fruit and vegetable groups using standardized exposure and covariate definitions in 8 prospective studies. We combined study-specific relative risks (RRs) using a random effects model. In the pooled database, 3,206 incident lung cancer cases occurred among 430,281 women and men followed for up to 6-16 years across studies. Controlling for smoking habits and other lung cancer risk factors, a 16-23% reduction in lung cancer risk was observed for quintiles 2 through 5 vs. the lowest quintile of consumption for total fruits (RR = 0.77; 95% CI = 0.67-0.87 for quintile 5; p-value, test for trend < 0.001) and for total fruits and vegetables (RR = 0.79; 95% CI = 0.69-0.90; p-value, test for trend = 0.001). For the same comparison, the association was weaker for total vegetable consumption (RR = 0.88; 95% CI = 0.78-1.00; p-value, test for trend = 0.12). Associations were similar between never, past, and current smokers. These results suggest that elevated fruit and vegetable consumption is associated with a modest reduction in lung cancer risk, which is mostly attributable to fruit, not vegetable, intake. However, we cannot rule out the possibility that our results are due to residual confounding by smoking. The primary focus for reducing lung cancer incidence should continue to be smoking prevention and cessation.

The Feeding of .BETA.-Carotene Down-Regulates Serum IgE Levels and Inhibits the Type I Allergic Response in Mice

Feed containing beta-carotene was administered orally to BALB/c mice immunized intraperitoneally with ovalbumin (OVA) for approximately 1 month. The titers of OVA-specific IgE, OVA-specific IgG1 and OVA-specific IgG2a in the mouse sera were determined. The OVA-specific IgE titer and OVA-specific IgG1 titer by mice fed beta-carotene were significantly inhibited. On the other hand, the OVA-specific IgG2a titer in mice fed beta-carotene was significantly greater than those of control mice. The OVA-specific IgE suppression of beta-carotene feeding was dose-dependent. We also examined the effect of fed beta-carotene on active systemic anaphylaxis. Feeding beta-carotene to mice immunized with OVA inhibited the immediate reduction of the body temperature induced by antigen stimulation. Furthermore, the increase in serum histamine in the mice fed beta-carotene under active systemic anaphylaxis was lower than in controls. We then examined the pattern of cytokine production by spleen cells from mice followed by restimulation with OVA in vitro. The spleen cells from the mice fed beta-carotene produced more IFN-gamma, IL-12 and IL-2 than those from the control group. In contrast, the spleen cells from the mice fed beta-carotene produced less IL-4, IL-5, IL-6, IL-10 than those from the control group. Furthermore, analysis of IFN-gamma mRNA levels of the splenocytes using the real-time quantitative RT-PCR technique revealed higher levels in the splenocytes from the mice fed beta-carotene. These findings suggest that feeding beta-carotene improves the helper T cell (T(H))1-T(H)2 balance, inhibiting specific IgE and IgG1 production and antigen-induced anaphylactic response.

Significantly lower rate of smoking in female compared to male patients with lung adenocarcinoma

To examine the relationship between smoking and lung adenocarcinoma in female patients, we performed a retrospective chart review for 470 patients with lung adenocarcinoma at our hospital. The proportions of non-smokers were higher in female patients than those of male patients. A significant difference in smoking history was found between female and male patients. Not only active smoking but also passive smoking may influence the development of female lung adenocarcinoma, which reinforces the need for effective programmes aimed refraining from smoking and cessation among men as well as women.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

BACKGROUND

Diets rich in fruit and vegetables have been recommended for preventing cancer. The evidence supporting this recommendation is based on observational studies, although results of several prospective studies have cast some doubts on whether fruit and vegetables are associated with cancer risk reduction.

OBJECTIVE

We sought to summarize evidence from case-control and prospective studies on fruit and vegetable intake and cancer risk with a meta-analytic approach.

DESIGN

Published case-control and cohort studies that reported on total vegetable and fruit intake and risk of cancer of several sites were included. Relative risks were estimated by using linear logistic regression models.

RESULTS

Case-control studies overall support a significant reduction in the risks of cancers of the esophagus, lung, stomach, and colorectum associated with both fruit and vegetables; breast cancer is associated with vegetables but not with fruit; and bladder cancer is associated with fruit but not with vegetables. The overall relative risk estimates from cohort studies suggest a protective effect of both fruit and vegetables for most cancer sites considered, but the risk reduction is significant only for cancers of the lung and bladder and only for fruit.

CONCLUSIONS

Prospective studies provide weaker evidence than do case-control studies of the association of fruit and vegetable consumption with reduced cancer risk. The discrepancies may be related to recall and selection biases in case-control studies. In contrast, the association may have been underestimated in prospective studies because of the combined effects of imprecise dietary measurements and limited variability of dietary intakes within each cohort.

Dietary factors and the risk of lung cancer in New Caledonia (South Pacific)

Our objective was to study the relations between the risk of lung cancer and dietary factors in New Caledonia, in the South Pacific. A population-based case-control study of respiratory cancers was conducted between 1993 and 1995 in New Caledonia; we analyzed data for 134 incident lung cancer cases (109 men and 25 women) and 295 controls (227 men and 68 women) who had completed a food frequency questionnaire. Odds ratios (ORs) associated with food and nutrient intakes were calculated with unconditional logistic regression, with adjustment for smoking, age, and ethnicity. Analyses were performed separately for men and women. Among men, no significant associations were observed with any foods, including vegetables and fruits. Nonetheless, high consumption of dark green leafy vegetables (highest vs. lowest tertile of intake) was associated with decreased risk (OR = 0.5, 95% confidence interval = 0.2-1.2, P for trend = 0.12), particularly among Melanesians (OR = 0.4, 95% confidence interval = 0.1-1.0, P for trend = 0.07). A similar protective effect was also suggested for high consumption of poultry (P for trend = 0.06) and fresh fish (P for trend = 0.08). No significant association was found with nutrients. Among women, the analyses concerned few subjects and were not informative. This study suggests that high consumption of dark green leafy vegetables may reduce the risk of lung cancer among men in this population.