Filter cigarette smoking and lung cancer risk; a hospital-based case--control study in Japan

Cumulative cigarette tar exposure and lung cancer risk among Japanese smokers

OBJECTIVE

Tar concentration in cigarette brands is chronologically decreasing in the USA and Japan. However, studies investigating lung cancer risk with cumulative tar exposure in Western and Asian countries are insufficient. To investigate the risk of lung cancer with cumulative cigarette tar exposure, we conducted a case-control study among Japanese current smokers.

METHODS

This study used data from the US-Japan lung cancer joint study in 1993-1998. A total of 282 subjects with histologically confirmed lung cancer and 162 hospital and 227 community controls were included in the study, and two control groups were combined. The information regarding tar concentration was obtained from the published documents and additional estimation using the equation of regression. Cumulative tar concentration was calculated by multiplying the annual value of brand-specific tar concentration by years of smoking. The odds ratios and 95% confidence intervals for lung cancer with cumulative tar exposure were estimated using a logistic model.

RESULTS

The odds ratios for lung cancer with both lower (1-59.8 × 105 mg) and higher (>59.8 × 105 mg) total cumulative tar exposure were statistically significant (3.81, 2.23-6.50 and 11.64, 6.56-20.67, respectively) with increasing trend (P < 0.001). The stratification analysis showed higher odds ratios in subjects with higher cumulative tar exposure regardless of inhalation, duration of smoking filtered cigarettes and histological type.

CONCLUSIONS

This study showed that cumulative tar exposure is a dose-dependent indicator for lung cancer risk, and low-tar exposure was still associated with increased cancer risk.

Recent Trends in Demographics, Surgery, and Prognosis of Patients with Surgically Resected Lung Cancer in a Single Institution from Korea

BACKGROUND

Over the past few decades, demographics information has changed significantly in patients with surgically resected lung cancer. Herein, we evaluated the recent trends in demographics, surgery, and prognosis of lung cancer surgery in Korea.

METHODS

Patients with surgically resected primary lung cancer from 2002 to 2016 were retrospectively analyzed. Multivariable Cox regression analysis was conducted to identify prognostic factors for overall survival. The annual percent change (APC) and statistical significance were calculated using the Joinpoint software.

RESULTS

A total of 7,495 patients were enrolled. Over the study period, the number of lung cancer surgeries continued to increase (P < 0.05). The proportion of women to total subjects has also increased (P < 0.05). The proportion of elderly patients (≥ 70 years) as well as those with tumors measuring 1-2 cm and 2-3 cm significantly increased in both genders (all P < 0.05). The proportion of patients with adenocarcinoma, video-assisted thoracic surgery, sublobar resection, and pathological stage I significantly increased (P < 0.05). The 5-year overall survival rate of lung cancer surgery increased from 61.1% in 2002-2006 to 72.1% in 2012-2016 (P < 0.001). The operative period was a significant prognostic factor in multivariable Cox analysis (P < 0.001).

CONCLUSION

The mean age of patients with lung cancer surgery increased gradually, whereas tumor size reduced. Prognosis of lung cancer surgery improved with recent increases in the frequency of adenocarcinoma, video-assisted thoracic surgery, sublobar resection, and pathological stage I. The operation period itself was also an independent prognostic factor for overall survival.

The relations among three popular indices of risks

The relative risk, risk difference, and odds ratio are three major indices of differences in risks of diseases between different groups. Although widely used in research and practice in biomedical and epidemiologic research, misconceptions are not uncommon about their relationships. Many publications offer contradicting advices in how to use them in studies. Some biomedical researchers believe that these indices are related in a monotone fashion, and, thus, changes in one direction in one of the indices can be interpreted as same directional changes in the other two. Misconceptions about these three indices such as the monotone relationship are so prevalent in the biomedical and epidemiologic research that clarifications of such popular beliefs are warranted. In this paper, we take a systematic approach to characterize the relationships among the indices. We develop key results to elucidate the intricate relationships between the indices. Our findings speak to the need for investigators to carefully consider the different indices before using them in their studies, since they are not interchangeable and results based on one index are generally not translatable into any of the others.

Predicting the survival of patients with lung adenocarcinoma using a four-gene prognosis risk model

Lung adenocarcinoma (LAD) is difficult to diagnose as it tends to be small in size and metastasize early. The aim of the present study was to investigate prognostic factors for patients with LAD and establish a prognosis risk model. A training set consisting of clinical and RNA sequencing data from 503 patients with LAD, as well as expression data from a further 59 LAD and adjacent tissues, was obtained from The Cancer Genome Atlas. Additionally, a validation dataset was acquired from the Gene Expression Omnibus database (GSE26939), which included clinical and gene expression data from 115 patients. Using the DESeq2 package to compare expression between LAD and adjacent tissues, differentially expressed genes (DEGs) were identified. On the basis of survival and the random forests for survival, regression and classification package, genes for constructing the prognosis risk model were selected. The prognosis risk model was constructed and validated using the survival package. Subsequently, high- and low-risk groups were compared using the Limma package to identify DEGs, and enrichment analysis was performed using the web-based gene set analysis toolkit. A protein-protein interaction network was visualized using Cytoscape software. There were 18,567 DEGs between the LAD samples and the adjacent tissues, and 363 DEGs between the high- and low-risk groups. Of these, four genes were selected for constructing the prognosis risk model, myosin IE (MYO1E), endoplasmic reticulum oxidoreductase 1α (ERO1L), C1q and tumor necrosis factor-related protein 6 (C1QTNF6) and family with sequence similarity 83, member A (FAM83A). The survival time of high- and low-risk groups in the validation set were significantly different. Functional enrichment revealed that the genes that interacted with MYO1E, ERO1L, C1QTNF6 and FAM83A separately were enriched in 'cell cycle regulation', 'synthesis and assembly of nucleic acids', 'histone modification and cell cycle progression' and 'cell secretion process'. The four-gene prognosis risk model could potentially be used for predicting the survival of patients with LAD.

Identification of the targets of hematoporphyrin derivative in lung adenocarcinoma using integrated network analysis

BACKGROUND

Hematoporphyrin derivative (HPD) has a sensibilization effect in lung adenocarcinoma. This study was conducted to identify the target genes of HPD in lung adenocarcinoma.

METHODS

RNA sequencing was performed using the lung adenocarcinoma cell line A549 after no treatment or treatment with X-ray or X-ray + HPD. The differentially expressed genes (DEGs) were screened using Mfuzz package by noise-robust soft clustering analysis. Enrichment analysis was carried out using "BioCloud" online tool. Protein-protein interaction (PPI) network and module analyses were performed using Cytoscape software. Using WebGestalt tool and integrated transcription factor platform (ITFP), microRNA target and transcription factor (TF) target pairs were separately predicted. An integrated regulatory network was visualized with Cytoscape software.

RESULTS

A total of 815 DEGs in the gene set G1 (continuously dysregulated genes along with changes in processing conditions [untreated-treated with X-ray-X-ray + treated with HPD]) and 464 DEGs in the gene set G2 (significantly dysregulated between X-ray + HPD-treated group and untreated/X-ray-treated group) were screened. The significant module identified from the PPI network for gene set G1 showed that ribosomal protein L3 (RPL3) gene could interact with heat shock protein 90 kDa alpha, class A member 1 (HSP90AA1). TFs AAA domain containing 2 (ATAD2) and protein inhibitor of activated STAT 1 (PIAS1) were separately predicted for the genes in gene set G1 and G2, respectively. In the integrated network for gene set G2, ubiquitin-specific peptidase 25 (USP25) was targeted by miR-200b, miR-200c, and miR-429.

CONCLUSION

RPL3, HSP90AA1, ATAD2, and PIAS1 as well as USP25, which is targeted by miR-200b, miR-200c, and miR-429, may be the potential targets of HPD in lung adenocarcinoma.

Tar level of cigarettes smoked and risk of smoking-related diseases

BACKGROUND

Opinions differ on the relationship between tar level and risk of smoking-related disease. However, except for lung cancer, few reviews have evaluated the epidemiological evidence. Here the relationship of tar level to risk of the four main smoking-related diseases is considered.

METHODS

Papers comparing risk of lung cancer, COPD, heart disease or stroke in smokers of lower and higher tar yield cigarettes were identified from reviews and searches, relative risk estimates being extracted comparing the lowest and highest tar groups. Meta-analyses investigated heterogeneity by various study characteristics.

RESULTS

Twenty-six studies were identified, nine of prospective design and 17 case-control. Two studies grouped cigarettes by nicotine rather than tar. Seventeen studies gave results for lung cancer, 16 for heart disease, five for stroke and four for COPD. Preferring relative risks adjusted for daily amount smoked, where adjusted and unadjusted estimates were available, combined estimates for lowest versus highest tar (or nicotine) groups were 0.78 (95% confidence interval 0.70-0.88) for lung cancer, 0.86 (0.81-0.91) for heart disease, 0.77 (0.62-0.95) for stroke and 0.81 (0.65-1.02) for COPD. Lower risks were generally evident in subgroups by publication period, gender, study design, location and extent of confounder adjustment. Estimates were similar preferring data unadjusted for amount smoked or excluding nicotine-based estimates.

CONCLUSIONS

Despite evidence that smokers substantially compensate for reduced cigarette yields, the results clearly show lower risks in lower tar smokers. Limitations of the evidence are discussed, but seem unlikely to affect this conclusion.

The relationship of cigarette smoking in Japan to lung cancer, COPD, ischemic heart disease and stroke: A systematic review

Background:  To present up-to-date meta-analyses of evidence from Japan relating smoking to major smoking-related diseases.  Methods:  We restricted attention to lung cancer, chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD) and stroke, considering relative risks (RRs) for current and ex-smokers relative to never smokers.  Evidence by amount smoked and time quit was also considered.  For IHD and stroke only, studies had to provide age-adjusted RRs, with age-specific results considered.  For each disease we extended earlier published databases to include more recent studies.  Meta-analyses were conducted, with random-effects RRs and tests of heterogeneity presented.  Results:  Of 40 studies, 26 reported results for lung cancer and 7 to 9 for each other disease.  For current smoking, RRs (95%CIs) were lung cancer 3.59 (3.25-3.96), COPD 3.57 (2.72-4.70), IHD 2.21 (1.96-2.50) and stroke 1.40 (1.25-1.57).  Ex-smoking RRs were lower.  Data for lung cancer and IHD showed a clear tendency for RRs to rise with increasing amount smoked and decrease with increasing time quit.  Dose-response data were unavailable for COPD and unclear for stroke, where the association was weaker.  Conclusions:  Compared to studies in other Asian and Western countries, current smoking RRs were quite similar for IHD and stroke.  The comparison is not clear for COPD, where the Japanese data, mainly from cross-sectional studies, is limited.  For lung cancer, the RRs are similar to those in other Asian countries, but substantially lower than in Western countries.  Explanations for this are unclear, but less accurate reporting of smoking by Japanese may contribute to the difference.

Epidemiology of Lung Cancer in Korea: Recent Trends

Lung cancer causes the most cancer deaths in Korea. Although the smoking rate has begun to decrease, the prevalence of lung cancer is still increasing. We reviewed the national lung cancer registry data and the data published about lung cancer in Korea. In 2012, the crude incidence rate of lung cancer was 43.9 per 100,000. The age-standardized mortality rate of lung cancer was 19.8 per 100,000. The 5-year relative survival rate for lung cancer was 11.3% from 1993 to 1995 and increased to 21.9% in the period from 2008 to 2012. Lung cancer occurring in never-smokers was estimated to increase in Korea. Adenocarcinoma is steadily increasing in both women and men and has replaced squamous cell carcinoma as the most common type of lung cancer in Korea. In patients with adenocarcinoma, the frequency of EGFR mutations was 43% (range, 20%–56%), while that of the EMK4-ALK gene was less than 5%.

Relationships among three popular measures of differential risks: relative risk, risk difference, and odds ratio

The relative risk, risk difference, and odds ratio are the three most commonly used measures for comparing the risk of disease between different groups. Although widely popular in biomedical and psychosocial research, the relationship among the three measures has not been clarified in the literature. Many researchers incorrectly assume a monotonic relationship, such that higher (or lower) values in one measure are associated with higher (or lower) values in the other measures. In this paper we discuss three theorems and provide examples demonstrating that this is not the case; there is no logical relationship between any of these measures. Researchers must be very cautious when implying a relationship between the different measures or when combining results of studies that use different measures of risk.

Hazard Ratio of Smoking on Lung Cancer in Korea According to Histological Type and Gender

PURPOSE

Using nationwide cancer incidence data, we examined whether the strength of the association of cigarette smoking with lung cancer risk differs according to major histological type and gender, taking account of other risk factors in the Korean population.

METHODS

The study population derived from government employees and teachers aged 20 years and over who participated in a national health examination program in 1998 or 1999. Total study subjects were 1,357,447. After excluding 1556 subjects who were treated with lung cancer during 1998-2000, we restricted our analysis to 1,355,891 cases. We followed up those 1,355,891 subjects who were cancer-free at baseline until December 31, 2010. The incident cancer cases were identified from the Korea Central Cancer Registry, which is a nationwide hospital-based cancer registry system that includes 94 % of the university hospitals and 96 % of the resident training hospitals of the country.

RESULTS

A higher risk for having ever smoked was observed for squamous-cell and small-cell carcinoma in both men and women. Heavy and long-term smokers were at higher risk for these carcinomas. Significant associations with quantity and duration-related factors were observed mainly among men. These findings indicate that smoking is closely related to the risk of squamous-cell and small-cell carcinoma among women as well as men. However, the magnitude of smoking-related lung cancer risk is likely to differ between men and women.

CONCLUSION

The hazard ratios for all types of lung cancer were significantly higher in male current smokers than in male never smokers. In case of women, the hazard ratios for adenocarcinoma were not different between current smokers and never smokers. The hazard ratios we found, however, were lower than those reported in Western countries and in Korea, but consistent with those reported in North-eastern Asian countries.

Lung cancer molecular epidemiology in China: recent trends

Lung cancer is both the most common diagnosed cancer and the leading cause of cancer related deaths in China. During the past three decades, the incidence and mortality of lung cancer in China are increasing rapidly. According to data from National Central Cancer Registry (NCCR) in 2010, the crude incidence of lung cancer in China was 46.08 per 100,000 population (61.86 per 100,000 men and 29.54 per 100,000 women), with an estimated over 600,000 new diagnosed lung cancer patients (416,333 males and 189,613 females). Meanwhile, the crude mortality of lung cancer in China was 37.00 per 100,000 population (50.04 per 100,000 men and 23.33 per 100,000 women). Consistent with the change in developed countries, adenocarcinoma has become the most predominant histological subtype of lung cancer in China. For the majority advanced non-small-cell lung cancer (NSCLC) patients, especially patients with adenocarcinoma, targeted therapy became increasing important in the treatment. Chinese researcher have done a lot work in terms of lung cancer molecular epidemiology, therefore, in this review, we further summarized the epidemiology of driver genes in NSCLC, hoping to help clinicians to better screen certain driver genes in China for treatment decisions.

Establishment and characterization of a singaporean chinese lung adenocarcinoma cell line with four copies of the epidermal growth factor receptor gene

We have established a lung adenocarcinoma cell line, ETCC016, from lung pleural effusion of a male Singaporean Chinese with advanced lung adenocarcinoma. The subject smoked 20 cigarettes per day for more than 30 years. The cell line arose from spontaneous transformation of cells grown in a collagen-coated culture dish. Transformed characteristics of the cell line include the ability to reach high confluency in a culture dish, low cell doubling time, ability to form colonies in soft agar, and ability to form solid tumor in immune-compromised SCID mice. Immunostaining showed that the cells originated from lung epithelial cells. Genomic analysis revealed a large amount of chromosomal aberrations (gain and loss of genetic materials, and loss of heterozygosity [LOH]), indicative of a long history of smoking. The cells have four copies of epidermal growth factor receptor (EGFR) and three copies of MYC, but have lost one copy of the RB1 gene. LOH was detected in TP53 and BRAF genes. There is no anaplastic lymphoma kinase (ALK) gene rearrangement. The ETCC016 lung adenocarcinoma cell line has demonstrated susceptibility towards inhibitors specific for EGFR/HER2 and ALK targets, but resistance to MYC-specific inhibitor. This cell line will be a useful model for further understanding of lung adenocarcinoma.

Cigarette smoking and lung cancer risk according to histologic type in Japanese men and women

Although cigarette smoking is a well-known risk factor for lung cancer, histology-specific risk has not been fully clarified in Japan. This case-control study evaluated the associations between smoking and lung cancer risk according to sex and histologic type. From among patients aged 30 years and over admitted to a single hospital in Japan between 1997 and 2009, 1670 lung cancer cases and 5855 controls were selected. History of smoking, quantity and duration of smoking, and passive smoking from spouses were assessed using a self-administered questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) for each exposure were estimated by unconditional logistic regression. Ever-smoking was significantly associated with a higher risk of squamous cell and small cell carcinoma. The OR for these two histologic types combined was larger in women (OR = 24.98, 95% CI: 13.50-46.23) than in men (OR = 9.43, 95% CI: 5.73-15.51). Analysis of the quantity and duration of smoking showed that the OR for each exposure level tended to be larger in women than in men. For adenocarcinoma, clear positive associations with quantity and duration-related factors were observed among men, and a significant positive association with passive smoking from spouses was found among non-smoking women (OR = 1.44, 95% CI: 1.06-1.95). These results suggest sex- and histologic type- differences in the association of smoking with lung cancer risk. Although smoking control should be continued to prevent lung cancers, further studies are required to better clarify differences in smoking-related lung cancer risk between the sexes and histologic types.

Smoking topography and biomarkers of exposure among Japanese smokers: associations with cigarette emissions obtained using machine smoking protocols

OBJECTIVES

Although the relative risk of lung cancer due to smoking is reported to be lower in Japan than in other countries, few studies have examined the characteristics of Japanese cigarettes or potential differences in smoking patterns among Japanese smokers.

METHODS

To examine tar, nicotine and carbon monoxide (TNCO) emissions from ten leading cigarettes in Japan, machine smoking tests were conducted using the International Organization for Standardization (ISO) protocol and the Health Canada Intense (HCI) protocol. Smoking topography and tobacco-related biomarkers were collected from 101 Japanese smokers to examine measures of exposure.

RESULTS

The findings indicate considerable variability in the smoking behavior of Japanese smokers. On average, puffing behaviors observed among smokers were more similar to the parameters of the HCI protocol, and brands with greater ventilation that yielded lower machine values using the ISO protocol were smoked more intensely than brands with lower levels of ventilation. The smokers of "ultra-low/low" nicotine-yield cigarettes smoked 2.7-fold more intensively than those of "medium/high" nicotine-yield cigarette smokers to achieve the same level of salivary cotinine (p = 0.024). CO levels in expiratory breath samples were associated with puff volume and self-reported smoking intensity, but not with nominal values of nicotine-yield reported on cigarette packages.

CONCLUSIONS

Japanese smokers engaged in "compensatory smoking" to achieve their desired nicotine intake, and levels of exposure were greater than those suggested by the nominal value of nicotine and tar yields reported on cigarette packages.

Role of cigarette filter on the risk of oral cancer: a case-control study in a Chinese population

OBJECTIVE

To determine the role of cigarette filter on the incidence risk of oral squamous cell cancer among male smokers in a Chinese population.

SUBJECTS AND METHODS

A multicentric hospital-based case-control study was applied. Three hundred and nineteen male cases and 428 male controls matching for age ( ± 3 years) were identified from January 2008 to December 2010. Detailed smoking histories were obtained by interviews. Logistic regression model was used to compare the influence of filter and non-filter cigarettes on oral cancer risk.

RESULTS

The adjusted odd ratios (ORs) for oral cancer were 1.30 (95% CI 1.15, 1.48) of filter cigarette smokers, 2.06 (95% CI 1.17, 3.62) of non-filter cigarette smokers, and 1.73 (95% CI 1.33, 2.25) of mixed smokers, as compared with non-smokers. When classified current smokers according to smoking pack year, the ORs of mixed smokers were 2.27 (95% CI 1.06, 4.85) in <20 pack year, 0.81 (95% CI 0.57, 1.14) in 20-39 pack year, and 0.86 (95% CI 0.57, 1.29) in ≥ 40 pack year, as compared to filter cigarette smokers.

CONCLUSIONS

The protective effect against oral cancer of cigarette filter was limited, restricted to smokers of small amount of smoking accumulation. For most smokers, the difference was non-significant between filter and non-filter cigarettes on the risk of developing oral cancer.

Socioeconomic inequalities in incidence of lung and upper aero-digestive tract cancer by age, tumour subtype and sex: a population-based study in Scotland (2000-2007)

BACKGROUND

Lung and upper aero-digestive tract (UADT) cancer risk is associated with socioeconomic inequality (SEI) but the degree of socioeconomic burden by age, tumour subtype, and sex is not known.

METHODS

We reviewed 216,305 cases excluding non melanoma skin cancer (All Cancer) comprising 37,274 lung; 8216 head and neck; and 6534 oesophageal cancers from 2000 to 2007 classified into anatomical or morphology subtypes. Deprivation was measured using the Scottish Index of Multiple Deprivation and SEI was measured using the Slope Index of Inequality and the Relative Index of Inequality (RII). Analyses were partitioned by 5-year age group and sex. RII was adapted to rank tumour type contribution to All Cancer SEI and to examine subtype by age and sex simultaneously. Rank was defined as proportion of All Cancer SEI.

RESULTS

All Cancer SEI was greater for males (RII=0.366; female RII=0.279); the combination of lung and UADT SEI contributed 91% and 81% respectively to All Cancer SEI. For both sexes lung and UADT subtypes showed significant SEI (P<0.001) except oesophageal adenocarcinoma in males (P=0.193); for females, SEI was borderline significant (P=0.048). Although RII rank differed by sex, all lung and larynx subtypes contributed most to All Cancer SEI with RII rank for oral cavity, oesophagus-squamous cell, and oropharynx following. For males 40-44 years, SEI increased abruptly peaking at 55-59 years. For females, SEI gradually peaked 10 years later. In both sexes, the SEI peak preceded peak incidence.

CONCLUSION

SEI in lung and UADT cancers vary greatly by age, tumour subtype and sex; these variations are likely to largely reflect differences between the sexes in risk behaviours which vary by birth cohort and are socioeconomically patterned.

Activated charcoal filter effectively reduces p-benzosemiquinone from the mainstream cigarette smoke and prevents emphysema

In this paper, we have made a comparative evaluation of the cytotoxicity and pathophysiological effects of mainstream smoke from cellulose acetate (CA)-filtered cigarettes with that of charcoal-filtered cigarettes developed in our laboratory. Previously, we had demonstrated that the mainstream smoke from an Indian CA-filtered commercial cigarette contains p-benzosemiquinone (p-BSQ), a major, highly toxic, long-lived water-soluble radical. Here, we have examined 16 brands of different CA-filtered cigarettes including Kentucky research cigarettes, and observed that mainstream smoke from all the cigarettes contains substantial amounts of p-BSQ (100-200 μg/cigarette). We also show that when the CA filter is replaced by a charcoal filter, the amount of p-BSQ in the mainstream smoke is reduced by 73-80%, which is accompanied by a reduction of carbonyl formation in bovine serum albumin to the extent of 70- 90%. The charcoal filter also prevented cytotoxicity in A549 cells as evidenced by MTT assay, apoptosis as evidenced by FACS analysis, TUNEL assay, overexpression of Bax, activation of p53 and caspase 3, as well as emphysematous lung damage in a guinea pig model as seen by histology and morphometric analysis. The results indicate that the charcoal filter developed in our laboratory may protect smokers from cigarette smoke-induced cytotoxity, protein modification, apoptosis and emphysema.

Trends in lung cancer incidence by histological type in Osaka, Japan

Background

In Japan, an increase in age-adjusted incidence rates of lung adenocarcinoma (ADC) and a decrease in lung squamous cell carcinoma (SQCC) have been reported.

Methods

The number of lung cancer incidence, age-adjusted rates, and age-specific rates by birth-cohort according to histological type were examined using the data from Osaka Cancer Registry.

Results

The numbers of lung cancer incidence among men and women have increased, particularly in ADC. The age-adjusted incidence rates of ADC among men and women have continuously increased, while those of SQCC and small cell carcinoma (SMCC) turned to decrease since 1990s. A trough of lung cancer incidence rates was observed among men in 1935–39 birth-cohorts. The declining trend appeared in 1955–59 birth-cohorts. Lung cancer incidence rates among women have increased since 1895–99 birth-cohorts, but those rates leveled off or decreased in 1950s birth-cohorts. Trends of ADC by birth-cohort were almost the same as those of all histological types. The SQCC among men peaked in 1915–19 birth-cohorts, and decreased in the subsequent birth-cohorts. The SMCC among men peaked in 1920s birth-cohorts, and decreased or leveled off in the subsequent birth-cohorts.

Conclusions

Lung cancer incidence rates by birth-cohorts were almost parallel to the smoking prevalence. However, those for ADC among young women in 1950s birth-cohorts were not parallel to the smoking prevalence, which requires careful monitoring to confirm such findings.

Specific Features of Non-small Cell Lung Cancer in Women: A Retrospective Study of 1738 Cases Diagnosed in Bas-Rhin between 1982 and 1997

INTRODUCTION

The literature suggests that lung cancer may represent a different disease in women compared with men and that gender specificities have been reported mostly in clinical trials patients.

METHODS

We conducted a retrospective, population-based study of a sample of 1738 patients diagnosed with a non-small cell lung cancer (NSCLC) in the department of Bas-Rhin (northeastern France) between 1982 and 1997. Our study aimed to describe symptoms at presentation, stage, histological distribution, treatment modalities, and survival, according to sex.

RESULTS

Tobacco exposure differed significantly according to sex: 28.9% of women were nonsmokers versus 1.4% of the men. More NSCLC were metastatic at diagnosis in women than in men (41.1% versus 29.9%). Adenocarcinoma predominated in women (54.4%), whereas squamous cell carcinoma predominated in men (65.9%). Invasive procedures, such as transthoracic needle biopsy, contributed more frequently to histological diagnosis in women. Men and women underwent the same procedures for disease staging, excepted for the abdominal computed tomography scan, which was performed more frequently in women. Treatment also differed: in resectable disease, fewer pneumonectomies were performed in women; in locally advanced disease, the mean doses of thoracic irradiation were significantly lower in women (48.0 grays versus 55.5 grays); in metastatic-stage disease, fewer women received platin-based chemotherapy, but this difference was not significant. Sex was not a significant prognostic factor in our study, contrary to most North American studies, where women seem to have had better survival rates.

CONCLUSIONS

This study emphasizes gender differences in smoking exposure, presentation (stage, histological subtype), and diagnostic and therapeutic management of NSCLC.

Cigarette smoking and primary liver cancer: a population-based case-control study in US men

OBJECTIVE

Using the case-control data from the Selected Cancers Study, the authors assessed whether cigarette smoking increases the risk of primary liver cancer in the US.

METHODS

Cases were men who were pathologically diagnosed with primary liver cancer during 1984-1988, were 31-59 years old, and lived in the areas covered by eight US cancer registries (n=168). Controls were men without a history of primary liver cancer who were selected by random-digit telephone dialing (n=1910).

RESULTS

Relative to non-smokers, the risks of liver cancer were 1.85 (95% confidence interval (CI), 1.05-3.25) and 1.49 (95% CI, 0.83-2.68) for former and current smokers, respectively. The adjusted odds ratio (OR) estimates were 0.96, 1.43, 1.80, and 1.87 for smoking for less than 15, 15-24, 25-34 and 35 or more years, respectively (p for trend=0.039). The OR estimates were 1.41 (95% CI, 0.74-2.68), 1.67 (95% CI, 0.93-2.98), and 1.83 (95% CI, 0.89-3.76) for less than 1, 1-2, and 2 or more packs smoked per day (p for trend=0.068).

CONCLUSIONS

Cigarette smoking may be a factor that contributes somewhat to the occurrence of primary liver cancer among men in the United States, a country with low risk of liver cancer.

Risk factors differ for non-small-cell lung cancers with and without EGFR mutation: assessment of smoking and sex by a case-control study in Japanese

The present study aimed to assess the impact of smoking and sex for the risk of non-small-cell lung cancer (NSCLC) with or without epidermal growth factor receptor (EGFR) mutation. We conducted a case-control study using 152 patients with EGFR-mutated (EGFRmut) NSCLC, 283 with EGFR-wild-type (EGFRwt) NSCLC and 2175 age- and sex-frequency-matched controls. Smoking was a significant risk factor for EGFRwt NSCLC (odds ratio [OR] for ever-smokers, 4.05; 95% confidence interval [CI], 2.79-5.88) but not for EGFRmut NSCLC (OR, 0.73; CI, 0.46-1.14). Sex did not affect this association. The association was observed consistently with other smoking-related parameters including pack-years. Sex was the sole risk factor for EGFRmut NSCLC (OR for women relative to men, 2.19; CI, 1.41-3.39) and there was no significant interaction between women and smoking. In contrast, sex, smoking and their interaction were significant in EGFRwt NSCLC. The impact of sex on EGFR mutation status was assessed by several indicators of reproductive history among women. Total fertile years showed a significant positive association with EGFRmut NSCLC but not with EGFRwt NSCLC. Other indicators showed similar trends and this result may partly explain the sexual difference in the acquisition of EGFR mutation. In conclusion, our case-control study clearly demonstrated that the impacts of smoking and sex on the risk of EGFRmut NSCLC are different from those for EGFRwt NSCLC. Further epidemiological evaluation is warranted.

Influence of smoking charcoal filter tipped cigarettes on various biomarkers of exposure

Charcoal (CC) filters of cigarettes are known to significantly reduce a series of volatile constituents in mainstream smoke, including reactive alpha,beta-unsaturated aldehydes such as acrolein and crotonaldehyde. We performed a randomized, crossover, 2-wk brand-switching study with 39 smokers. Twenty of the subjects smoked cellulose acetate (CA) filter tipped cigarettes during wk 1 of the study; the remaining 19 subjects smoked CC filter tipped cigarettes during wk 1. In wk 2, the subjects switched to the corresponding brand with the other filter type, with similar smoking machine-derived tar and nicotine yields. Daily cigarette consumption, carbon monoxide in exhaled breath, salivary cotinine, and urinary nicotine equivalents (molar sum of nicotine plus five major metabolites) did not change significantly when switching to the cigarettes with the other filter type. Urinary excretion rates of 3-hydroxy-1-methylpropylmercapturic acid (metabolite of crotonaldehyde), monohydroxybutenylmercapturic acid (metabolite of 1,3-butadiene), and S-phenylmercapturic acid (metabolite of benzene) were significantly lower when smoking CC compared to CA filter tipped cigarettes. The reduction in amount of 3-hydroxypropylmercapturic acid (metabolite of acrolein) was of borderline significance. Other mercapturic acids and thioethers (the latter is a summary parameter that indicates the exposure to electrophilic compounds) were not or were only slightly reduced upon smoking CC filter tipped cigarettes. We conclude that smoking CC filter tipped cigarettes does not change the uptake of carbon monoxide and nicotine when compared to CA filter tipped cigarettes with similar tar and nicotine yields, but significantly reduces the exposure to toxicologically relevant smoke constituents such as acrolein, crotonaldehyde, 1,3-butadiene, and benzene.

Socio-economic status and lung cancer risk including histologic subtyping—A longitudinal study

We investigated prospectively the risk of lung cancer in relation to socio-economic status (SES) in 22,387 middle-aged individuals who attended a screening program in the city of Malmö, Sweden between 1974 and 1992. We also examined the relationship between SES and histologic subtype in smokers. By 2003, a total of 550 lung cancer cases had been identified. Relative risks (RR) were calculated with adjustment for age, current smoking, inhalation habits and marital status at baseline in the low SES group compared to high SES group. Among smokers, the RR (95% confidence interval (CI)) for lung cancer in the low SES group of men was 1.39 (1.11-1.73), and women 1.56 (1.04-2.34). Also among smokers, low SES was associated with an increased risk of squamous cell carcinoma in men; RR 1.89 (1.16-2.81) and women; RR 7.10 (1.63-30.86), and with an increased risk of mesothelioma in men RR 9.97 (1.29-76.96). We conclude that low SES groups run an increased risk of lung cancer despite accounting for smoking habits. Furthermore, low SES was positively associated with squamous cell carcinoma and mesothelioma. Our results suggest that the association between low SES and lung cancer could be mediated by unaccounted for smoking exposure, lifestyle or occupational hazards.

Relative and absolute risks of cigarette smoking on major histologic types of lung cancer in Korean men

OBJECTIVES

Most prospective cohort studies of lung cancer focus on the relative risk rather than the absolute risk of smoking.

METHODS

This prospective study included 437,976 Korean men (cohort for the National Health Insurance Cooperation Study), > or = 40 years old, who were free of cancer and smoking-related chronic disease at the time of enrollment. Based on new incidence cases, relative risk and excess risk, and their 95% confidence intervals (95% CI), were estimated with the standard Poisson regression model after adjustment for age or other demographic factors and other confounders.

RESULTS

During the 6-year follow-up period of 3,142,451 person-years, 1,357 new lung cancer cases were identified. Based on the multivariate-adjusted relative risk for current smokers, the strongest association with smoking was shown for small-cell lung cancer (relative risk, 21.7; 95% CI, 8.0-58.5) followed by squamous cell carcinoma (relative risk, 11.7; 95% CI, 7.1-19.4) and then adenocarcinoma (relative risk, 2.1; 95% CI, 1.6-2.7). In current smokers with > or = 40 pack-years of exposure, excess risk was highest for squamous cell carcinoma (excess risk, 33.8; 95% CI, 10.2-109.8) followed by adenocarcinoma (excess risk, 26.7; 95% CI, 10.3-64.4), and then small-cell carcinoma (excess risk, 16.3; 95% CI, 1.8-144.3).

CONCLUSIONS

In Korean men, cigarette smoking was as important a risk factor for adenocarcinoma as it was for squamous cell and small-cell lung cancer.

Charcoal cigarette filters and lung cancer risk in Aichi Prefecture, Japan

The lung cancer mortality rate has been lower in Japan than in the United States for several decades. We hypothesized that this difference is due to the Japanese preference for cigarettes with charcoal-containing filters, which efficiently absorb selected gas phase components of mainstream smoke including the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. We analyzed a subset of smokers (396 cases and 545 controls) from a case-control study of lung cancer conducted in Aichi Prefecture, Japan. The risk associated with charcoal filters (73% of all subjects) was evaluated after adjusting for age, sex, education and smoking dose. The odds ratio (OR) associated with charcoal compared with 'plain' cigarette filters was 1.2 (95% confidence intervals [CI] 0.9, 1.6). The histologic-specific risks were similar (e.g. OR = 1.3, 95% CI 0.9, 2.1 for adenocarcinoma). The OR was 1.7 (95% CI 1.1, 2.9) in smokers who switched from 'plain' to charcoal brands. The mean daily number of cigarettes smoked in subjects who switched from 'plain' to charcoal brands was 22.5 and 23.0, respectively. The findings from this study did not indicate that charcoal filters were associated with an attenuated risk of lung cancer. As the detection of a modest benefit or risk (e.g. 10-20%) that can have significant public health impact requires large samples, the findings should be confirmed or refuted in larger studies.

Predictive factors for epidermal growth factor receptor inhibitors--the bull's-eye hits the arrow

Studies have shown that epidermal growth factor receptor (EGFR) signaling is important to normal development and neoplastic transformation, and that EGFR inhibition reduces cancer cell proliferation. The promising response rates of the EGFR inhibitor gefitinib in patients with chemotherapy-refractory non-small cell lung cancer (NSCLC) led to its approval for clinical use. However, there was little understanding of why gefitinib was effective in only some NSCLC patients. Two recent studies have identified somatic mutations in EGFR that confer its sensitivity to gefitinib in vitro and correlate strongly with patients' clinical response to the inhibitor.