Tar yields of cigarettes and male lung cancer risk

Of 252 male lung cancer patients, 248 or 98% were cigarette smokers, significantly (P less than .001) more than in the control group (526 = 64% of 839). In relation to the relative risks (RR) of never-smokers, the adjusted (for age, total years smoked, and average number of cigarettes smoked per day) lung cancer RR for smokers who had exclusively smoked cigarettes belonging to group II (15-24 mg tar/cigarette) was 10.4 (P less than .001); for smokers who had exclusively smoked cigarettes belonging to group III (greater than 24 mg tar/cigarette), it was 25.1 (P less than .001). The respective RR of smokers who had mainly smoked cigarettes belonging to group I (less than 15 mg tar/cigarette), group II, or group III were 10.9 (P less than .001), 20.6 (P less than .001), and 36.7 (P less than .001). After the differences in daily consumption were taken into account, the adjusted (for age and total years smoked) lung cancer RR for smokers who had consumed mainly cigarettes belonging to the various groups were the following: group II (11-20 cigarettes/day) compared to group III (11-20 cigarettes/day), RR = 0.6 (P less than .05); group II (greater than 20 cigarettes/day) compared to group III (greater than 20 cigarettes/day), RR = 0.8; group II (greater than 20 cigarettes/day) compared to group III (11-20 cigarettes/day), RR = 1.3 (P less than .001); group II (greater than 20 cigarettes/day) compared to group III (less than 10 cigarettes/day), RR = 7.8 (P less than .001); and group II (11-20 cigarettes/day) compared to group III (less than 10 cigarettes/day), RR = 2.5 (P less than .001).     

Use of antidepressants and risk of lung cancer

Objective To evaluate the effect of antidepressant use on lung cancer risk. Methods We conducted a case–control study nested in a cohort of patients 40–84 year-old in 1995–2004, without a prior diagnosis of cancer using The Health Improvement Network (THIN) database in the UK. Cases comprised 4,336 patients with a first diagnosis of primary lung cancer. A sample of 10,000 controls was frequency-matched to the cases for age, sex, and the calendar year of diagnosis. The index date for exposure definition was one year before the diagnosis for cases and one year before a random date for controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression models adjusted for potential confounders. Results Selective serotonin reuptake inhibitor (SSRI) use during the year preceding the index date with treatment duration of at least one year had an OR of 0.59 (95% CI 0.41, 0.86). The corresponding OR was 1.23 (95% CI 0.96, 1.58) for tricyclic antidepressants (TCAs). Conclusions SSRI use did not increase the lung cancer risk and might be associated with a reduced risk. However, residual confounding might explain the apparent protective effect found for SSRI use, as well as the marginally elevated risk observed among TCA users.     

Tar yields of cigarettes and the risk of oesophageal cancer

The relationship between cigarettes with varying tar yields and the risk of oesophageal cancer was evaluated using data from a hospital-based case-control study conducted in Northern Italy on 129 histologically confirmed cases and 426 controls with acute, non-neoplastic of digestive diseases unrelated to tobacco or alcohol consumption. Compared with never-smokers, the relative risks of developing cancer of the oesophagus were 2.9 for subjects who smoked mainly middle- or low-tar (less than 22 mg) cigarettes and 8.9 for those smoking high-tar cigarettes (greater than or equal to 22 mg). The difference between the two categories was evident among ever-smokers and only current smokers, was not explained by adjustment for the major covariates of interest (social class, alcohol consumption and dietary indicators), and persisted when allowance was made for duration of smoking and number of cigarettes smoked per day by means of multiple regression analysis. The present findings suggest that the relation between tar deliveries of cigarettes and risk may be even more marked for oesophageal than for lung cancer. Further, they have important public health implications, in consideration of the current relatively high tar yields of Italian cigarettes, particularly in a few areas of north-eastern Italy where death certification rates from cancer of the oesophagus are among the highest in Europe. Nonetheless, in this study, smokers of prevalently low- to mid-tar cigarettes still did experience a significantly higher oesophageal cancer risk than life-long non-smokers.     

Use of electronic cigarettes among African American cancer survivors

Background

The use of electronic cigarettes (e-cigarettes) is increasing rapidly in the United States, although the negative health outcomes associated with these products are still unknown. Emerging research has examined the use of e-cigarettes in the cancer survivor population as a whole, yet none has focused on e-cigarette use in the African American (AA) cancer survivor population.

Methods

The authors used data from the Detroit Research on Cancer Survivors cohort study, comprised of AA adult cancer survivors. Logistic regression models were used to evaluate factors potentially associated with e-cigarette ever use and current use.

Results

Of 4443 cancer survivors who completed a baseline interview, 8.3% (n = 370) reported ever using e-cigarettes, and 16.5% (n = 61) of those reporting ever use also reported current use of e-cigarettes. Ever users and current users were on average younger than those who did not use e-cigarettes (57.5 vs. 61.2 years; p < .001). Current cigarette smokers were >20 times more likely (odds ratio, 20.75; 95% confidence interval, 12.84–33.55) and former smokers were almost 10 times more likely (odds ratio, 9.50; 95% confidence interval, 6.03–14.97) to have ever used e-cigarettes than never-smokers. Preliminary data suggested that ever use of e-cigarettes is associated with later stage at diagnosis for breast and colorectal cancers.

Conclusions

As the use of e-cigarettes increases in the general population, it is important to continue to monitor their use in cancer survivors and to gain more insight as it pertains to the AA cancer survivor population. Elucidation of the factors associated with e-cigarette use in this population may help inform comprehensive cancer survivorship recommendations and interventions.     

Use of lung cancer risk models in planning research and service programs in CT screening for lung cancer

Computed tomography screening for lung cancer is now being tested in a number of international trials. The long-term success of the approach in the future National Screening Programme is dependent upon identifying populations at sufficient risk of lung cancer that the benefit–harm ratio of the intervention is likely to be high. There are a number of lung cancer risk prediction models currently available. We review these, and demonstrate, using the Liverpool Lung Project risk prediction model as a case study, the potential for use of a risk prediction model in the design of a randomized trial of lung cancer screening and in the planning of a service screening program.     

Chlamydia pneumoniae infection and risk of lung cancer.

Infection with Chlamydia pneumoniae may be associated with an increased risk of lung cancer. We conducted a matched case-control study (508 pairs) nested within a large prospective study to investigate whether IgA antibody titers to C. pneumoniae measured by the microimmunofluorescence test are associated with lung cancer risk after controlling for confounders. Individuals with antibody titers > or = 16 had 1.2 times the risk of lung cancer (95% confidence interval, 0.9-1.6) compared to those with lower titers. There was a significant trend (P = 0.007) of increasing odds ratios with increasing IgA titers primarily due to an odds ratio of 2.8 (95% confidence interval, 1.1-6.7) associated with titers > or = 256. Lung cancer risk associated with IgA titers > or = 16 was stronger among former smokers. To better understand predictors of IgA seropositivity, we also examined demographic, lifestyle, dietary, and medical correlates of IgA titers > or = 16 among controls. Those with race not classified as White or Black were more likely to have IgA titers > or = 16; there were no significant differences in seropositivity by smoking behaviors. In summary, the adjusted odds ratio for lung cancer associated with IgA titers > or = 16 was compatible with a weakly positive association, although nondifferential measurement error of antibody titers may have resulted in a conservative bias. Future studies using precise measures of chronic C. pneumoniae status are needed to better determine the role of this organism in the etiology of lung cancer.     

The leukocyte count and risk of lung cancer.

The association between leukocyte count and subsequent risk of lung cancer was evaluated in three large cohorts from the United States and Britain. A total of 309 lung cancer events occurred among 28,181 men whose cases were followed-up for 7 to 12 years. In all three cohorts, there was a marked increase in risk of lung cancer with increasing leukocyte count, after adjustment for age and the number of cigarettes smoked per day. The adjusted relative odds in the three cohorts, for a 2000/microliters difference in leukocyte count, were 1.58 (P = 0.0001), 1.29 (P = 0.003) and 1.20 (P = 0.02). These relative odds persisted when current smokers were considered alone, when serum markers of cigarette smoking exposure were adjusted for, and when men with lung cancer events during the first 5 years of follow-up were excluded. The leukocyte count appears to be linked to the pathogenesis of smoking-related lung cancer.     

Volatile nitrosamines and tobacco-specific nitrosamines in the smoke of Thai cigarettes: a risk factor for lung cancer and a suspected risk factor for liver cancer in Thailand

In Thailand, smoking of commercial cigarettes and of handmadecigarettes has drastically increased in recent decades. Cancerof the lung and of the upper aerodigestive tract have also increasedin Thailand as they have in many other countries. It is ourworking hypothesis that the increase of primary cancer of theliver, especially of cholangiocarcinoma in the north-easternprovinces of Thailand is associated with the use of tobaccoin men infested with the liver fluke Opisthorchis viverrini(OV). Bioassays have shown that volatile nitrosamines and tobacco-specificnitrosamines induce cholangiocarcinoma in laboratory animalsand that the hepatocarcinogenic action of nitrosodimethylaminein hamsters is significantly increased by infestation with theliver fluke OV. The endogenous formation of nitrosamines issignificantly increased by OV infestation. This report presentsanalytical data on the concentration of volatile nitrosaminesand tobacco-specific nitrosamines in mainstream smoke of nineleading brands of commercially produced Thai cigarettes whichrepresent ~85% of the market share in Thailand. Observed ranges(ng/cigarette) were 8.5–31.9 for nitrosodimethylamine,8.8–49.6 for nitrosopyrrolidine and 4.2–18.9 fornitrosodi-n-butylamine. These values are exceptionally highcompared with the smoke of light and blended cigarettes fromNorth America and Western Europe. Among the tobacco-specificnitrosamines, the range was 28–730 for nitrosonornicotineand 16–370 for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.There was a correla-tion between volatile and tobacco-specificnitrosamines, and tar and nicotine deliveries in the mainstreamsmoke. The analytical data are in line with the rate for lungcancer and support our working hypothesis that nitrosamines,and especially the tobacco-specific nitrosamines, are associatedwith the increased risk for primary liver cancer among thoseThai people who smoke cigarettes and also carry OV infestation.     

Maternal lung cancer and testicular cancer risk in the offspring.

It has been hypothesized that smoking during pregnancy could increase the offspring's risk for testicular cancer. This hypothesis is indirectly supported by both ecological studies and studies of cancer aggregations within families. However, results from analytical epidemiological studies are not consistent, possibly due to methodological difficulties. To further study the association between smoking during pregnancy and testicular cancer, we did a population-based cohort study on cancer risk among offspring of women diagnosed with lung cancer. Through the use of the Swedish Cancer Register and the Swedish Second-Generation Register, we identified 8,430 women who developed lung cancer between 1958 and 1997 and delivered sons between 1941 and 1979. Cancer cases among the male offspring were then identified through the Swedish Cancer Register. Standardized incidence ratios were computed, using 95% confidence intervals. We identified 12,592 male offspring of mothers with a subsequent diagnosis of lung cancer, and there were 40 cases of testicular cancer (standardized incidence ratio, 1.90; 95% confidence interval, 1.35-2.58). The association was independent of maternal lung cancer subtype, and the risk of testicular cancer increased stepwise with decreasing time interval between birth and maternal lung cancer diagnosis. Our results support the hypothesis that exposure to cigarette smoking in utero increases the risk of testicular cancer.     

Asthma and risk of lung cancer

Asthma is a very common chronic disease that occurs in all age groups. Its high prevalence has significant health costs, which are even higher in the most severe disease forms. Lung cancer has the highest incidence of all cancers in the developed world and is an important cause of mortality. Patients with lung cancer are a big economic burden on health services, both in direct and indirect costs. Different authors suggest that atopic constitution, including different manifestations of allergy and asthma, are possible risk factors for lung cancer, above all in never-smokers. Given the high asthma prevalence and lung cancer incidence and mortality in developed countries, this association would have important public health implications. Uncertainties about the association and the underlying physiopathological mechanisms, however, seem to require further studies.     

Dietary habits and lung cancer risk

A previously reported negative association between a high index of dietary vitamin A and lung cancer incidence was confirmed in an extended follow-up, covering 11 1/2 years, of 13,785 men and 2,928 women. Responses to a postal questionnaire provided the dietary information. Relationships between the major dietary items and lung cancer were explored for various diagnostic subsets of the 168 lung cancer cases diagnosed among the study subjects. Analyses were stratified for sex, age, residence characteristics, cigarette smoking and, at times, socioeconomic group. Although the data do not permit a firm interpretation in terms of risk enhancement by a marginal retinoid deficiency, we found that the apparent protection afforded by higher intakes of vitamin A or its provitamins was particularly strong for lung cancer appearing as squamous-cell carcinoma and among those with higher alcohol intakes. The individual food items which showed the strongest negative association with lung cancer were carrots and milk. These two items made a major contribution to the vitamin A index and its variation among the respondents.     

XPC polymorphisms and lung cancer risk

Polymorphisms in DNA repair genes may be associated with differences in the capacity to repair DNA damage and thereby influence an individual's susceptibility to smoking-related cancer. To test this hypothesis, we investigated the potential association of 7 XPC polymorphisms (-449G-->C, -371G-->A, -27G-->C, Val499Arg, PAT-/+, IVS11-5C-->A and Lys939Gln) and their haplotypes with lung cancer risk in a Korean population. XPC genotypes were determined in 432 lung cancer patients and 432 healthy controls frequency-matched for age and sex. XPC haplotypes were predicted using a Bayesian algorithm in the Phase program. The combined -27CG+CC genotype was associated with a significantly increased risk for overall lung cancer compared to the -27GG genotype (adjusted OR = 1.97, 95% CI 1.22-3.17, p = 0.005). The other 6 polymorphisms were not significantly associated with overall risk of lung cancer. When lung cancer cases were categorized by tumor histology, the -371AA genotype was associated with a significantly increased risk of squamous cell carcinoma compared to the combined -371GG and GA genotype (adjusted OR = 2.08, 95% CI 1.09-4.00, p = 0.03). The PAT-/+, IVS11-5C-->A and Lys939Gln polymorphisms were associated with a significantly decreased risk of small cell carcinoma (SM) under a dominant model for the polymorphic allele (adjusted OR = 0.49, 95% CI 0.29-0.82, p = 0.006; adjusted OR = 0.60, 95% CI 0.36-1.00, p = 0.05; and adjusted OR = 0.58, 95% CI 0.35-0.97, p = 0.04, respectively). Consistent with genotyping analyses, haplotype 4 (1112222) containing the PAT+/IVS11-5A/939Gln alleles was associated with a significantly decreased risk of SM (adjusted OR = 0.56, 95% CI 0.37-0.85, p = 0.007 and Bonferroni-corrected p = 0.049), whereas haplotype 5 (1122111) containing the -27C allele was associated with a significantly increased risk of SM (adjusted OR = 2.88, 95% CI 1.41-5.87, p = 0.004 and Bonferroni-corrected p = 0.028). These results suggest that XPC polymorphisms/haplotypes may contribute to genetic susceptibility for lung cancer.     

Occupational exposure and lung cancer risk

The importance of occupation held longest as a risk factor for lung cancer was examined in a prospective study in Norway of 11,995 men, among whom 125 cases occurred in a follow-up from 1966 through 1978. Based on information about occupation held longest, the respondents were classified into 3 groups according to suspected exposure to respiratory carcinogens at the workplace. After stratification for age, place of residence and cigarette smoking, we found a highly significant relative risk of 2.6 for those judged to have experienced definite exposure versus the group with no workplace exposure. The apparent risk-enhancing effect of occupational exposure was observed for all histologic subtypes. Stratification including a socioeconomic factor score led to a moderate reduction in the relative risk estimate. High risk estimates still obtained, however, for a limited number of occupations, the highest for workers in the mining and quarrying industries. Although the interpretation of the observed effect associated with a crude index of occupational exposure may be difficult, our results suggest that between 13 and 27% of the lung cancer cases observed among Norwegian men in the relevant time period can be attributed to harmful work-place exposure.