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.     

Polymorphism of the DNA repair gene XRCC1 and risk of primary lung cancer.

DNA repair plays a critical role in protecting the genome of the cell from insults of cancer-causing agents, such as those found in tobacco smoke. Reduced DNA repair capacity, therefore, can increase the susceptibility to smoking-related cancers. Recently, three coding polymorphisms in X-ray cross-complementing group 1 (XRCC1) DNA repair gene have been identified, and it is possible that these polymorphisms may affect DNA repair capacity and thus modulate cancer susceptibility. We investigated the relationship between the codon 399 polymorphism in XRCC1 gene and lung cancer risk in male smokers. The study population consisted of 192 lung cancer patients and 135 healthy controls. The distribution of XRCC1 genotypes was not significantly different between cases and controls. When the cases were categorized by histological type, however, the presence of at least one Gln allele was associated with a significant increased risk for squamous cell carcinoma [crude odds ratio (OR) = 1.77, 95% confidence interval (CI) = 1.06-2.93 and adjusted OR = 1.66, 95% CI = 0.99-2.79]. The risk for the disease increased as the number of Gln alleles increased (Arg/Gln genotype: adjusted OR = 1.45, 95% CI = 0.84-2.5; Gln/Gln genotype: adjusted OR = 3.26, 95% CI = 1.17-9.15). When the subjects dichotomized by cigarette consumption into two pack-year groups (< or =40 pack-years, >40 pack-years), the Gln allele was associated with an increased risk for squamous cell carcinoma only in the group of individuals having < or =40 pack-years of smoking (Arg/Gln genotype: adjusted OR = 1.48, 95% CI = 0.78-2.8; Gln/Gln genotype: adjusted OR = 5.75, 95% CI = 1.46-22.69). These results suggest that XRCC1 codon 399 polymorphism may be an important genetic determinant of squamous cell carcinoma of the lung in persons with lower degrees of cigarette use.     

-93G-->A polymorphism of hMLH1 and risk of primary lung cancer

Polymorphisms in DNA repair genes may be associated with differences in the repair capacity of DNA damage and may thereby influence an individual's susceptibility to smoking-related cancer. We investigated the association between the -93G-->A polymorphism in the hMLH1 gene and the risk of lung cancer in a Korean population. The hMLH1 -93G-->A polymorphism was typed in 372 lung cancer patients and 371 healthy controls that were frequency-matched for age and sex. There was no significant association between the hMLH1 -93G-->A genotype and the risk for adenocarcinoma or small cell carcinoma. However, the AA genotype was associated with a significantly increased risk for squamous cell carcinoma compared with both the GG genotype (adjusted OR=2.02; 95% CI=1.15-3.55; p=0.014) and the combined GG and GA genotype (adjusted OR=1.83; 95% CI=1.24-2.71; p=0.003). When the subjects were stratified by smoking exposure, the AA genotype was associated with a significantly increased risk for squamous cell carcinoma in lighter smokers (< or = 39 pack-years; adjusted OR=1.95; 95% CI=1.03-3.66; p=0.039) compared with the combined GG and GA genotype, whereas there was no significant association in heavier smokers (> 39 pack-years; adjusted OR=1.47; 95% CI=0.82-2.61). These results suggest that the hMLH1 -93G-->A polymorphism could be used as a marker of genetic susceptibility to squamous cell carcinoma of the lung.     

The TP53 Arg72Pro polymorphism and lung cancer risk in a population of Northern Spain

Polymorphisms in tumor suppressor genes might contribute to the individual susceptibility to develop different types of cancer. Alterations in genes involved in cell cycle regulation and apoptosis, as tumor suppressor gene TP53, can lead to malignant transformations increasing the risk of developing cancer. We have investigated effects of polymorphism Arg72Pro on lung cancer risk, focusing on smoking and histology. Our study is a hospital-based case-control study designed with 589 lung cancer patients mainly with squamous cell carcinoma (215), adenocarcinoma (156) and small cell carcinoma (90), and 582 control subjects, matched in ethnicity, age and gender. Genotypes were determined by PCR-RFLP and the results were analysed using multivariate unconditional logistic regression, adjusted for age, gender and smoking status. The analysis showed a statistically significant increase of lung cancer risk in Pro carriers (Arg/Pro and Pro/Pro) (adjusted OR=1.32; 95% CI=1.03-1.69), especially for ever smokers (adjusted OR=1.34; 95% CI=1.04-1.73), heavy smokers (adjusted OR=1.48; 95% CI=1.01-2.16) and smokers of exclusively black tobacco (adjusted OR=1.45; 95% CI=1.04-2.00). Moreover, Pro carriers present an increased risk of developing small cell lung cancer (adjusted OR=1.70; 95% CI=1.07-2.69) and cancer in stage IV for NSCLC (adjusted OR=1.56; 95% CI=1.07-2.27). Our results suggest that polymorphism Arg72Pro in tumor suppressor gene TP53 increases the risk of lung cancer. The effect is especially strong for small cell lung cancer (SCLC) and heavy smokers.     

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.     

Aryl hydrocarbon receptor gene polymorphisms affect lung cancer risk

To evaluate the role of genetic polymorphisms of AhR related to the carcinogen metabolism and cell proliferation, genotypes of three AhR polymorphisms Ex1+185A>G, IVS7+33T>G and Ex10+501G>A were determined in 616 lung cancer cases and 616 lung cancer-free controls. When the effect of each AhR allele on lung cancer risk was evaluated, any AhR genotype did not show the association with lung cancer risk. However, when haplotypes were composed of three AhR SNP sites, non-smokers with GGG haplotype (adjusted OR=1.7, 95% CI, 1.06-2.71) and smokers without GGG haplotype (adjusted OR=2.5, 95% CI, 1.64-3.74) showed significantly increased risk of lung cancer compared to non-smokers without GGG haplotype. Moreover, smokers with GGG haplotype showed the highest risk (adjusted OR=3.2, 95% CI, 2.10-4.74). Particularly, the synergistic effect between AhR haplotype and smoking was more apparent in squamous cell carcinoma (adjusted OR=6.1, 95% CI, 2.53-14.68). This result suggests that haplotypes of AhR gene play an important role in the development of lung cancer and there is a synergistic interaction between AhR gene and smoking for lung cancer risk.     

中国人食管癌及肺癌发病风险与p53基因多态性

目的　比较中国北方人对食管癌及肺癌的易感性与p5 3基因第 72密码子多态性的关系。方法　应用序列特异性引物 ,以PCR方法检测 173例食管鳞状上皮癌、98例非小细胞肺癌患者及 136例健康对照者的p5 3基因第 72密码子的基因型。结果　食管癌与肺癌组p5 3等位基因及基因型分布无明显差异。食管癌和肺癌组的Pro等位基因频率明显高于对照组 (P值分别为 0 .0 2 4及0 .0 2 7)。Pro/Arg及Arg/Arg基因型频率在两肿瘤组及对照组差异无显著性 (P >0 .0 5 ) ,而食管癌和肺癌组的Pro/Pro基因型频率明显高于对照组 (P值分别为 0 .0 4 1及 0 .0 2 6 )。Pro纯合子患食管癌与肺癌的风险较Arg纯合子高 2倍左右 [校正比值比分别为 2 .12 (95 %CI=1.13～ 4 .0 1)和 2 .30 (95 %CI =1.13～ 4 .93) ],且与吸烟无协同作用。结论　Pro/Pro基因型为中国北方人患食管癌及肺癌的独立易感因素 ,两种肿瘤的发病可能有共同的遗传基础。     

GSTM1, GSTT1 and GSTP1 polymorphisms and lung cancer risk

Previous studies have suggested that GST genotypes may play a role in determining susceptibility to lung cancer, though the data are often conflicting. In this study we investigated GSTM1, GSTT1 and GSTP1 status in relation to lung cancer risk in patients attending a Manchester bronchoscopy clinic. Cases were all patients (n=94) currently with, or with a history of, tumours of the lung, trachea or bronchus. The control group were all other patients (n=165) who were free of benign and malignant tumours both at the time of, or prior to, diagnosis. All patients were interviewed for information on lifestyle risk factors, and DNA extracted from bronchial lavage and blood samples was used for genotyping. GSTM1 null genotype was associated with decreased lung cancer risk (odds ratio (OR) 0.50, 95% confidence interval (CI) 0.29–0.87), particularly among men (OR 0.43, 95% CI 0.21–0.87) and those above the median age (OR 0.33, 95% CI 0.15–0.70). No difference in GSTT1 and GSTP1 genotype distribution was seen between cases and controls. The GSTM1 null genotype was associated with a decreased risk of squamous cell carcinoma: the OR, adjusted for age, sex and pack years was 0.32 (95% CI 0.12–0.82). As previous studies have reported that the GSTM1 null genotype is associated with an increased lung cancer risk, further work is required to determine whether the observed association is true, or whether it arises from bias or confounding factors.     

Association of the hOGG1 Ser326Cys Polymorphism with Increased Lung Cancer Susceptibility in Asians: a Metaanalysis of 18 Studies Including 7592 Cases and 8129 Controls

Objective: To understand the influence of the hOGG1 Ser326Cys polymorphism on lung cancer susceptibility,an updated meta-analysis was performed. Methods: A total of 7,592 patients and 8,129 controls from 18 studies,identified by searching ISI Web of Knowledge, PubMed, EMBase and CNKI database up to January 2011,were included. Unconditional multivariable logistic regression was used to estimate odds ratios (ORs) and 95%confidence intervals (CIs). Results: Overall, the hOGG1 Ser326Cys polymorphisms were associated with the riskof lung cancer. In the subgroup analyses by ethnicity, histological type, smoking status, significant associationwith lung cancer risk in Asians was found either in the dominant (crude OR, 1.19; 95% CI, 1.07-1.33 for Cys/Cys+Ser/Cys versus Ser/Ser) or recessive (crude OR, 1.21; 95% CI, 1.08-1.35 for Cys/Cys versus Ser/Cys+Ser/Ser) model. An increased risk with statistical significance was found in recessive model for squamous carcinoma(adjusted OR, 1.91; 95% CI, 1.30-2.80) and adenocarcinoma (adjusted OR, 1.52; 95% CI, 1.23-1.87). Significantassociation with lung cancer risk among heavy smokers was found in the recessive model (crude OR, 1.67; 95%CI, 1.26-2.21). Conclusions: The results indicated that the hOGG1 Ser326Cys polymorphism might contributeto the risk of non-small cell lung cancer in the Asian population.     

Family history of cancer and nonmalignant lung diseases as risk factors for lung cancer

Family history (FH) of lung cancer is an established risk factor for lung cancer, but the modifying effect of smoking in relatives has been rarely examined. Also, the role of FH of nonmalignant lung diseases on lung cancer risk is not well known. We examined the role of FH of cancer and nonmalignant lung diseases in lung cancer risk overall, and by personal smoking, FH of smoking and histology in 1,946 cases and 2,116 population‐based controls within the E nvironment A nd G enetics in L ung cancer E tiology (EAGLE) study. Odds ratios (ORs) and 95% CI from logistic regression were calculated adjusting for age, gender, residence, education and cigarette smoking. FH of lung cancer in any family member was associated with increased lung cancer risk (OR = 1.57, 95% CI = 1.25–1.98). The odds associated with fathers', mothers' and siblings' history of lung cancer were 1.41, 2.14 and 1.53, respectively. The associations were generally stronger in never smokers, younger subjects and for the adenocarcinoma and squamous cell carcinoma subtypes. FH of chronic bronchitis and pneumonia was associated with increased (OR = 1.49, 95% CI = 1.23–1.80) and decreased (OR = 0.73, 95% CI = 0.61–0.87) lung cancer risk, respectively. FH of lung cancer and nonmalignant lung diseases affected lung cancer risk independently, and did not appear to be modified by FH of smoking. © 2009 UICC     

Relationship between XPG codon 1104 polymorphism and risk of primary lung cancer

DNA repair plays a critical role in protecting the genome from insults of cancer-causing agents, such as those found in tobacco smoke. Therefore, reduced DNA repair capacity can increase the susceptibility to smoking-related cancers. Recently, several polymorphisms have been identified in the xeroderma pigmentosum group G (XPG) gene, and it is possible that these polymorphisms may affect the DNA repair capacity, thereby modulating cancer susceptibility. We investigated the relationship between the His1104Asp polymorphism in the XPG gene and the risk of lung cancer. The study population consisted of 310 lung cancer patients and 311 healthy controls who were frequency (1:1) matched based on age and sex. The Asp/Asp genotype was more frequent in the controls (28.9%) than in the cases (18.7%) and associated with a significantly decreased risk of lung cancer [adjusted odds ratio (OR) = 0.54, 95% confidence interval (CI) = 0.37-0.80] when the combined His/His and His/Asp genotype was used as the reference. The protective effect of the Asp/Asp genotype against lung cancer was statistically significant in the older subjects (adjusted OR = 0.51, 95% CI = 0.37-0.80), males (adjusted OR = 0.54, 95% CI = 0.35-0.83), and lighter smokers (adjusted OR = 0.48, 95% CI = 0.25-0.94) in a stratification analysis. When the lung cancers were analyzed by histologic type, the Asp/Asp genotype was associated with a significantly decreased risk of squamous cell carcinoma (adjusted OR = 0.55, 95% CI = 0.34-0.88) and small cell lung cancer (adjusted OR = 0.44, 95% CI = 0.20-0.97), but non-significant decreased risk of adenocarcinoma (adjusted OR = 0.64, 95% CI = 0.36-1.12). These results suggest that the XPG codon 1104 polymorphism contributes to genetic susceptibility to lung cancer.     

尿苷二磷酸葡糖醛酸转移酶1A7基因多态与肺癌遗传易感性的关系

背景与目的:代谢酶尿苷二磷酸葡糖醛酸转移酶1A7(UDP-glucuronosyltcansferase,UGT1A7)可催化香烟中的致癌物质苯并[琢]芘、亚硝胺NNK和杂环胺PhIP与葡糖醛酸结合使之失活,在解毒机制中起重要作用。本实验旨在研究UGT1A7基因多态与肺癌易感性的关系。方法:以聚合酶链反应-变性高效液相色谱(DHPLC)技术和聚合酶链反应-限制性片段长度多态性方法,分析317例正常对照和312例肺癌患者外周血淋巴细胞基因组DNA,UGT1A7129～131和208位点多态基因型分布,及其与肺癌风险的关系。结果:与携带UGT1A7*1/*1基因型个体比较,携带UGT1A7*3/*1基因型的个体患肺腺癌的风险增高1.80倍(校正的OR为1.80;95%CI1.03～3.12),携带UGT1A7*3基因型的个体患肺腺癌的风险增高1.59倍(校正的OR为1.59,95%CI0.96～2.63)。UGT1A7多态与肺鳞癌风险不相关。结论:UGT1A7基因多态可能是中国人肺癌遗传易感性因素。     

髓过氧化物酶基因-463G/A多态与中国人肺癌遗传易感性

目的 研究髓过氧化物酶（MPO）基因－463G→A单核苷酸多态与肺癌易感性的关系。方法 以PCR－单链构像多态（SSCP）技术,分析了314例肺癌患者和320例正常对照者MPO基因启动子区第－463位核苷酸多态基因型分布,及其与肺癌风险的关系。结果 正常对照组中G和A等位基因频率分别为85.0%和15.0%,而肺癌患者分别为89.0%和11.0%。携带MPO－463GG基因型的个体患肺癌风险比携带GA和AA基因型个体高1.7倍（校正的OR为1.7;95%CI为1.2-2.5）,且此种风险增高只限于肺鳞癌（OR为2.4;95%CI为1.4-3.9）,而与肺腺癌无关（OR为1.3;95%CI为0.8-2.1）。分层分析结果表明,与GA和AA基因型比较,GG基因型并不增加非吸烟者和累积吸烟量＜26包年者患肺癌的风险,但在累积吸烟量≥26包年的吸烟者中,GG基因型发生肺鳞癌的风险比GA和AA基因型高3.3倍。结论 MPO－463 A等位基因显著降低中国人发生吸烟相关性肺鳞癌的风险。     

Cigarette smoking and subsequent risk of lung cancer by histologic type in middle-aged Japanese men and women: the JPHC study

In order to update the findings of relative risk associated with cigarette smoking for lung cancer by histologic type in Japan, the data from a population-based cohort study of 91,738 men and women were analyzed. During 1990-1999, 422 lung cancer incident cases were identified. The relative risk for all incident cases associated with current smokers versus non-smokers was 4.5 [95% confidence interval (CI): 3.0-6.8] and 4.2 (95% CI: 2.4-7.2), for men and women, respectively. When divided by histologic type, relative risk for squamous cell carcinoma and small cell carcinoma was 12.7 (95% CI: 4.7-34.7) and 17.5 (95% CI: 4.9-62.1), while for adenocarcinoma it was 2.8 (95% CI: 1.6-4.9) and 2.0 (95% CI: 0.8-5.0) for men and women, respectively. We confirmed that the lung cancer risk in men rose with increasing cigarette smoking, especially the duration of smoking among current smokers and decreased after the cessation of smoking among former smokers. Unlike the US or European countries, the relative risk did not increase in this updated study, compared with previous studies in 1960s to 1990s in Japan either for all incident cases or for specific histologic types and the magnitude of relative risks was substantially lower than that observed in the US or European countries, especially for adenocarcinoma.     

Small cell lung cancer in women: risk associated with smoking, prior respiratory disease, and occupation

Small cell carcinoma of the lung (SCLC) occurs most frequently in heavy smokers, yet exhibits a lesser predominance among men than other smoking-associated lung cancers. Incidence rates have increased more rapidly in women than men and at a faster rate among women than other cell types. To investigate the importance of smoking and other risk factors, a case-control study of SCLC in women was conducted. A total of 98 women with primary SCLC and 204 healthy controls, identified by random-digit dialing and frequency matched for age, completed telephone interviews. Data collected include demographics, medical history, family cancer history, residence history, and lifetime smoking habits. Odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated using logistic regression analysis. Risk for small cell carcinoma in women is strongly associated with current use of cigarettes. Ninety-seven of 98 cases had smoked cigarettes; 79% of cases were current smokers and 20% were former smokers at the time of diagnosis compared to 13% current and 34% former smokers among controls. The ORs associated with smoking are 108.7 (95% CI 14.8-801) for ever-use of cigarettes, 278.9 (95% CI 37.0-2102) for current smoking, and 31.5 (95% CI 4. 1-241) for former smoking. Risk increases steeply with pack-years of smoking and decreases with duration of smoking cessation. After adjusting for age, education, and lifetime smoking history, medical history of physician-diagnosed respiratory disease including chronic bronchitis, emphysema, pneumonia, tuberculosis, asthma, and hay fever is not associated with a significant increase in lung cancer risk. Employment in blue collar, service, or other high risk occupations is associated with a two to three-fold non-significant increase in risk for small cell carcinoma after adjusting for smoking.     

Oral disease and risk of oesophageal and gastric cancer in a nationwide nested case-control study in Sweden

The association between the exposure to oral disease and the outcomes of oesophageal and gastric cancer was examined in a Swedish nationwide inpatient register-based nested case-control study in 1964-2008. The study included 6,156 oesophageal squamous-cell carcinoma cases that were compared with 29,993 controls, 2684 oesophageal adenocarcinoma cases that were compared with 15,036 controls and 38,308 gastric cancer cases that were compared with 99,991 controls. For oesophageal squamous cell carcinoma, the age and sex adjusted odds ratio (OR) among patients with a history of oral disease was 1.3 (95% confidence interval (95% CI): 0.9,−1.9), and 1.1 (95% CI 0.8,−1.7) after adjustment for diseases related to alcohol consumption or tobacco smoking. For oesophageal adenocarcinoma, the age and sex adjusted OR was increased (OR 1.7, 95% CI 1.1-2.6), and remained increased (OR 1.6, 95% CI 1.0-2.4) after adjustment for diseases related to smoking or alcohol consumption, gastroesophageal reflux, obesity and ulcer disease. For gastric cancer, no statistically significantly increased risk was observed (age and sex adjusted OR 0.9, 95% CI 0.7-1.1, and fully adjusted OR 0.9, 95% CI 0.7-1.1). In conclusion, this study supports the hypothesis that oral disease increases the risk of oesophageal adenocarcinoma, but not for oesophageal squamous cell carcinoma or gastric cancer. Further investigations are warranted.     

Cancer in the respiratory organs of Swedish farmers

In a cohort of 254,417 male Swedish farmers (4,330,717 person-years) the incidence of cancer of the respiratory organs was compared to a reference cohort of 1,725,845 men (30,131,664 person-years) employed in other economic activities than agriculture or forestry. In the study cohort 1450 cases of cancer in the respiratory organs were found in 1961 to 1979 resulting in an estimated relative risk (RR) of 0.38 (95% confidence interval [CI]: 0.36-0.40). For cancer of trachea, bronchus and lung, the decreased risk was equal for adenocarcinoma and squamous cell carcinoma. No time related trend in RR for any of the histologic subtypes could be seen. However, for squamous cell carcinoma in nose and nasal sinuses RR has increased from 0.42 (95% CI: 0.20-0.80) in 1961 to 1966 to 2.06 (95% CI: 1.22-3.50) in 1974 to 1979.     

Lung Cancer Inequalities in Stage of Diagnosis in Ontario,Canada

Lung cancer is the most common cancer and cause of cancer death in Canada, with approximately 50% of cases diagnosed at stage IV. Sociodemographic inequalities in lung cancer diagnosis have been documented, but it is not known if inequalities exist with respect to immigration status. We used multiple linked health-administrative databases to create a cohort of Ontarians 40–105 years of age who were diagnosed with an incident lung cancer between 1 April 2012 and 31 March 2017. We used modified Poisson regression with robust standard errors to examine the risk of diagnosis at late vs. early stage among immigrants compared to long-term residents. The fully adjusted model included age, sex, neighborhood-area income quintile, number of Aggregated Diagnosis Group (ADG) comorbidities, cancer type, number of prior primary care visits, and continuity of care. Approximately 62% of 38,788 people with an incident lung cancer from 2012 to 2017 were diagnosed at a late stage. Immigrants to the province were no more likely to have a late-stage diagnosis than long-term residents (63.5% vs. 62.0%, relative risk (RR): 1.01 (95% confidence interval (CI): 0.99–1.04), adjusted relative risk (ARR): 1.02 (95% CI: 0.99–1.05)). However, in fully adjusted models, people with more comorbidities were less likely to have a late-stage diagnosis (adjusted relative risk (ARR): 0.82 (95% CI: 0.80–0.84) for those with 10+ vs. 0–5 ADGs). Compared to adenocarcinoma, small cell carcinoma was more likely to be diagnosed at a late stage (ARR: 1.29; 95% CI: 1.27–1.31), and squamous cell (ARR: 0.89; 95% CI: 0.87–0.91) and other lung cancers (ARR: 0.93; 95% CI: 0.91–0.94) were more likely to be diagnosed at an early stage. Men were also slightly more likely to have late-stage diagnosis in the fully adjusted model (ARR: 1.08; 95% CI: 1.05–1.08). Lung cancer in Ontario is a high-fatality cancer that is frequently diagnosed at a late stage. Having fewer comorbidities and being diagnosed with small cell carcinoma was associated with a late-stage diagnosis. The former group may have less health system contact, and the latter group has the lung cancer type most closely associated with smoking. As lung cancer screening programs start to be implemented across Canada, targeted outreach to men and to smokers, increasing awareness about screening, and connecting every Canadian with primary care should be system priorities.     

Sex differences in survival in non-small cell lung cancer patients 1974-1998

This study comprised a total of 7,553 patients with non-small cell lung cancer (2,660 women and 4,893 men) treated at a comprehensive cancer centre between 1974 and 1998. Significant differences in tumour histology were associated with gender (p < 0.001); adenocarcinoma was the most common diagnosis in both men (50.0%) and women (41.7%); squamous cell carcinoma was the second most prevalent diagnosis (21% and 31% in women and men, respectively); and bronchioalveolar tumours were more prevalent in men (3% compared with 7% in women). Frequency distributions with local, regional or distant disease at registration were similar between men and women (p = 0.906). In a multivariable Cox regression analysis the indications were that gender is an important risk factor for survival. Adjusting for age, stage, treatment received and ability to pay for care, a statistically significant interaction between gender and tumour histology (p = 0.043) was found, where, in relation to female sex and histologies other than squamous carcinoma, women who presented with squamous carcinoma had an increased risk of death (HR = 1.09, 95% CI 1.02-1.18) while men had an increased risk of death for all histologies (HR = 1.29, 95% CI 1.21-1.40, and HR = 1.15, 95% CI 1.07-1.24 for squamous and other histologies, respectively). This study confirms previous reports of strong gender-dependent differences in survival in patients with non-small cell lung cancer, including a histology-specific effect in women.