[Analysis of sensitivity and specificity of sputum cytology screening for lung cancer with different positive criteria].

OBJECTIVE: To discuss the effect of different positive criteria on the sensitivity and specificity of sputum cytology screening for lung cancer among Yunnan tin miners. METHODS: 9223 Yunnan tin miners who received at least one annual sputum cytology screening for lung cancer during the period between 1992 and 1999 were recruited in the study. At time of enrollment, all participants were aged over 40 years old, had at least 10 years of employment as an underground miner and(or) smelter, and had not been diagnosed with malignancy. In our study, a true positive was categorized as having at least one prior positive sputum screening and a diagnosis of lung cancer, while a true negative, by our definition, signified negative sputum examinations and no diagnosis of lung cancer during the follow up time. Based on different positive criteria, sensitivity and specificity of sputum cytology were computed and receiver operating characteristic (ROC) curve analysis was conducted. Z statistic was used to test the differences of the area under ROC based on Hanley and McNeil method. RESULTS: By the end of following up on December 31, 2001, a total 500 lung cancer cases were diagnosed among 9223 participants: most were squamous cell carcinoma (55.8% (222/398)) and central lung cancers (68.5% (316/461)). 150 lung cancer cases had a previous positive sputum screening result. When positive criteria were taken as grave atypical metaplasia, moderate atypical metaplasia and slight atypical metaplasia, the corresponding sensitivities were 30.0% (150/500), 36.4% (182/500), 53.0% (265/500) respectively; while the corresponding specificities were 98.9% (8628/8723), 95.1% (8611/8723), 77.9% (7033/8723) respectively. The areas under ROC curve according to different positive criterias were 0.645 (95%CI: 0.635 - 0.654), 0.657 (95%CI: 0.668 - 0.667), 0.655 (95%CI: 0.645 - 0.664) respectively. There were no significant differences found in the comparisons between grave and moderate atypical metaplasia, grave and slight atypical metaplasia, moderate and slight atypical metaplasia(Z statistics were 0.780, 0.645, 0.209 respectively, all P values > 0.05). CONCLUSION: While the standard of positive criteria for diagnosis of lung cancer decreased, the sensitivity of sputum cytology screening increased and the specificity decreased. Since there were no significant differences of accuracy for different positive criteria.

Prior lung disease and lung cancer risk in an occupational-based cohort in Yunnan, China.

We used the data from a prospective cohort study among tin miners in Yunnan, China to investigate whether prior lung disease is a risk factor for lung cancer. Information on prior lung disease was obtained from baseline questionnaires. The Cox proportional hazards model was used to examine the relationship between prior lung disease and lung cancer risk. From 1992 to 2001, a total of 502 lung cancer cases were confirmed among 9295 cohort participants. Prior chronic bronchitis was associated with an increase in lung cancer risk with an adjusted HR of 1.50 (95% CI: 1.24-1.81). There was an increased risk of developing squamous cell carcinoma in the setting of prior chronic bronchitis and small cell carcinoma in association with asthma with an adjusted HRs of 1.57 (95% CI: 1.19-2.09) and 2.56 (95% CI: 1.38-4.75), respectively. This prospective study provides further evidence that prior chronic bronchitis correlates with increased lung cancer risk, especially for squamous cell carcinoma. Asthma is associated with increased risk of small cell lung carcinoma.

Association between sputum atypia and lung cancer risk in an occupational cohort in Yunnan, China.

BACKGROUND: Individuals with cytologic atypia in sputum may be at high risk for the development of lung cancer. METHODS: A prospective cohort study was conducted among occupational tin miners in Yunnan, China, based on an annual lung cancer screening program. Sputum samples were collected prospectively at baseline and the following seven annual screenings. The associations between risk factors and sputum cytology were analyzed by univariate and multivariate logistic regression. A proportional hazard model was used to analyze the association between the baseline sputum results and the incidence of lung cancer. The effect of consecutive sputum cytology on the increase of lung cancer risk was analyzed by logistic regression. RESULTS: Sputum cytologic atypia was associated with age, smoking, occupational radon and arsenic exposure, and asthma. Sputum cytologic atypia was an independent risk factor for lung cancer with an adjusted hazard ratio (HR) of 3.82 (95% confidence interval [CI], 2.82 to 5.18) in comparing normal to moderate or worse atypia. Compared to the lung cancer risk associated with normal sputum, the risk was significantly higher according to the degree of atypia for squamous carcinomas, small cell lung cancer and central lung cancer, with adjusted HRs of 5.70 (95% CI, 3.78 to 8.59), 3.32 (95% CI, 1.31 to 8.45), and 4.93 (95% CI, 3.51 to 6.92), respectively. CONCLUSIONS: Sputum atypia is associated with an increased risk of lung cancer. Sputum cytologic examination combined with other screening examinations may play an important role in the early detection of lung cancer or in the selection of the optimal target population for more intensive lung cancer screening among this occupational cohort or similar population.

[An epidemiological study of the neoplasm mortality in Gejiu residents from 1996 to 2005].

OBJECTIVE: To assessment the trend of the mortality of the neoplasm among the residents in Gejiu city of Yunnan province and to provide scientific evidences for the neoplasm prevention. METHODS: Data of mortality of the neoplasm from 1996 to 2005 was collected and analyzed through a retrospective survey. RESULTS: The mortality was going up in the recent epidemiological surveys. The increase trend was showed on the mortality from 1996 to 2005. The mortality was 53.25 per 100,000 of 1996 increased to 70.58 per 100,000 in 2005. The mortality in female was 23.76 per 100,000 in 1996 increased to 50.57 per 100,000 of 2005. CONCLUSION: The neoplasm is still a leading disease in Gejiu city. The main cancer was lung cancer in the neoplasms. The mortality of the neoplasma in the town residents was higher than the countryside. It is necessary to enhance neoplasm prevention.

Effects of fat-soluble extracts from vegetable powder and beta-carotene on proliferation and apoptosis of lung cancer cell YTMLC-90.

OBJECTIVE: The aim of this investigation was to study the effects of fat-soluble extracts from vegetable powder (FEFVP) and beta-carotene on the proliferation and apoptosis of cultured YTMLC-90 lung cancer cells. METHODS: The lung cancer cells were continuously exposed to a broad range of concentration of FEFVP and beta-carotene. The proliferation was evaluated in MTT test. The induction of apoptosis was evaluated by morphological change, DNA fragmentation analysis, and DNA content analysis combined with flow cytometric analysis. RESULTS: Both FEFVP and beta-carotene were found to inhibit cell proliferation and to induce morphologic changes consistent with apoptosis in YTMLC-90 cancer cells, including cellular shrinkage, chromatin condensation and nuclear fragmentation. DNA agarose gel electrophoresis showed DNA fragmentation 'ladder'. Flow cytometric analysis revealed decreased DNA content and the presence of a sub-G1 apoptotic peak. CONCLUSION: These findings are consistent with the induction of apoptosis. Moreover, the effects of FEFVP are stronger than those of beta-carotene. FEFVP inhibits the growth of YTMLC-90 probably via the induction of apoptosis cancer cells.

Gene-environment interactions between the codon 194 polymorphism of XRCC1 and antioxidants influence lung cancer risk.

X-ray repair cross complementing group 1 (XRCC1) is a DNA repair gene whose polymorphisms appear to influence the risk of lung cancer. We explored the influence of antioxidants on the association between the codon 194 arganine to tryptophan substitution polymorphism of XRCC1 and lung cancer risk. In a case-control study nested within a cohort of tin miners the cases were those diagnosed with lung cancer over 6 years of follow-up (n = 108). Two controls, matched on age and sex, were selected for each case by incidence density sampling. Individuals with the variant Arg194Trp allele seemed to be at lower risk for lung cancer (odds ratio (OR): 0.7, 95% confidence interval (95%CL): 0.4-1.2). Furthermore, high serum alpha-tocopherol (OR: 0.4, 95%CL: 0.2-0.9) and retinol (OR: 0.4, 95%CL: 0.2-0.9) levels were associated with significantly reduced risk of lung cancer among individuals with the Arg194Trp variant allele, but not among individuals with the wild-type genotype. In addition, the Arg194Trp variant reduced the risk of lung cancer associated with increased serum carotenoids compared to those with the homozygous wild-type allele. Our results show that Arg194Trp XRCC1 variant modifies the association between serum antioxidants and lung cancer risk.