Yana Bai

International patterns and trends in thyroid cancer incidence, 1973–2002

During the past several decades, an increasing incidence of thyroid cancer has been reported in many parts of the world. To date, no study has compared the trends in thyroid cancer incidence across continents. We examined incidence data from cancer incidence in five continents (CI5) over the 30-year period 1973–2002 from 19 populations in the Americas, Asia, Europe, and Oceania. Thyroid cancer rates have increased from 1973–1977 to 1998–2002 for most of the populations except Sweden, in which the incidence rates decreased about 18% for both males and females. The average increase was 48.0% among males and 66.7% among females. More recently, the age-adjusted international thyroid cancer incidence rates from 1998 to 2002 varied 5-fold for males and nearly 10-fold for females by geographic region. Considerable variation in thyroid cancer incidence was present for every continent but Africa, in which the incidence rates were generally low. Our analysis of published CI5 data suggests that thyroid cancer rates increased between 1973 and 2002 in most populations worldwide, and that the increase does not appear to be restricted to a particular region of the world or by the underlying rates of thyroid cancer.

A Birth Cohort Analysis of the Incidence of Papillary Thyroid Cancer in the United States, 1973–2004

BACKGROUND The incidence of papillary thyroid cancer has been reported to be increasing during the past three decades, with a 65-126% increase between 1975 and 2004. The reason for the increase is currently unknown. This study examined the incidence pattern of papillary thyroid cancer in the United States, and evaluated the components of birth cohort (defined based on year of birth), time period, and age as determinants of the observed time trend of the disease. METHODS Using the data from the National Cancer Institutes Surveillance, Epidemiology, and End Results program for 1973-2004, we conducted both univariate analysis and age-period-cohort modeling to evaluate birth cohort patterns and evaluate age, period, and cohort effects on incidence trends over time. RESULTS The increasing incidence showed a clear birth cohort pattern for both men and women. The results from age-period-cohort modeling showed that, while period effect appeared to have had an impact on the observed incidence trends, birth cohort effect may also explain part of the increasing trend in papillary thyroid carcinoma during the study period, especially among women. CONCLUSION While a period effect that is likely due to advancements in diagnostic techniques and increased medical detection of small thyroid nodules may explain some of the observed increase in the incidence, we speculate that birth cohort-related changes in environmental exposures (such as increased exposure to diagnostic X-rays and polybrominated diphenyl ethers) have also contributed to the observed increase in papillary thyroid cancer during the past decades.

Vegetable and fruit intake and non-Hodgkin lymphoma survival in Connecticut women

We investigated whether an increased intake of vegetables and fruits favors NHL survival. A cohort of 568 female cases of incident NHL diagnosed during 1996–2000 in Connecticut was followed up for a median of 7.7 years. Adjusted hazard ratios (HRs) were estimated by Cox proportional hazard models. Our results show that a pre-diagnostic high intake of vegetables appeared to favor overall survival (HR = 0.74, 95% CI 0.57–0.98) among patients with NHL who survived longer than 6 months. In particular, pre-diagnostic high intakes of green leafy vegetables and citrus fruits were associated with 29% (95% CI 0.51–0.98) and 27% (95% CI 0.54–0.99) reduced risk of death, respectively. When different types of vegetables and fruits were investigated separately, their impacts were found to vary in NHL subtypes. Our study suggests that increasing vegetable and citrus fruit consumption could be a useful strategy to improve survival in NHL patients.

Sexual functioning among testicular cancer survivors: A case–control study in the U.S.

OBJECTIVE Sexual function among testicular cancer survivors is a concern because affected men are of reproductive age when diagnosed. We conducted a case-control study among United States military men to examine whether testicular cancer survivors experienced impaired sexual function. METHODS A total of 246 testicular cancer cases and 236 ethnicity and age matched controls were enrolled in the study in 2008-2009. The Brief Male Sexual Function Inventory (BMSFI) was used to assess sexual function. RESULTS Compared to controls, cases scored significantly lower on sex drive (5.77 vs. 5.18), erection (9.40 vs. 8.63), ejaculation (10.83 vs. 9.90), and problem assessment (10.55 vs. 9.54). Cases were significantly more likely to have impaired erection (OR 1.72; 95% CI 1.11-2.64), ejaculation (OR 2.27; 95% CI 1.32-3.91), and problem assessment (OR 2.36; 95% CI 1.43-3.90). In histology and treatment analysis, nonseminoma, chemotherapy and radiation treated cases risk of erectile dysfunction, delayed ejaculation, and/or problem assessment were greater when compared to controls. CONCLUSION This study provides evidence that testicular cancer survivors are more likely to have impaired sexual functioning compared to demographically matched controls. The observed impaired sexual functioning appeared to vary by treatment regimen and histologic subtype.

Histone Methylation in Nickel-Smelting Industrial Workers

Background Nickel is an essential trace metal naturally found in the environment. It is also common in occupational settings, where it associates with various levels of both occupational and nonoccupational exposure In vitro studies have shown that nickel exposure can lead to intracellular accumulation of Ni2+, which has been associated with global decreases in DNA methylation, increases in chromatin condensation, reductions in H3K9me2, and elevated levels of H3K4me3. Histone modifications play an important role in modulating chromatin structure and gene expression. For example, tri-methylation of histone H3k4 has been found to be associated with transcriptional activation, and tri-methylation of H3k27 has been found to be associated with transcriptional repression. Aberrant histone modifications have been found to be associated with various human diseases, including cancer. The purpose of this work was to identify biomarkers for populations with occupational nickel exposure and to examine the relationship between histone methylation and nickel exposure. This may provide a scientific indicator of early health impairment and facilitate exploration of the molecular mechanism underlying cancer pathogenesis. Methods One hundred and forty subjects with occupational exposure to Ni and 140 referents were recruited. H3K4 and H3K27 trimethylation levels were measured in subjects’ blood cells. Results H3K4me3 levels were found to be higher in nickel smelting workers (47.24±20.85) than in office workers (22.65±8.81; P = 0.000), while the opposite was found for levels of H3K27me3(nickel smelting workers, 13.88± 4.23; office workers, 20.67± 5.96; P = 0.000). H3K4me3 was positively (r = 0.267, P = 0.001) and H3K27 was negatively (r = -0.684, P = 0.000) associated with age and length of service in smelting workers. Conclusion This study indicated that occupational exposure to Ni is associated with alterations in levels of histone modification.

A Retrospective Cohort Mortality Study in Jinchang, the Largest Nickel Production Enterprise in China

Nickel is an essential trace metal used in the occupational setting, resulting in both occupational and nonoccupational exposures to individuals at varying levels. Exposure to nickel has been associated with several toxicities and the International Agency for Research on Cancer has concluded that there is sufficient evidence in humans associating exposure to nickel compounds with risk of lung cancer and sinonasal cancer. This study confirmed a significant excess of mortality from diseases of the lung including silicosis, lung cancer, and cor pulmonale among workers involved in nickel mining or smelting in China.

Genetic Variations in Xenobiotic Metabolic Pathway Genes, Personal Hair Dye Use, and Risk of Non-Hodgkin Lymphoma

From 1996 to 2000, the authors conducted a population-based case-control study among Connecticut women to test the hypothesis that genetic variation in xenobiotic metabolic pathway genes modifies the relation between hair dye use and risk of non-Hodgkin lymphoma. No effect modifications were found for women who started using hair dyes in 1980 or afterward. For women who started using hair dye before 1980 as compared with never users, a statistically significantly increased risk of non-Hodgkin lymphoma was found for carriers of CYP2C9 Ex3-52C>T TT/CT genotypes (odds ratio (OR) = 2.9, 95% confidence interval (CI): 1.4, 6.1), CYP2E1 -332T>A AT/AA genotypes (OR = 2.0, 95% CI: 1.2, 3.4), a homozygous or heterozygous 3-base-pair deletion in intron 6 of GSTM3 (OR = 2.3, 95% CI: 1.3, 4.1), GSTP1 Ex5-24A>G AA genotypes (OR = 1.8, 95% CI: 1.1, 2.9), or NAT2 genotypes conferring intermediate/rapid acetylator status (OR = 1.6, 95% CI: 1.0, 2.7). The observed associations were mainly seen for follicular lymphoma. In contrast, no significantly increased risk was observed for starting hair dye use before 1980 (relative to never use) among women who were homozygous wild-type for the CYP2C9, CYP2E1, or GSTM3 polymorphisms, women carrying 1 or 2 copies of the variant GSTP1 allele, or women who were slow NAT2 acetylators. A possible role of genetic variation in xenobiotic metabolism in the carcinogenicity of hair dye use needs to be confirmed in larger studies.

Metals compositions of indoor PM2.5, health risk assessment, and birth outcomes in Lanzhou, China.

The study aimed to investigate the metal compositions in indoor PM2.5 and the potential health risks they pose to residents of an urban area in China. A total of 41 and 54 households were surveyed in February and September 2013, respectively. The results showed that the indoor concentrations of metals varied depending on the types of cooking fuels used. All measured concentrations of metals were highest among households using coal for cooking. In the majority of households, non-carcinogenic risks were posed by the use of coal. The carcinogenic risks posed by chromium (VI) and arsenic were generally higher among households using coal for cooking than among those using gas or electricity. The multivariate linear regression model suggested a potential adverse effect from arsenic and cadmium on birth weight and gestational weeks. This study also found that cooking fuel was the most significant factor that contributed to the differences in concentrations of metals in indoor PM2.5 and highlighted the importance of using clean energy for cooking and heating.

Metabolic syndrome and the risk of breast cancer among postmenopausal women in North-West China.

ABSTRACT Objective To determine whether metabolic syndrome (MetS) and its components are risk factors for breast cancer among postmenopausal women in China. Methods Based on the baseline data of the Jinchang Cohort, a case–control study was carried out among postmenopausal women, including 43 cases and 86 controls. Both MetS and its components were evaluated. Odds ratios and 95% confidence intervals (CI) for the association were estimated by conditional logistic regression analysis. Results The odds ratio of postmenopausal breast cancer was 3.505 (95% CI 1.282–9.583) for MetS, 3.016 (95% CI 1.044–8.715) for body mass index (BMI) ≥ 25 kg/m2, and 3.191 (95% CI 1.253–8.125) for dyslipidemia. There was no significant association between postmenopausal breast cancer and hypertension as well as diabetes. Women with four metabolic factors showed greater risk for postmenopausal breast cancer (ptrend < 0.05). Dyslipidemia and BMI ≥ 25 kg/m2 showed most significant interaction on breast cancer (odds ratio = 11.359; 95% CI 2.663–48.450). With BMI ≥ 25 kg/m2, the interaction of dyslipidemia and other metabolic factors on breast cancer was higher than that without BMI ≥ 25 kg/m2. Conclusion This case–control study suggested that MetS was associated with an elevated risk of breast cancer among postmenopausal women in north-west China. Overweight and dyslipidemia had the strongest adverse effects on postmenopausal breast cancer.

Metal Exposure and Risk of Diabetes and Prediabetes among Chinese Occupational Workers.

OBJECTIVE To study the association between metal exposure and risk of diabetes and prediabetes among Chinese workers exposed to metals. METHODS We used data obtained from the baseline survey of the Jinchang Cohort Study of workers in Jinchang Industry, the largest nickel production company in China. A total of 42,122 workers ⋝20 years of age were included in the study. A standardized, structured questionnaire was used to collect epidemiological information. Physical examinations and laboratory tests were conducted to evaluate the health status of the participants and to measure various biomarkers including blood sugar, lipids, and urinary metal concentrations. Logistic regression was used to study the association between occupational groups categorized according to the measured metal levels (office workers, low-level; mining/production workers, mid-level; and smelting/refining workers, high-level) and risk of diabetes and prediabetes. RESULTS The overall prevalence of diabetes and prediabetes was 7.5% and 16.8%, respectively. The adjusted odds ratios for diabetes among mining/production workers and smelting/refining workers compared to office workers were 1.5 (95% CI: 1.3, 1.7) and 3.8 (95% CI: 3.4, 4.3), respectively. No association was observed between these occupational groups and prediabetes in this study. CONCLUSION Occupations associated with higher levels of metal exposure were associated with an increased risk of diabetes in this cohort. More studies are needed to confirm this observed association.