Cigarette smoking and the risk of thyroid cancer

SYNCHRONOUS DIAGNOSIS OF TESTICULAR AND THYROID CANCER IN A YOUNG MALE

Testicular cancer is the most common neoplasm in young males. The early diagnosis and the appropriate treatment make it a curable malignancy in over 90% of the patients, but 6% of the patients with testicular cancer develop a second, mostly treatment-related, malignancy in another primary site many years after the first diagnosis. The simultaneous appearance of a testicular tumor with another primary neoplasm is rarely described in the literature. Here is presented an interesting case of a coexisting non-seminomatous germ cell testicular tumor with a papillary thyroid carcinoma, which was detected early during post-treatment restaging of the testicular tumor. The synchronous presence of these two neoplasms might indicate a probable common pathogenetic background. As treatment-related oncogenesis is highly improbable in this case and the common environmental factors are not known yet, the interest is focused on genetic predisposition. Recent discoveries in molecular genetics show that the two neoplasms share common genetic alterations in the RAS and BRAF genes, which affect the significant signaling pathways. Interestingly, BRAF-V600E was positive in both primary malignancies in our individual.

Effect of Cigarette Smoking on Thyroid Cancer: Meta-Analysis

BACKGROUND

Although smoking is generally carcinogenic, its effect on thyroid cancers is still subject to controversy. The purpose of this study was to summarize the role of smoking in relation to thyroid cancer occurrence.

METHODS

We performed a meta-analysis of 24 eligible studies: 21 case-control studies and three prospective cohort studies. The summary odds ratio (OR) and 95% confidence interval (CI) of all studies were acquired based on random effect model. Further subgroup analyses were conducted according to gender, histological type of thyroid cancer, and smoking status of patients for the case-control studies.

RESULTS

The summary effect size indicated a negative association of smoking for thyroid cancer (OR, 0.798; 95% CI, 0.681 to 0.935). From the subgroup analyses for the case-control studies, reduced risk of thyroid cancer was observed in both men (OR, 0.734; 95% CI, 0.553 to 0.974) and women (OR, 0.792; 95% CI, 0.700 to 0.897). The protective effect of smoking was observed in studies in which thyroid cancer was limited to differentiated thyroid cancers (DTCs) (OR, 0.798; 95% CI, 0.706 to 0.902).

CONCLUSION

Our results suggests that smoking may have a protective effect on thyroid cancer, especially on DTCs. Further studies with larger sample sizes should be conducted in elucidating the dose and time dependent effect of smoking on thyroid cancer with specific focus on the types of thyroid cancers.

Trends in Childhood Thyroid Cancer incidence in Korea and Its Potential Risk Factors

BACKGROUND

Although the incidence of thyroid cancer had been increasing until a few years ago, a decrease has been observed in the last years, probably due to the reduction of the screening tests in Korea. Childhood thyroid cancer has been increasing in the past with the same trend as in adults, but there have been few reports on recent trends. We analyzed the trends of thyroid cancer in Korean children and related factors.

METHODS

From national statistics and cancer register database, the data of age-specific incidence rate in Korean childhood thyroid cancer from 1999 to 2017 was obtained, and levels of seaweed intake, the number of computed tomography (CT) and neck ultrasonography (US), obesity prevalence rate, and smoking and alcohol consumption rates in children were analyzed.

RESULTS

The age-specific incidence of thyroid cancer in Korean children has increased in both genders between 1999 and 2017 (2.0 in 1999 vs. 7.2 in 2017, per population of 100,000), especially in the age group of 14-18 years (1.5 in 1999 vs. 5.5 in 2017, per population of 100,000). During the same period, levels of seaweed intake, number of CT scans and neck US, and prevalence of obesity in children increased significantly, while childhood smoking and alcohol consumption rates decreased.

CONCLUSION

Unlike the adult thyroid cancer in Korea, childhood thyroid cancer continues to increase, and the cause might be accompanied by actual increases due to the environmental factors such as excessive iodine intake, exposure to medical radiation, and increased obesity prevalence as well as the screening effect.

Associations of intensity, duration, cumulative dose, and age at start of smoking, with thyroid cancer in Chinese males: A hospital-based case-control study in Zhejiang Province

INTRODUCTION

There has been considerable research on the association between smoking status and thyroid cancer risk in males, yet the findings are inconsistent. In this study, we investigated the associations of intensity, duration, cumulative dose, and age at start of smoking, with thyroid cancer in Chinese males.

METHODS

From a 1:1 matched case–control study conducted between 2015 and 2017 in Zhejiang Province, China, 676 pairs of male subjects were included in the analysis. The associations between smoking characteristics and thyroid cancer were evaluated in logistic regression models by odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Compared with never smokers, the former smokers were 0.096 times (95% CI: 0.012–0.778) less likely to have thyroid cancer. The significant inverse association was not observed in current smokers (OR=0.333; 95% CI: 0.084–1.322). Among both former and current smokers, higher smoking intensity (>10 cigarettes/day), duration (>15 years), and cumulative dose of smoking (>10 packyears) were significantly associated with reduced occurrence of thyroid cancer.

CONCLUSIONS

Our findings indicate that former smoking is inversely associated with thyroid cancer occurrence in Chinese males. The reduction in the occurrence of thyroid cancer was also confirmed for both former and current smokers with higher smoking intensity, duration, and cumulative dose.

Healthcare expenditures among community-dwelling adults with thyroid cancer in the United States: A propensity score matched analysis

Objective

This study assessed the excess healthcare expenditures and factors associated with it among community-dwelling adults with thyroid cancer compared to non-cancer controls in the United States.

Method

A retrospective, cross-sectional, matched case-control study design was used by pooling multiple years of Medical Expenditure Panel Survey (MEPS) data (2002–2012). The eligible study sample comprised of adults (age ≥18 years), who were alive during the calendar year and reported positive healthcare expenditure. The case group consisted of adults with thyroid cancer only while the control group consisted of adults who did not have any form of cancer. Total and subtypes of mean annual healthcare expenditures comprised the main study outcome. We also calculated the total and subtypes of out-of-pocket (OOP) expenditures as well as OOP as a percentage of household income. Ordinary Least Square (OLS) regressions on log-transformed expenditures were conducted to elucidate the influence of different factors on healthcare expenditures among adults with thyroid cancer.

Results

The yearly average total healthcare expenditures among adults with thyroid cancer was significantly higher compared to propensity score matched controls ($9,585 vs. $5,830, p < 0.001). Similar observations were found in terms of inpatient, and outpatient expenditures. Functional status as well as comorbid conditions were significantly associated with excess expenditures. The yearly average total OOP expenditure for adults with thyroid cancer was significantly higher compared to matched controls ($1,425 vs. $974, p < 0.001), with major differences observed in inpatient OOP ($178 vs. $24, p = 0.003), outpatient OOP ($435vs. $256, p < 0.001), and prescription OOP ($554 vs. $423, p < 0.001) expenditures. There was a significant (p < 0.001) difference between the average OOP as a percentage of household income between adults with thyroid cancer (Mean: 7.54%, S.E: 1.52%) and matched controls (Mean: 5.80%, S.E: 0.47%).

Conclusions

Our findings suggest that holistic care approach could be helpful to significantly reduce the economic burden in this population. Viable strategies such as limits on OOP costs are required to minimize this high OOP burden among cancer survivors and their families.

Increased Incidence of Thyroid Cancer among World Trade Center First Responders: A Descriptive Epidemiological Assessment

An increased incidence of thyroid cancer among 9/11 rescue workers has been reported, the etiology of which remains unclear but which may, at least partly, be the result of the increased medical surveillance this group undergoes. This study aimed to investigate thyroid cancer in World Trade Center (WTC) responders by looking at the demographic data and questionnaire responses of thyroid cancer cases from the Mount Sinai WTC Health Program (WTCHP). WTCHP thyroid cancer tumors were of a similar size (p = 0.4), and were diagnosed at a similar age (p = 0.2) compared to a subset of thyroid cancer cases treated at Mount Sinai without WTC exposure. These results do not support the surveillance bias hypothesis, under which smaller tumors are expected to be diagnosed at earlier ages. WTCHP thyroid cancer cases also reported a past history of radiation exposure and a family history of thyroid conditions at lower rates than expected, with higher than expected rates of previous cancer diagnoses, family histories of other cancers, and high Body Mass Indexes (BMIs). Further research is needed to better understand the underlying risk factors that may play a role in the development of thyroid cancer in this group.

Cigarette smoking and thyroid cancer risk: a cohort study

Background

We evaluated the association between smoking status and thyroid cancer risk and whether this association is mediated by body mass index (BMI) and thyroid-stimulating hormone (TSH).

Methods

We performed a cohort study of 96,855 Korean adults who were followed annually or biennially for a median of 5.9 years.

Results

During 511,052.9 person-years of follow-up, 1,250 participants developed thyroid cancer. In men, we observed a dose-dependent inverse association between current smoking, pack-years, and thyroid cancer. After adjustment for confounders, adjusted hazard ratios (95% confidence intervals) for thyroid cancer comparing current and former smokers to never smokers were 0.58 (0.45–0.75) and 0.93 (0.73–1.18), respectively. After further adjustment for BMI and TSH as potential mediators, this association was slightly attenuated, but remained significant. For women, current smokers tended to have a lower risk of thyroid cancer, but this association did not reach statistical significance.

Conclusions

In this cohort study, current smoking was associated with a decreased risk of incident thyroid cancer in men but not in women and this association was observed even after adjusting for TSH and BMI levels as potential mediators. Further mechanistic studies are needed to elucidate the possible effect of smoking on the pathogenesis of thyroid cancer development.

Evidence for an Association between Macular Degeneration and Thyroid Cancer in the Aged Population

Direct evidence of whether thyroid cancer patients have a higher risk of age-related macular degeneration (AMD) has yet to be investigated. Patients older than 50 years-old and newly diagnosed with thyroid cancer between 2000 and 2008 were identified from the national health insurance research database (NHIRD). We applied time-varying Cox proportional hazard models to assess the association between thyroid cancer and AMD. The multivariable models included conventional cardiovascular risk factors, myopia, vitreous floaters, hypothyroidism, hyperthyroidism, and treatment modality of thyroid cancer. The analysis process was stratified by age, gender, and comorbidity. In this study, 5253 patients were included in a thyroid cancer cohort (men 24.5%; median age 59.1 years (53.7–67.4 years), and 21,012 matched controls were included in a non-thyroid cancer cohort. The AMD incidence was 40.7 per 10,000 person/year in the thyroid cancer cohort. The thyroid cancer cohort had a higher risk (adjusted hazard ratio (aHR) = 1.38, 95% confidence interval, CI = 1.09–1.75) of AMD than the non-thyroid cohort. Thyroid cancer patients had a higher risk of AMD, especially the male patients (aHR = 1.92, 95% CI = 1.38–3.14) and the patients with comorbidities (aHR = 1.38, 95% CI = 1.09–1.74). In conclusion, thyroid cancer patients older than 50 years-old have increased risk of AMD.

Cigarette Smoking as a Risk Factor for Cancer of the Thyroid in Women

Aims and background

Thyroid cancer, whose etiology is largely uncertain, has been negatively associated with cigarette smoking in a several studies. We examined the association between cigarette smoking and risk for female thyroid cancer.

Methods

A case-control study including 204 histologically verified female thyroid cancer patients and an equal number of hospital controls individually matched with cases by sex, age (± 2 years), place of residence and time of hospitalization was carried out during the period 1996-2000. In the analysis of data, univariate and multivariate conditional logistic regression methods were applied.

Results

According to univariate analysis, female thyroid cancer was negatively associated with the initiation of smoking at a younger age, before the age of 20 (OR = 0.66, 95% CI = 0.50-0.90). None of the smoking habits remained independently related to female thyroid cancer after adjustment for other factors which were significantly associated with thyroid cancer in the present study.

Conclusions

The results of the study do not suggest a role of cigarette smoking in the development of thyroid cancer in women.

Primordial and Primary Preventions of Thyroid Disease

BACKGROUND

Primordial and primary preventions of thyroid diseases are concerned with avoiding the appearance of risk factors, delaying the progression to overt disease, and minimizing the impact of illness.

SUMMARY

Using related key words, 446 articles related to primordial and primary, preventions of thyroid diseases published between 2001-2015 were evaluated, categorized and analyzed. Prevention and elimination of iodine deficiency are major steps that have been successfully achieved and maintained in many countries of the world in last 2 decades. Recent investigations related to the effect of cigarette smoking, alcohol consumption, and autoimmunity in the prevention of thyroid disorders have been reviewed.

CONCLUSIONS

The cornerstone for successful prevention of thyroid disease entails timely implementation of its primordial and primary preventions, which must be highly prioritized in related health strategies by health authorities.

Joint associations of smoking and television viewing time on cancer and cardiovascular disease mortality

Excessive sitting time and smoking are pro-inflammatory lifestyle factors that are associated with both cancer and cardiovascular disease (CVD) mortality. However, their joint associations have not been investigated. We examined the associations of television (TV) viewing time with cancer and CVD mortality, according to smoking status, among 7,498 non-smokers (34% ex-smokers) and 1,409 current-smokers in the Australian Diabetes, Obesity and Lifestyle Study. During 117,506 person-years (median 13.6 years) of follow-up, there were 346 cancer and 209 CVD-related deaths. Including an interaction between TV time and smoking status in the model significantly improved the goodness of fit for cancer (p = 0.01) but not CVD mortality (p = 0.053). In the multivariate-adjusted model, every additional hr/d of TV time was associated with increased risk of cancer-related (HR 1.23; 95% CI 1.08-1.40), but not CVD-related mortality (HR 1.16; 95% CI 0.97-1.38) in current-smokers. Elevated multivariate-adjusted cancer mortality HRs were observed for current-smokers watching 2 to <4 hr/d (HR 1.45; 95% CI 0.78-2.71) and ≥4 hr/d (HR 2.26; 95% CI 1.10-4.64), compared to those watching <2 hr/d. Current-smokers watching 2 to <4 hr/d (HR 1.07; 95% CI 0.45-2.53) and ≥4 hr/d (HR 1.92; 95% CI 0.76-4.84) did not have a significantly higher risk of CVD mortality, compared to <2 hr/d. No associations were observed for non-smokers. These findings show an association of TV, a common sedentary behavior, with cancer mortality in current-smokers. The association with CVD mortality was less clear. Further exploration in larger data sets is warranted. Limiting TV viewing time may be of benefit in reducing cancer mortality risk in current-smokers.

Risk Factors for Thyroid Cancer: A Hospital-Based Case-Control Study in Korean Adults

PURPOSE

Although the incidence of thyroid cancer in Korea has rapidly increased over the past decade, few studies have investigated its risk factors. This study examined the risk factors for thyroid cancer in Korean adults.

MATERIALS AND METHODS

The study design was a hospital-based case-control study. Between August 2002 and December 2011, a total of 802 thyroid cancer cases out of 34,211 patients screened from the Cancer Screenee. Cohort of the National Cancer Center in South Korea were included in the analysis. A total of 802 control cases were selected from the same cohort, and matched individually (1:1) by age (±2 years) and area of residence for control group 1 and additionally by sex for control group 2.

RESULTS

Multivariate conditional logistic regression analysis using the control group 1 showed that females and those with a family history of thyroid cancer had an increased risk of thyroid cancer, whereas ever-smokers and those with a higher monthly household income had a decreased risk of thyroid cancer. On the other hand, the analysis using control group 2 showed that a family history of cancer and alcohol consumption were associated with a decreased risk of thyroid cancer, whereas higher body mass index (BMI) and family history of thyroid cancer were associated with an increased risk of thyroid cancer.

CONCLUSION

These findings suggest that females, those with a family history of thyroid cancer, those with a higher BMI, non-smokers, non-drinkers, and those with a lower monthly household income have an increased risk of developing thyroid cancer.

Risk Factors Associated with Disease Recurrence among Patients with Low-Risk Papillary Thyroid Cancer Treated at the University of the Philippines-Philippine General Hospital

BACKGROUND

The management of papillary thyroid carcinoma (PTC) in high-risk patients is well-standardized. However, this is not the case for low-risk patients. Filipinos show a high incidence of recurrence of thyroid cancer. Thus, the identification of risk factors for recurrence in this population could potentially identify individuals for whom radioactive iodine (RAI) therapy might be beneficial.

METHODS

We reviewed the medical records of adult Filipinos with low-risk PTC who underwent near-total or total thyroidectomy at the University of the Philippines-Philippine General Hospital. Multivariate logistic regression analysis was used to determine risk factors for recurrence.

RESULTS

Recurrence was documented in 51/145 of patients (35.17%) included in this study. Possible risk factors such as age, sex, family history, smoking history, tumor size, multifocality, prophylactic lymph node dissection, initial thyroglobulin (Tg) level, initial anti-thyroglobulin (anti-Tg) antibody concentration, suppression of thyroid stimulating hormone production, and RAI therapy were analyzed. Multivariate analysis revealed that a tumor diameter 2 to 4 cm (odds ratio [OR], 9.17; 95% confidence interval [CI], 1.62 to 51.88; P=0.012), a tumor diameter >4 cm (OR, 16.46; 95% CI, 1.14 to 237.31; P=0.04), and a family history of PTC (OR, 67.27; 95% CI, 2.03 to 2228.96; P=0.018) were significant predictors of recurrence. In addition, RAI therapy (OR, 0.026; 95% CI, 0.01 to 0.023; P≤0.005), an initial Tg level ≤2 ng/mL (OR, 0.049; 95% CI, 0.01 to 0.23; P≤0.005), and an anti-Tg antibody level ≤50 U/mL (OR, 0.087; 95% CI, 0.011 to 0.67; P=0.019) were significant protective factors.

CONCLUSION

A tumor diameter ≥2 cm and a family history of PTC are significant predictors of recurrence. RAI therapy and low initial titers of Tg and anti-Tg antibody are significant protective factors against disease recurrence among low-risk PTC patients.

Fetal growth and subsequent maternal risk of thyroid cancer

Thyroid cancer has peak incidence among women of reproductive age, and growth factors, which have procarcinogenic properties, may play an important etiologic role. However, the association between fetal growth rate during a woman's pregnancy and her subsequent risk of thyroid cancer has not been previously examined. We conducted a national cohort study of 1,837,634 mothers who had a total of 3,588,497 live-births in Sweden in 1973-2008, followed up for thyroid cancer incidence through 2009. There were 2,202 mothers subsequently diagnosed with thyroid cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, height, weight, smoking, and sociodemographic factors, high fetal growth (birth weight standardized for gestational age and sex) was associated with a subsequent increased risk of thyroid cancer in the mother (incidence rate ratio [IRR] per additional 1 standard deviation, 1.05; 95% CI, 1.01-1.09; p = 0.02). Each 1,000 g increase in the infant's birth weight was associated with a 13% increase in the mother's subsequent risk of thyroid cancer (IRR, 1.13; 95% CI, 1.05-1.22; p = 0.001). These findings appeared to involve both papillary and follicular subtypes, and did not vary significantly by the mother's height, weight or smoking status. In this large national cohort study, high fetal growth during a woman's pregnancy was independently associated with a subsequent increased risk of her developing thyroid cancer. If confirmed, these findings suggest an important role of maternal growth factors in the development of thyroid cancer, and potentially may help facilitate the identification of high-risk subgroups of women.

Protocol of a thyroid cancer longitudinal study (T-CALOS): a prospective, clinical and epidemiological study in Korea

INTRODUCTION

Thyroid cancer incidence in Korea is the highest in the world and has recently increased steeply. However, factors contributing to this sudden increase have not been fully elucidated, and few studies have explored the postoperative prognosis. The Thyroid Cancer Longitudinal Study (T-CALOS) was initiated with three aims: (1) to identify factors predicting quality of life, recurrence, and incidence of other diseases after thyroid cancer treatments; (2) to investigate environmental exposure to radiation, toxicants and molecular factors in relation to tumour aggressiveness; and (3) to evaluate gene-environment interactions that increase thyroid cancer in comparison with healthy participants from a pool of nationwide population-based healthy examinees.

METHODS AND ANALYSIS

T-CALOS enrols patients with incident thyroid cancer from three general hospitals, Seoul National University Hospital, Seoul National University Bundang Hospital and National Medical Center, Korea. The study is an ongoing project expecting to investigate 5000 patients with thyroid cancer up until 2017. Healthy examinees with a normal thyroid confirmed by sonography have been enrolled at the Healthy Examination Center at Seoul National University Hospital. We are also performing individual matching using two nationwide databases that are open to the public. Follow-up information is obtained at patients' clinical visits and by linkage to the national database. For statistical analysis, we will use conditional logistic regression models and a Cox proportional hazard regression model. A number of stratifications and sensitivity analyses will be performed to confirm the results.

ETHICS AND DISSEMINATION

Based on a large sample size, a prospective study design, comprehensive data collection and biobank, T-CALOS has been independently peer-reviewed and approved by the three hospitals and two funding sources (National Research Foundation of Korea and Korean Foundation for Cancer Research). The results of T-CALOS will be published according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) criteria.

Modifiable risk factors and thyroid cancer

OBJECTIVE

To evaluate the association between modifiable patient risk factors including tobacco use, alcohol consumption, body mass index (BMI), and thyroid cancer.

STUDY DESIGN

Retrospective study with chart review.

SETTING

Midwest university hospital.

SUBJECTS AND METHODS

Retrospective study comparing Midwest patients with thyroid cancer from our Thyroid Tumor and Cancer Registry with Midwest controls without a personal history of cancer. Descriptive statistics were created from patient questionnaires and chart reviews. Odds ratios (ORs) were reported for significant associations.

RESULTS

There were 467 patients with cancer and 255 controls. The thyroid cancer group included 404 papillary, 47 follicular, 13 medullary, and 3 anaplastic cancers. When comparing all patients with cancer with controls, smoking more than 100 lifetime cigarettes was associated with a reduced cancer risk (OR, 0.68; 95% confidence interval [CI], 0.50-0.94). Secondhand smoke exposure did not show a statistically significant relationship to thyroid cancer. Compared with never drinking, current drinking was associated with a reduced cancer risk (OR, 0.46; 95% CI, 0.29-0.73) as was consuming 1 to 2 drinks daily compared to drinking <1 drink daily (OR, 0.58; 95% CI, 0.34-0.89). There was no difference between median BMI at age 20 years, lifetime maximum BMI, or current BMI between patients with cancer and controls.

CONCLUSION

Our data showed no positive correlation between tobacco use, alcohol consumption, or obesity and thyroid cancer risk. Our data suggest that tobacco use and mild alcohol consumption may be associated with a slightly reduced risk of thyroid cancer. There was no association between BMI and thyroid cancer in our study population.

The influence of the environment on the development of thyroid tumors: a new appraisal

Most epidemiological studies concerning differentiated thyroid cancers (DTC) indicate an increasing incidence over the last two decades. This increase might be partially explained by the better access to health services worldwide, but clinicopathological analyses do not fully support this hypothesis, indicating that there are carcinogenetic factors behind this noticeable increasing incidence. Although we have undoubtedly understood the biology and molecular pathways underlying thyroid carcinogenesis in a better way, we have made very little progresses in identifying a risk profile for DTC, and our knowledge of risk factors is very similar to what we knew 30-40 years ago. In addition to ionizing radiation exposure, the most documented and established risk factor for DTC, we also investigated the role of other factors, including eating habits, tobacco smoking, living in a volcanic area, xenobiotics, and viruses, which could be involved in thyroid carcinogenesis, thus, contributing to the increase in DTC incidence rates observed.

Thyroid cancer risk and smoking status: a meta-analysis

PURPOSE

Previous researchers have reported an inverse association between cigarette smoking and thyroid cancer risk. To summarize the role of smoking in relation to thyroid cancer occurrence, we conducted a meta-analysis.

METHODS

We performed a meta-analysis of 31 eligible studies to summarize the data describing the association between thyroid cancer occurrence and smoking. The case-control studies consisted of 6,260 thyroid cancer cases and 32,935 controls. Cohort studies contained 2,715 thyroid cancer patients that participated from recruitment to follow-up. Q-statistic and I (2) statistic were calculated to examine heterogeneity. Summary relative risks (RRs) and 95 % confidence intervals (95 % CIs) were calculated using a random effects model. Potential sources of heterogeneity were investigated via subgroup and sensitivity analyses, and publication biases were estimated.

RESULTS

Thyroid cancer risk was reduced in persons who had ever-smoked (RR = 0.79; 95 % CI 0.70-0.88) compared with never-smokers. However, strong evidence of heterogeneity was found among the investigated studies; therefore, subgroup analyses were conducted according to study type, smoking status, study location, source of controls, sex, and histological type of thyroid cancer. When the data were stratified by smoking status, an inverse association was observed only among current smokers (RR = 0.74; 95 % CI 0.64-0.86), not former smokers (RR = 1.01; 95 % CI 0.92-1.10). An inverse association was observed only in case-control studies (RR = 0.75; 95 % CI 0.66-0.85).

CONCLUSIONS

This meta-analysis of geographically diverse epidemiological data suggests that smoking, particularly current smoking, may influence susceptibility to thyroid cancer. Further well-designed studies with larger sample sizes should be conducted.

Increase in the incidence of differentiated thyroid carcinoma in children, adolescents, and young adults: a population-based study

OBJECTIVE

To investigate trends in incidence of differentiated thyroid carcinomas among children and adolescents and young adults.

STUDY DESIGN

In this ecological time-trends study, we selected cases of differentiated thyroid carcinomas (1984-2010) in patients <30 years from Surveillance, Epidemiology, and End Results 9 cancer registries by using International Classification of Diseases for Oncology, 3rd edition, codes for papillary and follicular cancers. Patients with multiple other primary diseases before differentiated thyroid carcinomas were excluded. SEER*Stat software, version 8.0.4 (National Cancer Institute, Bethesda, Maryland) was used to calculate age-standardized rates (estimated per 1,000,000/persons) and annual percentage changes (APCs) were calculated by the Joinpoint model (Joinpoint software, version 4.0.4; National Cancer Institute).

RESULTS

Rates ranged from 2.77 (1990) to 9.63 (2009) and from 18.35 (1987) to 50.99 (2009), for male and female subjects, respectively. A significant increasing trend in incidence was observed for both male (APC 3.44; 95% CI 2.60-4.28) and female (APC 3.81; 95% CI 3.38-4.24) patients. When a stratified analysis on the basis of tumor size was performed, significant increasing trends were noted for the following categories: <0.5 cm (females: APC 5.09, 95% CI 3.54-6.65), 0.5-0.9 cm (females: APC 8.45, 95% CI 7.09-9.82), 1.0-1.9 cm (males: APC 5.09, 95% CI 3.20-7.01; females: APC 3.42, 95% CI 2.78-4.07), and ≥2 cm (males: APC 2.62, 95% CI 1.64-3.60; females: APC 2.96, 95% CI 2.34-3.59).

CONCLUSIONS

Incidence rates for differentiated thyroid carcinomas are increasing among children and adolescents and young adults in the US. The increasing trends for larger tumors rules out diagnostic scrutiny as the only explanation for the observed results. Environmental, dietary, and genetic influences should be investigated.

Smoking, alcohol and thyroid cancer occurrence: systematic review and meta-analysis of case-control studies

English language case-control studies reporting on the association of thyroid cancer occurrence with smoking and alcohol drinking are summarized. Two independent researchers performed study selection and data extraction. Random effects model was applied and external adjustment was performed to control for important confounders. Twenty reports published between 1987 and 2007 were included in quantitative synthesis. For smoking, mean association was inverse (odds ratio [OR]: 0.785; 95% CI: 0.701-0.879) remaining after adjustment for alcohol drinking; heterogeneity was moderate. For alcohol drinking, mean association was inverse (OR: 0.795; 95% CI: 0.660-0.958) (remaining after adjustment for smoking, OR: 0.832; 95% CI: 0.688-1.007); heterogeneity was large becoming moderate after adjustment. Data from case-control studies identified showed inverse mean association between thyroid cancer occurrence and ever-smoking or ever-drinking alcohol.

Significance of MDM2 and P14 ARF polymorphisms in susceptibility to differentiated thyroid carcinoma

BACKGROUND

Murine double minute 2 (MDM2) oncoprotein and p14(ARF) tumor suppressor play pivotal roles in regulating p53 and function in the MAPK pathway, which is mutated frequently in differentiated thyroid carcinoma (DTC). We hypothesized that functional polymorphisms in the promoters of MDM2 and p14(ARF) contribute to the interindividual difference in predisposition to DTC.

METHODS

MDM2-rs2279744, MDM2-rs937283, p14(ARF)-rs3731217, and p14(ARF)-rs3088440 were genotyped in 303 patients with DTC and 511 cancer-free healthy controls. Multivariate logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

MDM2-rs2279744 and p14(ARF)-rs3731217 were associated with a significantly increased risk of DTC (MDM2-rs2279744: TT versus TG/GG; OR, 1.5; 95% CI, 1.1-2.0; p14(ARF)-rs3731217: TG/GG versus TT; OR, 1.7; 95% CI, 1.2-2.3). No association was found for MDM2-rs937283 or p14(ARF)-rs3088440. Individuals carrying 3-4 risk genotypes of MDM2 and p14(ARF) had 2.2 times (95% CI, 1.4-3.5) the risk for DTC of individuals carrying 0-1 risk genotypes (P trend = .021). The combined effect of MDM2 and p14(ARF) on risk of DTC was confined to young subjects (≤ 45 years), nonsmokers, nondrinkers, and subjects with a first-degree family history of cancer. These associations were quite similar in strength when cases were restricted to those with papillary thyroid cancer.

CONCLUSION

Our results suggest that polymorphisms of MDM2 and p14(ARF) contribute to the interindividual difference in susceptibility to DTC, either alone or more likely jointly. The observed associations warrant further confirmation in independent studies.

Cigarette smoking, alcohol intake, and thyroid cancer risk: a pooled analysis of five prospective studies in the United States

OBJECTIVE

We examined the associations between cigarette smoking, alcohol intake, and thyroid cancer risk in a pooled analysis of five prospective studies.

METHODS

Data from five prospective U.S. studies were standardized and then combined into one aggregate dataset (384,433 men and 361,664 women). Pooled hazard ratios (HR) and 95 % confidence intervals (CI) for thyroid cancer were estimated from mutually adjusted models of cigarette smoking and alcohol intake, which were additionally adjusted for age, sex, education, race, marital status, body mass index, and cohort.

RESULTS

Over follow-up, 1,003 incident thyroid cancer cases (335 men and 668 women) were identified. Compared to never smokers, current smoking was associated with reduced risk of thyroid cancer (HR = 0.68, 95 % CI 0.55-0.85); this association was slightly stronger among non-drinkers (HR = 0.46, 95 % CI 0.29-0.74). No reduction in risk was observed for former, compared to never, smokers. Greater smoking intensity, duration, and pack-years were associated with further reductions in risk among former and current smokers. Alcohol intake was also inversely associated with thyroid cancer risk (≥7 drinks/week versus 0, HR = 0.72, 95 % CI 0.58-0.90, p trend = 0.002). Inverse associations with smoking and alcohol were more pronounced for papillary versus follicular tumors.

CONCLUSION

The results of this pooled analysis suggest that both cigarette smoking and alcohol consumption are associated with reduced risks of papillary thyroid cancer and, possibly, follicular thyroid cancer.

Smoking and alcohol consumption in relation to risk of thyroid cancer in postmenopausal women

BACKGROUND

Few cohort studies have examined smoking and alcohol consumption in relation to risk of thyroid cancer, and their findings are conflicting.

METHODS

We therefore assessed the association of smoking and alcohol intake with risk of thyroid cancer in a cohort of 159,340 women enrolled in the Women's Health Initiative. Over 12.7 years of follow-up 331 cases of thyroid cancer, of which 276 were papillary thyroid cancer, were identified. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

Compared to never smokers, ever smokers did not have altered risk. Current smokers had reduced risk for all thyroid cancer (HR 0.54, 95% CI 0.29-1.00) and for papillary thyroid cancer (HR 0.34, 95% CI 0.15-0.78); however, the number of current smokers among cases was small. No associations or trends were seen for amount smoked, age of starting smoking, or age at quitting. Smokers of ≥40 pack-years had a significantly reduced risk of papillary thyroid cancer (HR 0.44, 95% CI 0.21-0.89). In contrast, women who had smoked for < 20 years had increased risk of thyroid cancer (HR 1.35, 95% CI 1.05-1.74) and papillary cancer (HR 1.43, 95% CI 1.09-1.89). Alcohol intake was not associated with risk.

CONCLUSION

Our findings suggest that current smoking and having higher pack-years of exposure are associated with a modestly reduced risk of thyroid cancer, whereas alcohol consumption does not appear to affect risk.

Association of Cigarette Smoking with Aberrant Methylation of the Tumor Suppressor Gene RARβ2 in Papillary Thyroid Cancer

Aberrant gene methylation is often seen in thyroid cancer, a common endocrine malignancy. Tobacco smoking has been shown to be associated with aberrant gene methylation in several cancers, but its relationship with gene methylation in thyroid cancer has not been examined. In the present study, we investigated the relationship between smoking of patients and aberrant methylation of tumor suppressor genes for TIMP3, SLC5A8, death-associated protein kinase, and retinoic acid receptor β2 (RARβ2) in papillary thyroid cancer (PTC), the most common type of thyroid cancer. The promoter methylation status of these genes was analyzed using quantitative real-time methylation-specific PCR on bisulfite-treated genomic DNA isolated from tumor tissues and correlated with smoking history of the patients. Among the four genes, methylation of the RARβ2 gene was significantly associated with smoking and other three genes showed a trend of association. Specifically, among the 138 patients investigated, 13/42 (31.0%) ever smokers vs. 10/96 (10.4%) never smokers harbored methylation of the RARβ2 gene (P = 0.003). This association was highly significant also in the subset of conventional variant PTC (P = 0.005) and marginally significant in follicular variant PTC (P = 0.06). The results demonstrate that smoking-associated aberrant methylation of the RARβ2 gene is a specific molecular event that may represent an important mechanism in thyroid tumorigenesis in smokers.

Alcohol drinking, tobacco smoking, and anthropometric characteristics as risk factors for thyroid cancer: a countrywide case-control study in New Caledonia

Exceptionally high incidence rates of thyroid cancer are observed in New Caledonia, particularly in Melanesian women. To investigate further the etiology of thyroid cancer and to clarify the reasons of this elevated incidence, the authors conducted a countrywide population-based case-control study in this multiethnic population. The study included 332 cases with histologically verified papillary or follicular carcinoma (293 women and 39 men) diagnosed in 1993-1999 and 412 population controls (354 women and 58 men) frequency matched by gender and 5-year age group. Thyroid cancer was negatively associated with tobacco smoking and alcohol drinking, but no inverse dose-response relation was observed. Height was positively associated with thyroid cancer, particularly in men. Strong positive associations with weight and body mass index were observed in Melanesian women aged 50 years or more, with an odds ratio of 5.5 (95% confidence interval: 1.5, 20.3) for a body mass index of 35 kg/m2 or greater compared with normal-weight women, and there was a clear dose-response trend. This study clarifies the role of overweight for thyroid cancer in postmenopausal women. Because of the high prevalence of obesity among Melanesian women of New Caledonia, this finding may explain in part the exceptionally elevated incidence of thyroid cancer in this group.

PADB: published association database

Background

Although molecular pathway information and the International HapMap Project data can help biomedical researchers to investigate the aetiology of complex diseases more effectively, such information is missing or insufficient in current genetic association databases. In addition, only a few of the environmental risk factors are included as gene-environment interactions, and the risk measures of associations are not indexed in any association databases.

Description

We have developed a published association database (PADB; ) that includes both the genetic associations and the environmental risk factors available in PubMed database. Each genetic risk factor is linked to a molecular pathway database and the HapMap database through human gene symbols identified in the abstracts. And the risk measures such as odds ratios or hazard ratios are extracted automatically from the abstracts when available. Thus, users can review the association data sorted by the risk measures, and genetic associations can be grouped by human genes or molecular pathways. The search results can also be saved to tab-delimited text files for further sorting or analysis. Currently, PADB indexes more than 1,500,000 PubMed abstracts that include 3442 human genes, 461 molecular pathways and about 190,000 risk measures ranging from 0.00001 to 4878.9.

Conclusion

PADB is a unique online database of published associations that will serve as a novel and powerful resource for reviewing and interpreting huge association data of complex human diseases.

A case-control study in Hiroshima and Nagasaki examining non-radiation risk factors for thyroid cancer

BACKGROUND

Because little is known about the etiology of thyroid cancer in Japan, we conducted a case-control study of thyroid cancer and lifestyle and other risk factors. The present report focuses on medical history, family history, smoking and alcohol drinking, and their interactions with radiation exposure.

METHODS

Thyroid cancer cases reported to the Hiroshima and Nagasaki tumor registries during 1970-1986 were histologically reviewed by pathologists. For each of 362 cases with papillary or follicular adenocarcinoma diagnosed at <75 years of age, one control without cancer matched on city, sex, year of birth, and atomic-bomb radiation exposure was selected from the Life Span Study cohort or the offspring cohort. The cohort subjects were residents of Hiroshima and Nagasaki with or without atomic-bomb radiation exposure. Information on risk factors was obtained through a pre-structured interview carried out in 1986-1988.

RESULTS

Analysis using conditional logistic regression showed history of goiter or thyroid nodule and family history of cancer to be significantly associated with an increased odds ratio for thyroid cancer. Smoking and alcohol drinking were significantly and independently associated with a reduced odds ratio. Interaction between smoking and alcohol drinking was not evident based on either an additive model or a multiplicative model. Radiation exposure did not significantly modify the associations between these factors and thyroid cancer risk.

CONCLUSION

History of goiter/nodule and family history of cancer were risk factors for thyroid cancer. Smoking and alcohol drinking were independently associated with reduced risk. Self-reported retrospective information presents some limitations in interpretation of the data.

Thyroid cancer and employment as a radiologic technologist

The association between chronic occupational ionizing radiation exposure in the medical field and thyroid cancer is not well characterized. Thyroid cancer incidence was ascertained for 2 periods in a cohort of radiologic technologists certified for a minimum 2 years and enumerated in 1983: (i) cases identified prospectively in 73,080 radiologic technologists who were free of thyroid cancer at the baseline survey and completed a second questionnaire a decade later (N = 121), and (ii) cases occurring prior to cohort enumeration among 90,245 technologists who completed the baseline survey and were thyroid cancer free 2 years after certification (N = 148). Survival analyses estimated risks associated with employment as a radiologic technologist, including duration of employment, period of employment, types of procedures and work practices. The only occupational history characteristic associated with prospectively identified thyroid cancer was a history of holding patients for X-ray procedures at least 50 times (HR = 1.47, 95% CI = 1.01-2.15). Total years worked as a radiologic technologist, years performing diagnostic, therapeutic, and nuclear medicine procedures, employment under age 20 and calendar period of first employment were not associated with thyroid cancer risk. Risk of thyroid cancers diagnosed before the baseline questionnaire was inversely associated with decade first employed as a technologist, and was elevated, albeit imprecisely, among those working more than 5 years prior to 1950 (HR = 3.04, 95% CI = 1.01-10.78). These data provide modest evidence of an association between employment as a radiologic technologist and thyroid cancer risk; however, the findings require confirmation with more accurate exposure models.

Risk of second primary malignancies in women with papillary thyroid cancer

Second malignancies in women diagnosed with thyroid cancer are of concern given the young average age at diagnosis and excellent survival. Data from the California Cancer Registry were used to evaluate the risk of second primary cancers among a retrospective population-based cohort of 10,932 women diagnosed with papillary thyroid cancer between 1988 and 1999. Follow-up was calculated from 2 months until the diagnosis of a second primary cancer, death, loss to follow-up, or December 31, 1999, whichever occurred first. Standardized incidence ratios, based on age-specific cancer incidence rates for California women, were calculated. During a total of 50,938 person-years of follow-up (mean: 4.7 years), 279 women developed a second primary cancer. The incidence of invasive breast cancer was not elevated compared with California women overall (standardized incidence ratio (SIR) = 0.9, 95% confidence interval (CI): 0.7, 1.1) or when stratified by age, race/ethnicity, follow-up, or radiation treatment. An excess of in situ breast cancer (SIR = 1.6, 95% CI: 1.0, 2.4), kidney cancer (SIR = 3.9, 95% CI: 2.2, 6.3), and melanoma (SIR = 2.1, 95% CI: 1.3, 3.2) limited to the first 5 years after diagnosis was observed. Women with papillary thyroid cancer are at increased risk of in situ, but not invasive, breast cancer, kidney cancer, and melanoma.

Molecular Prognosticators and Genomic Instability in Papillary Thyroid Cancer

OBJECTIVES/HYPOTHESIS

Tumor progression has been attributed to the accumulation of DNA damage concurrent with selection of advantageous mutations; this DNA damage may result from failure to maintain genomic integrity or from susceptibility to carcinogens. Glutathione S-transferases (GSTs), enzymes that metabolize many carcinogens, may play a role in preserving genome integrity. The objectives of this study are to assess the relationship of GST genotypes with prognosis, clinicopathologic parameters, and genomic instability in papillary thyroid cancer.

STUDY DESIGN

Prospective analysis.

METHODS

GSTM1 and GSTT1 genotypes of 35 matched normal and papillary thyroid cancer specimens were determined by polymerase chain reaction (PCR) using primers specific for the coding sequences of each gene. Genomic instability was measured by intersimple sequence repeat PCR for each tumor/normal pair and compared with the GAMES prognostic scoring system and clinicopathologic parameters including age, extrathyroidal extension, tumor grade, size, stage metastasis, sex, and smoking history.

RESULTS

GSTM1 and GSTT1 null genotypes were found in the normal tissues of 46% and 45%, respectively. No gene losses were detected in the tumor specimens. A significant association between the GSTM1 null genotype and increased risk of recurrence and death was observed. Elevated GII correlated with smoking and tumor stage but not with GST genotype.

CONCLUSION

The association of GSTM1 null genotype with intermediate and high risk GAMES categories suggests that GSTM1 provides some protection against disease progression. However, this protection does not confer resistance to disease onset. GST genotyping may be a useful adjunct prognosticator with GAMES.

Overview of smoking and all cancers

Tobacco consumption has been clearly implicated in the causation of many cancer types, with irrefutable evidence to support the association in multiple organ systems. Tobacco cessation leads to reduced cancer risk and improved survival of those under treatment for their already established cancers. As understanding of the mechanisms by which tobacco products cause cancer increases, clinicians may be able to identify those at highest risk for tobacco-related malignancies and allow for more focused interventions toward risk reduction among current tobacco users. This article reviews the carcinogens present in tobacco products, the mechanisms by which tobacco causes cancer, and the various tumor types causally related to tobacco use.

Classification and incidence of cancers in adolescents and young adults in England 1979-1997

Cancer patients aged 15-24 years have distinct special needs. High quality cancer statistics are required for service planning. Data presented by primary site are inappropriate for this age group. We have developed a morphology-based classification and applied it to national cancer registration data for England 1979-1997. The study included 25,000 cancers and 134 million person-years at risk. Rates for each diagnostic group by age, sex and time period (1979-83, 1984-87, 1988-92, 1993-1997) were calculated. Overall rates in 15-19 and 20-24-year-olds were 144 and 226 per million person-years respectively. Lymphomas showed the highest rates in both age groups. Rates for leukaemias and bone tumours were lower in 20-24 year olds. Higher rates for carcinomas, central nervous system tumours, germ-cell tumours, soft tissue sarcomas and melanoma were seen in the older group. Poisson regression showed incidence increased over the study period by an average of 1.5% per annum (P<0.0001). Significant increases were seen in non-Hodgkins lymphoma (2.3%), astrocytoma (2.3%), germ-cell tumours (2.3%), melanoma (5.1%) and carcinoma of the thyroid (3.5%) and ovary (3.0%). Cancers common in the elderly are uncommon in adolescents and young adults. The incidence of certain cancers in the latter is increasing. Future studies should be directed towards aetiology.

Epidemiology and primary prevention of thyroid cancer

The purpose of this review is to provide an account of our present knowledge about the epidemiology of nonmedullary thyroid carcinoma, to discuss the effects of environment, lifestyle and radiation on the risk of developing thyroid cancer, and to discuss aspects on primary prevention of the disease. In areas not associated with nuclear fallout, the annual incidence of thyroid cancer ranges between 2.0-3.8 cases per 100,000 in women and 1.2-2.6 per 100,000 in men, women of childbearing age being at highest risk. Low figures are found in some European countries (Denmark, Holland, Slovakia) and high figures are found in Iceland and Hawaii. Differences in iodine intake may be one factor explaining the geographic variation, high iodine intake being associated with a slightly increased risk of developing thyroid cancer. In general, lifestyle factors have only a small effect on the risk of thyroid cancer, a possible protective effect of tobacco smoking has been recently reported. Because of the (small) increase in risk of thyroid cancer associated with iodination programs, these should be supervised, so that the population does not receive excess iodine. The thyroid gland is highly sensitive to radiation-induced oncogenesis. This is verified by numerous reports from survivors after Hiroshima and Nagasaki, the Nevada, Novaja Semlja and Marshal Island atmospheric tests, and the Chernobyl plant accident, as well as by investigations of earlier medical use of radiation for benign diseases in childhood. These reports are summarized in the review. There appears to be a dose-response relation for the risk of developing cancer after exposure to radioactive radioiodine. The thyroid gland of children is especially vulnerable to the carcinogenic action of ionizing radiation. Thus, the incidence of thyroid cancer in children in the Belarus area was less than 1 case per million per year before the Chernobyl accident, increasing to a peak exceeding 100 per million per year in certain areas after the accident. It is a social obligation of scientists to inform the public and politicians of these risks. All nuclear power plants should have a program in operation for stockpiling potassium iodide for distribution within 1-2 days after an accident.

Thoughts on prevention of thyroid disease in the United States

In the realm of preventive medicine, there are three distinct types of prevention that can be defined. Primary prevention is the prevention of new disease in previously healthy individuals, usually achieved by decreasing risk factors for disease. Secondary prevention is the prevention of progression of mild or latent disease to more severe disease, and typically involves screening for occult disease. Tertiary prevention is the term used by some to describe medical care intended to improve already established disease. The role of primary prevention of thyroid disease in the United States is uncertain, because iodine deficiency is not clearly known to be a problem. In the case of secondary prevention of thyroid disease, this would necessarily involve screening of individuals for subclinical hyperthyroidism or hypothyroidism with thyrotropin (TSH) testing. Using data from a large prevalence study and from the 2000 U.S. Census, it can be calculated that approximately 15 million adults have unrecognized thyroid disease, mostly subclinical hypothyroidism. If detected, secondary prevention might also entail treatment with antithyroid drugs/radioiodine or thyroxine to prevent sequelae or progression to a more advanced degree of thyrotoxicosis or thyroid failure, respectively. Over the next 20 years, it can be calculated that approximately 5 million people, mostly with subclinical hypothyroidism, will progress to overt disease. Tertiary prevention of thyroid disease would involve avoiding iatrogenic disease, such as thyroid hormone overdose. From epidemiologic data it can be calculated that approximately 600,00 elderly individuals have iatrogenic hyperthyroidism from thyroid hormone overdose, putting them at risk for atrial fibrillation and osteoporosis. Together, these data suggest that the notion of preventive medicine in the United States should be expanded to include thyroid disease as a target for secondary and tertiary intervention.

Tobacco use and cancer causation: association by tumour type

In the second part of our review we describe the association between tobacco use and risk of specific cancer types. There is evidence for an established association of tobacco use with cancer of the lung and larynx, head and neck, bladder, oesophagus, pancreas, stomach and kidney. In contrast, endometrial cancer is less common in women who smoke cigarettes. There are some data suggesting that tobacco use increases the risk for myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancer of the gall bladder, adrenal gland and small intestine. Other forms of cancer, including breast, ovarian and prostate cancer, are unlikely to be linked to tobacco use.