Recreational physical activity and risk of papillary thyroid cancer among women in the California Teachers Study

Incidence of thyroid cancer in Puerto Rico and the US by racial/ethnic group, 2011-2015

BACKGROUND

Puerto Rico has the highest incidence rate of thyroid cancer (TC) in the Americas and the third highest rate worldwide. The purpose of this study was to compare the burden of TC between the population of PR and United States (US) non-Hispanic Whites (NHW), non-Hispanic Blacks (NHB), and US Hispanics (USH) during the period 2011-2015.

METHODS

TC data for the period 2011-2015 was obtained from the Puerto Rico Central Cancer Registry (PRCCR) and the Surveillance Epidemiology and Ends Results Program (SEER) 18 Registries Research Data. TC was categorized in: papillary carcinoma (PTC), and other TC histologic types. Data was analyzed by sex, age groups, and histologic type. Racial/ethnic differences by sex, age, and histologic types were assessed using the Standardized Rate Ratio (SRR) and its 95% CI.

RESULTS

During the period 2011-2015 there were 5175 and 65,528 cases of TC diagnosed in PR and the US, respectively. The overall age-adjusted incidence rate of PTC was almost two-fold higher in PR than in the US (25.8/100,000 vs. 12.9/100,000). Among PR women, the incidence rate of PTC was 40.0/100,000 compared to 19.4/100,000 in US. PR women had 83% increased risk of being diagnosed with PTC than NHW women, a 2.25-fold increased risk than USH, and 3.45-fold increased risk than NHB women. For men, PR had 34% increased risk of being diagnosed with PTC than NHW men, 2.2-fold increased risk than USH men, and 3.2-fold higher risk than in NHB men.

CONCLUSION

Further research is needed to understand this disparity in the island. This research should address the extent of overdiagnosis in PR, the role of health insurance status and insurance type, characteristics of the healthcare delivery system as well as the role of patient and environmental factors.

Physical Activity and Thyroid Cancer Risk: A Case-Control Study in Catania (South Italy)

Background: The health benefits of physical activity are well established, but the association between physical activity and thyroid cancer remains poorly understood. The aim of the study was to investigate the relationship between physical activity and thyroid cancer in order to determine type, frequency, and duration of exercise needed to maximize prevention. Method: Cases, diagnosed from January 2009 to July 2018, and controls were enrolled at the University Hospital “Policlinico-Vittorio Emanuele” of Catania (South Italy). Logistic regression models were used to estimate the crude and adjusted odds ratios (ORs) and their 95% confidence intervals. Results: A total of 106 cases (91.2% papillary type) and 217 controls were enrolled. Physical activity was rare in Catania (32.8%) and was not correlated to risk of total thyroid cancer (OR: 0.997; 95% CI: 0.515–1.929). Conversely, walking every day for at least 60 minutes reduced the risk of thyroid cancer (OR: 0.357; 95% CI: 0.157–0.673). Conclusions: Our study showed that daily walking duration was associated with lower risk of thyroid cancer using a case-control study. Unfortunately, the frequency of physical activity often declines with age, particularly among the elderly, thus more research on physical activity adherence is needed to determine which approaches are most effective in promoting sustained physical activity participation.

Recreational Physical Activity and Differentiated Thyroid Cancer Risk: A Pooled Analysis of Two Case-Control Studies

PURPOSE

Physical activity has been hypothesized to influence cancer occurrence through several mechanisms. To date, its relation with thyroid cancer risk has been examined in relatively few studies. We pooled 2 case-control studies conducted in Cuba and Eastern France to assess the relationship between self-reported practice of recreational physical activity since childhood and thyroid cancer risk.

METHODS

This pooled study included 1,008 cases of differentiated thyroid cancer (DTC) matched with 1,088 controls (age range 9-35 and 17-60 years in the French and Cuban studies, respectively). Risk factors associated with the practice of recreational physical activity were estimated using OR and 95% CI. Logistic regressions were stratified by age class, country, and gender and were adjusted for ethnic group, level of education, number of pregnancies for women, height, BMI, and smoking status.

RESULTS

Overall, the risk of thyroid cancer was slightly reduced among subjects who reported recreational physical activity (OR = 0.8; 95% CI 0.5-1.0). The weekly frequency (i.e. h/week) seems to be more relevant than the duration (years).

CONCLUSION

Long-term recreational physical activity, practiced since childhood, may reduce the DTC risk. However, the mechanisms whereby the DTC risk decreases are not yet entirely clear.

Obesity Does Not Modify the Risk of Differentiated Thyroid Cancer in a Cytological Series of Thyroid Nodules

BACKGROUND

A possible impact of obesity on the risk of thyroid cancer has been postulated in some studies, but it remains controversial.

OBJECTIVE

To investigate the association between obesity and differentiated thyroid carcinoma in a population of unselected patients subjected to fine-needle aspiration cytology (FNAC) for thyroid nodules.

METHODS

We retrospectively evaluated the results of FNAC of thyroid nodules in 4,849 patients (3,809 females and 1,040 males; mean age 55.9 ± 14.1 years). Patients were stratified according to their body mass index (BMI). There were 1,876 (38.7%) normal-weight patients (BMI 18-24.9), 1,758 (36.2%) overweight (BMI 25-29.9), 662 (13.7%) grade 1 obese (BMI 30-34.9), 310 (6.4%) grade 2 obese (BMI 35-39.9) and 243 (5.0%) grade 3 obese (BMI >40).

RESULTS

The prevalence of suspicious or malignant nodules (Thy4/Thy5) did not differ across the 5 BMI groups, i.e. it was 6.8% in normal-weight patients, 6.3% in overweight patients, 6.3% in grade 1 obese patients, 4.0% in grade 2 obese patients and 4.2% in grade 3 obese patients (p = 0.29). The prevalence of Thy4/Thy5 nodules did not differ when males and females were evaluated separately (p = 0.22 and p = 0.12, respectively). A significant, lower rate of Thy4/5 cytology was observed in female patients with grade 2-3 obesity (odds ratio 0.51; 95% confidence interval 0.284-0.920; p = 0.009).

CONCLUSIONS

The results of this study, in a retrospective series of patients with thyroid nodules, do not confirm previous findings reporting an association between obesity and differentiated thyroid carcinoma. Thus, obese patients with nodular thyroid disease should be managed the same as normal-weight patients.

Annual Average Changes in Adult Obesity as a Risk Factor for Papillary Thyroid Cancer: A Large-Scale Case-Control Study

We evaluated the association between weight change in middle-aged adults and papillary thyroid cancer (PTC) based on a large-scale case-control study. Our study included data from 1551 PTC patients (19.3% men and 80.7% women) who underwent thyroidectomy at the 3 general hospitals in Korea and 15,510 individually matched control subjects. The subjects' weight history, epidemiologic information, and tumor characteristics confirmed after thyroidectomy were analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were determined for the annual average changes in weight and obesity indicators (body mass index (BMI), body surface area, and body fat percentage (BF%) in subjects since the age of 35 years. Subjects with a total weight gain ≥10 kg after age 35 years were more likely to have PTC (men, OR, 5.39, 95% CI, 3.88-7.49; women, OR, 3.36, 95% CI, 2.87-3.93) compared with subjects with a stable weight (loss or gain <5 kg). A marked increase in BMI since age 35 years (annual average change of BMI ≥0.3 kg/m/yr) was related to an elevated PTC risk, and the association was more pronounced for large-sized PTC risks (<1 cm, OR, 2.34, 95% CI, 1.92-2.85; ≥1 cm, OR, 4.00, 95% CI, 2.91-5.49, P heterogeneity = 0.005) compared with low PTC risks. Weight gain and annual increases in obesity indicators in middle-aged adults may increase the risk of developing PTC.

Adiposity and risk of thyroid cancer: a systematic review and meta-analysis

Thyroid cancer incidence has increased rapidly over time, as has obesity prevalence. A link between the two appears plausible, but the relation of adiposity to thyroid cancer remains incompletely understood. We performed a meta-analysis of adiposity measures and thyroid cancer using studies identified through October 2014. Twenty-one articles yielded data on 12,199 thyroid cancer cases. We found a statistically significant 25% greater risk of thyroid cancer in overweight individuals and a 55% greater thyroid cancer risk in obese individuals as compared with their normal-weight peers. Each 5-unit increase in body mass index (BMI), 5 kg increase in weight, 5 cm increase in waist or hip circumference and 0.1-unit increase in waist-to-hip ratio were associated with 30%, 5%, 5% and 14% greater risks of thyroid cancer, respectively. When evaluated by histologic type, obesity was significantly positively related to papillary, follicular and anaplastic thyroid cancers, whereas it revealed an inverse association with medullary thyroid cancer. Both general and abdominal adiposity are positively associated with thyroid cancer. However, relations with BMI vary importantly by tumour histologic type.

Leisure time physical activity and cancer risk: evaluation of the WHO's recommendation based on 126 high-quality epidemiological studies

BACKGROUND

The WHO has concluded that physical activity reduces the risk of numerous diseases. However, few systemic reviews have been performed to assess the role of leisure time physical activity (LTPA) in lowering the risk of cancer in a dose-dependent manner and furthermore the suitability of recommendation of physical activity by the WHO.

METHODS

A systematic review and meta-analysis was designed to estimate cancer risk by LTPA in binary comparison and in a dose-dependent manner. MEDLINE and Web of Science were searched up to 30 December 2014 without language restrictions. Reference lists were reviewed for potential articles.

RESULTS

A total of 126 studies were recruited into the meta-analysis. Overall, the total cancer risk was reduced by 10% in people who undertook the most LTPA as compared with those who did the least. Dose-response meta-analysis indicated that the current WHO recommendation (equal to an average of 10 metabolic equivalents of energy hours per week) induced a 7% (95% CI 5% to 9%) cancer reduction. Moreover, the protective role of LTPA against cancer becomes saturated at 20 metabolic equivalents of energy hours per week, with a relative risk of 0.91 (95% CI 0.88 to 0.93). Subanalyses results based on cancer types showed that LTPA only exhibited significant protection against breast cancer and colorectal cancer.

CONCLUSIONS

Our meta-analysis indicates that the current WHO recommendation of physical activity can result in a 7% reduction in cancer risk, which is mainly attributed to its protective role against breast cancer and colorectal cancer. Furthermore, two-fold of current recommendation level is considered to give its saturated protection against cancer.

Obesity and the risk of papillary thyroid cancer: a pooled analysis of three case-control studies

BACKGROUND

There is a correlation between temporal trends of obesity prevalence and papillary thyroid cancer (PTC) incidence in the United States. Obesity is a well-recognized risk factor for many cancers, but there are few studies on the association between obesity and PTC risk. We investigated the association between anthropometric measurements and PTC risk using pooled individual data from three case-control populations.

METHODS

Height and weight information were obtained from three independent case-control studies, including 1917 patients with PTC (1360 women and 557 men) and 2127 cancer-free controls from the United States, Italy, and Germany. Body mass index (BMI), body fat percentage, and body surface area (BSA) were calculated. An unconditional logistic regression model was used to calculate odds ratios (ORs) and confidence intervals (CIs) with respect to risk of PTC, adjusted by age, sex, race/ethnicity, and study site.

RESULTS

In the pooled population, for both men and women, an increased risk of PTC was found to be associated with greater weight, BMI, body fat percentage, and BSA, whereas a reduced risk of PTC was associated with greater height, in the pooled population for both men and women. Compared with normal-weight subjects (BMI 18.5-24.9 kg/m2), the ORs for overweight (BMI 25-29.9 kg/m2) and obese (BMI≥30 kg/m2) subjects were 1.72 [CI 1.48-2.00] and 4.17 [CI 3.41-5.10] respectively. Compared with the lowest quartile of body fat percentage, the ORs for the highest quartile were 3.83 [CI 2.85-5.15] in women and 4.05 [CI 2.67-6.15] in men.

CONCLUSION

Anthropometric factors, especially BMI and body fat percentage, were significantly associated with increased risk of PTC. Future studies of anthropometric factors and PTC that incorporate intermediate factors, including adiposity and hormone biomarkers, are essential to help clarify potential mechanisms of the relationship.

Obesity and thyroid cancer: a clinical update

BACKGROUND

In the last decade, significant contributions have been made to our knowledge on the connection between the thyroid and adipose tissue. Modern society is faced with climbing rates of obesity and metabolic syndrome, and there is accumulating evidence of an association between obesity and increased cancer risk. The aim of this review is to summarize clinical data on the association between thyroid cancer (TC) and obesity and briefly to present plausible hypotheses explaining this interplay.

SUMMARY

We performed a search on the PubMed database for studies published in English from 1980 to March 2013 using the terms "thyroid cancer," "obesity," and "body mass index." Although there is inconsistency among the clinical studies, it seems that overweight and obesity are related to a modestly increased TC risk. Various factors, such as sex, ethnicity, and body changes during certain life periods, for example adolescence, may influence the association between obesity and TC risk. There are preliminary data linking obesity with a less favorable clinicopathologic profile of TC. However, validation with larger multicenter studies is needed. The precise underlying mechanisms have not yet been elucidated, but the insulin-IGF axis and adipokines, such as leptin and adiponectin, might be implicated in the link between excess weight and TC.

CONCLUSIONS

Given the rising prevalence of TC and the development of obesity as an epidemic, it is important to clarify its connection with TC as well as the mediating pathways. However, unless this association is confirmed and causation proven, screening for TC in overweight and obese subjects-a rapidly increasing body of the general population-does not seem justified.

Physical activity, diabetes, and risk of thyroid cancer: a systematic review and meta-analysis

Thyroid cancer incidence has been increasing more rapidly over time than the occurrence of cancers of other sites, and interest in potential adverse relations of diabetes and lack of physical activity to thyroid cancer risk is accumulating. We conducted a systematic review and meta-analysis of published epidemiologic studies on the relations of physical activity and diabetes to thyroid cancer according to the Meta-analysis of Observational Studies in Epidemiology guidelines. Published studies were identified through a search in MEDLINE and EMBASE. Random-effects models were used to summarize thyroid cancer risk estimates comparing high versus low levels of physical activity, and separately, comparing individuals with diabetes versus those without diabetes. Meta-regression analyses were performed to evaluate potential effect modification by study design and thyroid cancer risk factors. Information was extracted from seven studies of physical activity and thyroid cancer and from six studies of diabetes and thyroid cancer. The number of individuals from studies on physical activity was 939,305 (yielding 2,250 incident thyroid cancer cases) and from studies on diabetes it was 960,840 (yielding 1,230 cases). The summary relative risk (RR) estimate from cohort and case-control studies combined indicated no association between physical activity and thyroid cancer (summary RR 1.06, 95 % confidence interval (CI) 0.79-1.42). Subgroup-analyses revealed a significant positive association between physical activity and thyroid cancer in cohort studies (summary RR 1.28; 95 % CI 1.01-1.63), whereas the relation was suggestively inverse in case-control studies (summary RR 0.70; 95 % CI 0.48-1.03; p for heterogeneity = 0.005). Individuals with diabetes showed a borderline statistically significant increased risk of thyroid cancer compared with those without diabetes (summary RR 1.17; 95 % CI 0.99-1.39). The relations of physical activity and diabetes to thyroid cancer were not modified by sex, number of adjustment factors, and adjustments for adiposity, smoking, and study quality. In this comprehensive systematic review and meta-analysis, no significant association between physical activity and thyroid cancer was found. Diabetes showed a suggestive positive relation with risk of thyroid cancer.