Adolescent and mid-life diet and subsequent risk of thyroid cancer in the NIH-AARP diet and health study

Broccoli Consumption and Risk of Cancer: An Updated Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

The scientific literature has reported an inverse association between broccoli consumption and the risk of suffering from several types of cancer; however, the results were not entirely consistent across studies. A systematic review and meta-analysis of observational studies were conducted to determine the association between broccoli consumption and cancer risk with the aim of clarifying the beneficial biological effects of broccoli consumption on cancer.

METHODS

PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library (CENTRAL), and Epistemonikos databases were searched to identify all published papers that evaluate the impact of broccoli consumption on the risk of cancer. Citation chasing of included studies was conducted as a complementary search strategy. The risk of bias in individual studies was assessed using the Newcastle-Ottawa Scale. A random-effects model meta-analysis was employed to quantitatively synthesize results, with the I2 index used to assess heterogeneity.

RESULTS

Twenty-three case-control studies (n = 12,929 cases and 18,363 controls; n = 31,292 individuals) and 12 cohort studies (n = 699,482 individuals) were included in the meta-analysis. The results suggest an inverse association between broccoli consumption and the risk of cancer both in case-control studies (OR: 0.64, 95% CI from 0.58 to 0.70, p < 0.001; Q = 35.97, p = 0.072, I2 = 30.49%-moderate heterogeneity; τ2 = 0.016) and cohort studies (RR: 0.89, 95% CI from 0.82 to 0.96, p = 0.003; Q = 13.51, p = 0.333, I2 = 11.21%-low heterogeneity; τ2 = 0.002). Subgroup analysis suggested a potential benefit of broccoli consumption in site-specific cancers only in case-control studies.

CONCLUSIONS

In summary, the findings indicate that individuals suffering from some type of cancer consumed less broccoli, suggesting a protective biological effect of broccoli on cancer. More studies, especially cohort studies, are necessary to clarify the possible beneficial effect of broccoli on several types of cancer.

Increasing Cancer in Adolescents and Young Adults: Cancer Types and Causation Implications

Purpose: This study aimed to identify cancer incidence trends in the United States and globally in adolescents and young adults (AYAs) 15-39 years of age, by sex, and to speculate on causes for trend changes. Methods: For the United States, SEER*Stat was used to obtain average annual percent change (AAPC) trends in cancer incidence during the period 2000-2019 among 395,163 AYAs. For global data, the source was the Institute of Health Metrics and Evaluation and its sociodemographic index (SDI) classification system. Results: In the United States, the invasive cancer incidence increased during the period 2000-2019 in both females (AAPC: 1.05, 95% CI: 0.90-1.20, p << 0.001) and males (AAPC: 0.56, 95% CI: 0.43-0.69, p << 0.001). A total of 25 and 20 types of cancers increased statistically significantly in female and male AYAs, respectively. Among potential causes for the increases, the obesity epidemic in the United States strongly correlates with the overall cancer increase in both its female (Pearson correlation coefficient R2 = 0.88, p = 0.0007) and male (R2 = 0.83, p = 0.003) AYAs, as does the most common malignancy in American AYAs, breast cancer (R2 = 0.83, p = 0.003). Worldwide, cancer incidence in the age group increased steadily during the period 2000-2019 among high-middle, middle, and low-middle SDI countries, but not in low SDI countries and with slowing of increase in high SDI countries. Conclusions: The increases and their age-dependent profiles implicate several causations that are preventable, including obesity, overdiagnosis, unnecessary diagnostic radiation, human papilloma virus infection, and cannabis avoidance. The United States is beginning to reverse the increasing incidence, and prevention efforts should be augmented accordingly.

Adolescent dietary patterns in relation to later prostate cancer risk and mortality in the NIH-AARP Diet and Health Study

BACKGROUND

Although adolescent diet has been proposed to contribute to prostate cancer (PCa) development, no studies have investigated the relation between adolescent dietary patterns and PCa risk or mortality.

METHODS

Using data from 164,079 men in the NIH-AARP Diet and Health Study, we performed factor analysis to identify dietary patterns at ages 12-13 years and then used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of total (n = 17,861), non-advanced (n = 15,499), advanced (n = 2362), and fatal PCa (n = 832).

RESULTS

Although not entirely consistent across analyses, a higher adolescent plant-based pattern (characterised by vegetables, fruits, and dark bread) score was associated with slightly reduced risks of total (fully adjusted HRQ5vs.Q1 = 0.93, 95% CI: 0.89-0.98, p trend=0.003) and non-advanced PCa (HR = 0.91, 95% CI: 0.87-0.96, p trend<0.001), whereas no associations were observed for advanced or fatal PCa, or for Western modern (characterised by sweets, processed meat, beef, cheese, and pizza) or Western traditional (characterised gravy, eggs, potatoes and white bread) patterns.

CONCLUSION

We found evidence to support a modest, protective role for a plant-based dietary pattern during adolescence on PCa risk. If confirmed in future studies, our findings may help to inform the development of new, primary prevention strategies for PCa.

Mediterranean Diet and Thyroid: An Interesting Alliance

The Mediterranean diet, recognized as being cultural heritage by UNESCO, is mostly plant-based and includes a high consumption of whole-grain, fruit, and vegetables with a moderate consumption of alcohol during meals. Thus, it provides a small amount of saturated fatty acids and a high quantity of antioxidants and fiber. For this reason, it has been considered to have an important role in preventing cardiovascular diseases, chronic kidney diseases, type 2 diabetes mellitus, and cancer, but its relationship with thyroid function and diseases is still under debate. The aim of this review was to search for the possible correlation between the Mediterranean diet and thyroid function, and to critically evaluate the pathophysiological link between selected food intake and thyroid disorders.

Is the Increasing Incidence of Thyroid Cancer in the Nordic Countries Caused by Use of Mobile Phones?

The International Agency for Research on Cancer (IARC) at the World Health Organization (WHO) categorized in 2011 radiofrequency (RF) as a possible human carcinogen, Group 2B. During use of the handheld wireless phone, especially the smartphone, the thyroid gland is a target organ. During the 21st century, the incidence of thyroid cancer is increasing in many countries. We used the Swedish Cancer Register to study trends from 1970 to 2017. During that time period, the incidence increased statistically significantly in women with average annual percentage change (AAPC) +2.13%, 95% confidence interval (CI) +1.43, +2.83%. The increase was especially pronounced during 2010-2017 with annual percentage change (APC) +9.65%, 95% CI +6.68, +12.71%. In men, AAPC increased during 1970-2017 with +1.49%, 95% CI +0.71, +2.28%. Highest increase was found for the time period 2001-2017 with APC +5.26%, 95% CI +4.05, +6.49%. Similar results were found for all Nordic countries based on NORDCAN 1970-2016 with APC +5.83%, 95% CI +4.56, +7.12 in women from 2006 to 2016 and APC + 5.48%, 95% CI +3.92, +7.06% in men from 2005 to 2016. According to the Swedish Cancer Register, the increasing incidence was similar for tumors ≤4 cm as for tumors >4 cm, indicating that the increase cannot be explained by overdiagnosis. These results are in agreement with recent results on increased thyroid cancer risk associated with the use of mobile phones. We postulate that RF radiation is a causative factor for the increasing thyroid cancer incidence.

External Radiation Dose, Obesity, and Risk of Childhood Thyroid Cancer After the Fukushima Daiichi Nuclear Power Plant Accident: The Fukushima Health Management Survey

BACKGROUND

The 2011 Great East Japan Earthquake led to a nuclear accident at Fukushima Daiichi Nuclear Power Plant. This study examines the associations of radiation dose and lifestyle factors with incidence of thyroid cancer in Fukushima.

METHODS

We designed a prospective study with 300,473 participants aged 18 years or younger, who underwent thyroid examinations from October 2011. Follow-up surveys were conducted through June 2017, and 245,530 participants (123,480 men and 122,050 women, 82% follow-up) received follow-up examinations. Fukushima Prefecture was divided into five areas based on individual external radiation dose. We calculated relative risks and 95% confidence intervals (CIs) for thyroid cancer in each area, with area of lowest dose as reference, using age-adjusted Poisson regression models. We also calculated risks associated with overweight and obesity.

RESULTS

The incidence per 100,000 for Groups A (highest dose), B, C, D, and E (lowest dose) were 13.5, 19.2, 17.3, 9.0, and 8.3, respectively. Compared with Group E, the age-adjusted risks (95% CIs) were 1.62 (0.59, 4.47) for group A, 2.32 (0.86, 6.24) for group B, 2.21 (0.82, 5.94) for group C, and 1.02 (0.36, 2.86) for group D. Obesity was positively associated with thyroid cancer incidence; the multivariable-adjusted risk of thyroid cancer was 2.23 (1.01, 4.90) for obese individuals compared with nonobese individuals.

CONCLUSION

Regional differences in radiation dose were not associated with increased risk of thyroid cancer among children in Fukushima within 4 to 6 years after the nuclear power plant accident. Obesity may be an important factor for further follow-up in Fukushima.

Phytoestrogens and Thyroid Cancer Risk: A Population-Based Case-Control Study in Connecticut

BACKGROUND

Very few previous studies have examined the relationship between thyroid cancer risk and intake of phytoestrogens (PE); furthermore, these studies have reached inconsistent results.

METHODS

We analyzed data from a population-based case-control study in Connecticut from 2010 to 2011, including 387 histologically confirmed thyroid cancer cases and 433 population-based controls, with compound data available concerning specific PEs. Multivariate unconditional logistic regression models were used to estimate the associations between specific PEs and the risk of thyroid cancer, adjusting for potential confounders.

RESULTS

An elevated risk of thyroid cancer was associated with moderate to high levels of coumestrol intake [OR = 2.48, 95% confidence interval (CI), 1.39-4.43 for 40-80 μg/day; OR = 2.41, 95% CI, 1.32-4.40 for 80-130 μg/day; and OR = 2.38, 95% CI, 1.26-4.50 for >200 μg/day compared with <40 μg/day], and the main elevation in risk appeared among microcarcinomas (≤1 cm). A decreased risk of papillary macrocarcinomas (>1 cm; OR = 0.26, 95% CI, 0.08-0.85 for 1,860-3,110 μg/day compared with <760 μg/day) was associated with moderate genistein intake among women.

CONCLUSIONS

Our study suggests that high coumestrol intake increases the risk of thyroid cancer, especially microcarcinomas, whereas moderate amounts of genistein intake appear to be protective for females with thyroid macrocarcinomas.

IMPACT

The study highlights the importance of distinguishing between microcarcinomas and macrocarcinomas in future research on the etiology of thyroid cancer.

Early Life Exposures and Adult Cancer Risk

Very little is known about the influence of early life exposures on adult cancer risk. The purpose of this narrative review was to summarize the epidemiologic evidence relating early life tobacco use, obesity, diet, and physical activity to adult cancer risk; describe relevant theoretical frameworks and methodological strategies for studying early life exposures; and discuss policies and research initiatives focused on early life. Our findings suggest that in utero exposures may indirectly influence cancer risk by modifying biological pathways associated with carcinogenesis; however, more research is needed to firmly establish these associations. Initiation of exposures during childhood and adolescence may impact cancer risk by increasing duration and lifetime exposure to carcinogens and/or by acting during critical developmental periods. To expand the evidence base, we encourage the use of life course frameworks, causal inference methods such as Mendelian randomization, and statistical approaches such as group-based trajectory modeling in future studies. Further, we emphasize the need for objective exposure biomarkers and valid surrogate endpoints to reduce misclassification. With the exception of tobacco use, there is insufficient evidence to support the development of new cancer prevention policies; however, we highlight existing policies that may reduce the burden of these modifiable risk factors in early life.

Consumption of fruits, vegetables and fruit juices and differentiated thyroid carcinoma risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Fruit and vegetable (F&V) intake is considered as probably protective against overall cancer risk, but results in previous studies are not consistent for thyroid cancer (TC). The purpose of this study is to examine the association between the consumption of fruits, vegetables, fruit juices and differentiated thyroid cancer risk within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. The EPIC study is a cohort including over half a million participants, recruited between 1991 and 2000. During a mean follow-up of 14 years, 748 incident first primary differentiated TC cases were identified. F&V and fruit juice intakes were assessed through validated country-specific dietary questionnaires. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression models adjusted for potential confounding factors. Comparing the highest versus lowest quartile of intake, differentiated TC risk was not associated with intakes of total F&V (HR: 0.89; 95% CI: 0.68-1.15; p-trend = 0.44), vegetables (HR: 0.89; 95% CI: 0.69-1.14; p-trend = 0.56), or fruit (HR: 1.00; 95% CI: 0.79-1.26; p-trend = 0.64). No significant association was observed with any individual type of vegetable or fruit. However, there was a positive borderline trend with fruit juice intake (HR: 1.23; 95% CI: 0.98-1.53; p-trend = 0.06). This study did not find any significant association between F&V intakes and differentiated TC risk; however a positive trend with fruit juice intake was observed, possibly related to its high sugar content.

A Cohort Study of Adolescent and Midlife Diet and Pancreatic Cancer Risk in the NIH-AARP Diet and Health Study

Given the long latency period of pancreatic cancer, exploring the influence of early and midlife exposures will further advance our understanding of the disease. We assessed associations between diet and pancreatic cancer incidence in the National Institutes of Health (NIH)-AARP (formerly American Association of Retired Persons) Diet and Health Study. In 1996, a total of 303,094 participants completed 2 food frequency questionnaires that assessed diet at ages 12-13 years and 10 years previously. We used Cox proportional hazards regression to estimate adjusted hazard ratios and 95% confidence intervals. Through the end of 2006, a total of 1,322 pancreatic cancer cases occurred (average follow up time = 10.1 years). When comparing the highest tertiles with the lowest, carbohydrate intake during adolescence (hazard ratio (HR) = 0.87, 95% confidence interval (CI): 0.76, 0.99), but not 10 years before baseline, was inversely associated with pancreatic cancer risk. Total fat intake 10 years before baseline was significantly associated with increased risk (HR = 1.17, 95% CI: 1.02, 1.34), while risk was higher for high fat intake during both adolescence and midlife. Calcium intake 10 years before baseline was associated with reduced risk (HR = 0.87, 95% CI: 0.76, 0.99), as was a change from low intake in adolescence to high intake in midlife (HR = 0.71, 95% CI: 0.54, 0.93). Our study found a number of dietary factors present during adolescence and midlife to be associated with pancreatic cancer.

The changing incidence of thyroid cancer

During the past few decades, the incidence of thyroid cancer has increased substantially in many countries, including the USA. The rise in incidence seems to be attributable both to the growing use of diagnostic imaging and fine-needle aspiration biopsy, which has led to enhanced detection and diagnosis of subclinical thyroid cancers, and environmental factors. The latest American Thyroid Association (ATA) practice guidelines for the management of adult patients with thyroid nodules and differentiated thyroid cancer differ substantially from the previous ATA guidelines published in 2009. Specifically, the problems of overdiagnosis and overtreatment of a disease that is typically indolent, where treatment-related morbidity might not be justified by a survival benefit, now seem to be acknowledged. As few modifiable risk factors for thyroid cancer have been established, the specific environmental factors that have contributed to the rising incidence of thyroid cancer remain speculative. However, the findings of several large, well-designed epidemiological studies have provided new information about exposures (such as obesity) that might influence the development of thyroid cancer. In this Review, we describe the changing incidence of thyroid cancer, suggest potential explanations for these trends, emphasize the implications for patients and highlight ongoing and potential strategies to combat this growing clinical and public health issue.