Vitamin C in the Management of Thyroid Cancer: A Highway to New Treatment?

Thyroid cancer (TC) is the most common endocrine malignancy, with an increased global incidence in recent decades, despite a substantially unchanged survival. While TC has an excellent overall prognosis, some types of TC are associated with worse patient outcomes, depending on the genetic setting. Furthermore, oxidative stress is related to more aggressive features of TC. Vitamin C, an essential nutrient provided with food or as a dietary supplement, is a well-known antioxidant and a scavenger of reactive oxygen species; however, at high doses, it can induce pro-oxidant effects, acting through multiple biological mechanisms that play a crucial role in killing cancer cells. Although experimental data and, less consistently, clinical studies, suggest the possibility of antineoplastic effects of vitamin C at pharmacological doses, the antitumor efficacy of this nutrient in TC remains at least partly unexplored. Therefore, this review discusses the current state of knowledge on the role of vitamin C, alone or in combination with other conventional therapies, in the management of TC, the mechanisms underlying this association, and the perspectives that may emerge in TC treatment strategies, and, also, in light of the development of novel functional foods useful to this extent, by implementing novel sensory analysis strategies.

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.

Histopathological prognosis of papillary thyroid carcinoma associated with nutritional status of vitamins A and E

BACKGROUND/OBJECTIVES

Experimental and clinical studies have shown that vitamins A and E can inhibit cancer formation and progression. The unfavourable status of these vitamins can represent risk factors for the disease. This study aimed to evaluate the associations between the nutritional status of vitamins A and E (serum levels and dietary intake) and histopathological outcomes in Papillary Thyroid Carcinoma (PTC) patients.

SUBJECTS/METHODS

We applied a cross-sectional study (2017-2018) and quantified retinol (ROH) and α-tocopherol (TOH) serum levels and vitamins dietary intake of 46 PTC patients. Serum vitamins were quantified by high efficiency liquid chromatography and vitamins dietary intake was analyzed by 24-hr dietary recalls.

RESULTS

Patients with lower ROH serum levels were more likely to present lymph node metastasis and/or angiolymphatic invasion (p = 0.025). In addition, higher vitamin A and vitamin E intake are related to the absence of extrathyroidal extension (p = 0.013) and lymph node metastasis (p = 0.007), respectively. Our findings suggest that a ROH serum level greater than 2.65 μmol/L in PTC patients may be a protective factor against the presence of lymph node metastasis and angiolymphatic invasion. In addition, vitamin A and E intake may protect against extrathyroidal extension and lymph node metastasis.

CONCLUSIONS

A favourable nutritional status (higher serum levels and/or intake) of vitamin A and E may be associated with less aggressive tumours in PTC patients.

Major dietary patterns and differentiated thyroid cancer

BACKGROUND

Differentiated Thyroid Cancer (DTC) is the most common endocrine cancer with an increasing trend worldwide. Dietary pattern as a modifiable factor may be associated with DTC.

OBJECTIVE

The present study aimed to evaluate the association between major dietary patterns and risk of DTC.

METHODS

A case control study was conducted among 309 clinic-based participants in northeast of Iran. Dietary data were then collected by a validated Food Frequency Questionnaire (FFQ). Further, codified data were analyzed by factor analysis and logistic regression analysis to identify the dietary patterns and to examine the association between dietary patterns and DTC, respectively.

RESULTS

According to our results, four major dietary patterns including western dietary pattern, traditional dietary pattern, transitional dietary pattern, and healthy dietary pattern were identified. The western dietary pattern was associated with increased odds of DTC after adjustment for potential confounders (OR = 2.79, 95% CI: 1.01-7.74). However, there was no association between other dietary patterns and DTC after adjustment.

CONCLUSIONS

In conclusion, the findings showed that western dietary pattern might be associated with DTC. Further studies are recommended to provide more conclusive evidences about the association between dietary patterns and DTC.

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.

Association between nutrient intake and thyroid cancer risk in Korean women

BACKGROUND/OBJECTIVES

The incidence of thyroid cancer has increased in many countries, including Korea. International differences in the incidence of thyroid cancer may indicate a role of diet, but findings from previous studies are inconclusive. Therefore, we aimed to investigate the roles of nutrients in thyroid cancer risk in Korean women.

SUBJECTS/METHODS

We conducted a case-control study comprising 113 cases and 226 age-matched controls. Nutrient intake was assessed using a validated food frequency questionnaire, and the association between nutrient intake and thyroid cancer risk was estimated using a logistic regression model.

RESULTS

We found that high calcium intake was associated with a reduced risk of thyroid cancer (OR [95% CI] = 0.55 [0.35-0.89]). Significant associations were observed among subjects who were older than 50 years, had low BMI, and had low calorie intake. However, other nutrients included in this study did not show any significant associations with thyroid cancer risk.

CONCLUSIONS

This study suggested a possible protective effect of calcium on thyroid cancer risk. Well-designed prospective studies are required to confirm these findings.

Dietary factors and the risk of thyroid cancer: a review

In the past few decades, the incidence of thyroid cancer has rapidly increased worldwide. Thyroid cancer incidence is relatively high in regions where the population's daily iodine intake is insufficient. While low dietary iodine has been considered as a risk factor for thyroid cancer development, previous studies found controversial results across different food types. Among different ethnic groups, dietary factors are influenced by various dietary patterns, eating habits, life-styles, nutrition, and other environmental factors. This review reports the association between dietary factors and thyroid cancer risk among ethnic groups living in different geologic regions. Iodine-rich food such as fish and shellfish may provide a protective role in populations with insufficient daily iodine intake. The consumption of goitrogenic food, such as cruciferous vegetables, showed a positive association with risk. While considered to be a risk factor for other cancers, alcohol intake showed a protective role against thyroid cancer. High consumption of meat such as chicken, pork, and poultry showed a positive association with the risk, but dairy products showed no significant association. Regular use of multivitamins and dietary nitrate and nitrite also showed a positive association with thyroid cancer risk. However, the study results are inconsistent and investigations into the mechanism for how dietary factors change thyroid hormone levels and influence thyroid function are required.

Antioxidant vitamins and chemoprevention

Free radicals play an important role in human carcinogenesis and the mechanism of their counteraction by antioxidant vitamins has been reviewed. It seems more likely that these vitamins work in concert rather than acting singly. Currently available data are compatible with the notion that these vitamins act as chemopreventives against some important cancers, e.g. carotenoids for lung cancer, ascorbic acid for salivary gland cancer, tocopherols for head and neck cancers etc. Thus, a greater consumption of fruits and vegetables should be encouraged as they are the natural sources of these chemopreventive, antioxidants along with other protective factors packaged by nature. However, much work still remains to be done to establish the role of antioxidant vitamins in carcinogenesis.

The effect of raw vegetable and fruit intake on thyroid cancer risk among women: a case–control study in South Korea

Thyroid cancer is the most common cancer among Korean women. However, there are few data on dietary factors related to thyroid cancer risk. The objective of the present study was to evaluate the association between raw vegetables and fruits intake and thyroid cancer in a case–control study. We included 111 histologically confirmed malignant thyroid cancer cases and 115 benign cases. Controls who did not have nodules in thyroid ultrasonography were matched to cases by age ( ± 2 years). Food and nutrient intakes were estimated using a quantitative FFQ with 121 items. Conditional logistic regression analysis was used to obtain OR and corresponding 95 % CI. The intake of total vegetables was not associated with malignant thyroid cancer, but inversely associated with benign cases. High raw vegetable intake was inversely associated with thyroid cancer risk both in malignant and benign cases (P for trend = 0·01 in both malignant and benign cases). Among fruits, persimmon intake had an inverse association with thyroid cancer risk in both malignant and benign cases (P for trend = 0·06 in malignant cases; P for trend = 0·01 in benign cases) and tangerine intake had an inverse association in malignant cases (P for trend = 0·03). The frequency of consumption of raw vegetables and persimmon also had a consistent inverse association in both malignant and benign cases. These results suggest that high consumption of raw vegetables, persimmons and tangerines may decrease thyroid cancer risk and help prevent early-stage thyroid cancer.

Risk factors and a predictive model for thyroid cancer in Korean women

BACKGROUND

Thyroid cancer incidence in Korean women has increased radically and is the highest in all cancer types. However, the rate of cancer screening among women is very low.

OBJECTIVE

The aim of the study was to determine the risk factors for thyroid cancer and to develop a predictive model based on these risk factors.

METHODS

The study design comprised a literature review and a case-control study. To construct a predictive model, the participants selected were 260 female outpatients diagnosed with malignant neoplasm of thyroid gland who had undergone thyroid removal surgery. A total of 259 people for the control group were selected by adopting a 5-year age-matching method.

RESULTS

From the literature review, 6 categories of risk factors were identified. Nine variables, including occupation, live(d) in coastal region, family history of thyroid cancer, history of benign thyroid tumor, menopause status and weight gain, number of full-term deliveries, abortion, exercise intensity, and stress, remained as statistically significant risk factors in the stepwise regression model. Regarding the predictive power of the model, the area under the receiver operating characteristic curve was .79, accuracy was .77, sensitivity was .89, specificity was .65, positive predictive value was .72, and negative predictive value was .85.

CONCLUSION

The predictive power of the model was relatively good, so it can be used to identify individuals at high risk for thyroid cancer.

IMPLICATIONS FOR PRACTICE

The predictive model can be used in promoting to participate in early cancer-screening tests. Thus, it will be possible to detect thyroid cancer in its earliest stage, diminish mortality, and improve quality of life.

Risk factors for thyroid cancer: an epidemiological review focused on nutritional factors

OBJECTIVES

The present review summarizes epidemiological evidence on risk factors for thyroid cancer (TC), in particular, nutritional factors.

METHODS

Searches of articles on the issue were conducted using MEDLINE.

RESULTS

Exposure to ionizing radiation, particularly during childhood, is the best-established risk factor for TC. There is also a strong association with history of benign nodules/adenoma or goiter. Iodine deficiency may induce an increasing incidence of benign thyroid conditions, but very high iodine intake also affects thyroid function and, possibly, TC risk. Among dietary factors, fish-the major natural source of iodine in human diet-is not consistently related to TC risk. High intake of cruciferous vegetables shows a weak inverse association with TC. Among other food groups, vegetables other than cruciferous are the only food group showing a favorable effect on TC, with an approximate 20% reduction in risk for subjects with the highest consumption. No effect on TC risk of alcohol, coffee, or other food-groups/nutrients emerged. Height and weight at diagnosis show a moderate positive association with TC risk.

CONCLUSION

At present, the only recognized measures for reducing TC risk is to avoid ionizing radiation and iodine deficiency, particularly in childhood and young women, and to increase vegetable consumption.

Changes in macrophage and lymphocyte functions in guinea-pigs after different amounts of vitamin E ingestion

Vitamin E is the main biological lipid-soluble antioxidant and plays a crucial role in the maintenance of the immune system. In the present work, twenty-one guinea-pigs (3-weeks-old) were distributed into three groups, which during 5 weeks ingested different amounts of vitamin E (/kg diet): 15 mg (low vitamin E diet), 150 mg (medium vitamin E diet; control) or 1500 mg (high vitamin E diet). The function of lymphocytes and macrophages were then studied. In macrophages obtained from the peritoneum several steps of the phagocytic process (chemotaxis, ingestion and superoxide anion production) were assayed, as well as chemotaxis and proliferation of peritoneal and spleen lymphocytes. The results indicate that with respect to the medium vitamin E diet, low ingestion of vitamin E causes a decrease in chemotaxis and production of superoxide anion by macrophages and an increase in the phagocytic capacity. With the high vitamin E diet an increase in macrophage and lymphocyte chemotaxis, superoxide anion production and lymphoproliferative capacity, as well as a decrease in phagocytosis, were observed. Therefore, diet supplementation with higher than usual levels of vitamin E appears to be beneficial for the immune system.

Thyroid microcarcinoma: prevalence, prognosis, and management

OBJECTIVE

To review the usual course of thyroid microcarcinoma (TMC) and the associated prognosis and treatment of affected patients.

METHODS

We discuss predisposing factors in the formation of TMC and the modulation of its behavior, diagnostic evaluation, and management options.

RESULTS

TMC, generally defined as a well-differentiated thyroid cancer less than or equal to 15 mm in diameter, has an estimated prevalence (based on autopsy studies) of about 5 to 10%. Studies, however, have shown that most of these cancers are smaller than 5 mm in diameter. The high prevalence of TMC in the general population contrasts with the rarity of thyroid cancers of greater size, which constitute less than 1% of malignant neoplasms in the United States. The frequent detection of TMC as a result of routine imaging of the neck for unrelated reasons and as a incidental finding in surgical specimens has raised a question about whether the management of TMC should differ from that for thyroid cancer of appreciable size. The uncertainty about optimal management of TMC is attributable to the small number of long-term follow-up studies as well as the common observation that patients usually have an excellent prognosis. Although in most patients harboring a TMC the cancer remains quiescent and never becomes clinically significant, in some cases TMC can demonstrate an aggressive course. Several variables, such as older age, multifocality, bilateral disease, and extrathyroidal spread at initial assessment, may have some adverse prognostic significance. After a partial surgical removal of the thyroid gland for TMC, the recurrence rate may be as high as 11%. Therefore, a treatment dilemma is caused by the low propensity of TMC for progression to clinically significant disease, yet the potential for recurrence and aggressive behavior in some cases.

CONCLUSION

In general, surgical resection of TMC is based on results of fine-needle aspiration biopsy and the rate of growth of the nodule. Aggressive management seems indicated in high-risk patients, particularly older patients, those with a history of radiation exposure, and those with multifocal disease, bilateral disease, or lymph node involvement.

Micronutrients, antioxidants, and carcinoma of the gallbladder

OBJECTIVES

Nutrient deficiency in developing countries can be considered a significant contributory factor modifying the multistage process of carcinogenesis. Studies from different parts of the world have shown the deficiency of various micronutrients to be significantly associated with cancer. This study was undertaken to test the above hypothesis in patients with carcinoma of the gallbladder.

METHODS

Selenium (Se), zinc (Zn), copper (Cu), manganese (Mn), ascorbic acid (vitamin C), and alpha-tocopherol (vitamin E) were estimated in the serum, bile, and gallbladder tissue of 30 patients each of carcinoma of the gallbladder (group-I), cholelithiasis (group-II), and only in the serum of 30 age- and sex-matched healthy controls (group-III). The minerals were analyzed by atomic absorption spectrophotometer and vitamins by spectrophotometry.

RESULTS

The mean serum levels of Se, Zn, Mn, vitamin E, and vitamin C were significantly lower (P < 0.001) in group-I when compared with groups II and III. The mean biliary levels of Se and Zn (0.29, 3.45 mg/L) were reduced significantly (P < 0.001) in group-I when compared with group II (0.51, 5.2 mg/L). Mean tissue levels of Se and Zn were also significantly lower (P < 0.001) in group I (2.75, 43.09 microg/g) compared to group II (3.90, 61.37 microg/g). However, no significant difference was observed in tissue concentration of Mn, vitamin C, and vitamin E. Cu levels and Cu/Zn ratio showed a highly significant (P < 0.001) increase in serum, bile, and gallbladder tissue in carcinoma of the gallbladder compared to the other two groups.

CONCLUSIONS

The data supports an association between lower levels of Se, Zn, vitamin E, and risk of carcinoma of the gallbladder and suggest that Cu/Zn ratio could be a useful parameter in evaluating the patients of carcinoma of the gallbladder.

Advances in the pathogenesis and treatment of thyroid cancer

Thyroidectomy remains the mainstay of treatment for thyroid carcinoma. The extent of surgical resection, however, remains controversial as most patients will have excellent long-term prognosis and because some of the standard staging and prognostic information are not available at the time of surgical resection. The different staging and risk group definitions for thyroid carcinoma are not superior to the Tumor-Node-Metastasis classification of the American Joint Commission in Cancer (AJCC), which is universally available and accepted and should be used to report treatment outcomes. Recent advances in the molecular pathogenesis of thyroid malignancy will help identify high-risk patients who would benefit from aggressive surgical resection and adjuvant treatment.