TABLE 1.
Characteristics of the studies included in this review.
| No. | Author, Year | Country | Study design | Case/subject Case/control Follow-up |
Age | Gender (male/ female) | Group comparisons | Main outcome | No. of cancer type | NOS |
| #01 | Fioretti et al. (49) | Italy | Case-control | 399/617 | 16–72/16–74 | Cases: 108/291; controls: 190/427 | Refined cereal: tertile (the highest vs. the lowest); β-carotene: tertile (the highest vs. the lowest). | 60% of thyroid cancer cases may be caused by some combination of identifiable factors or risk related factors, such as any history of benign thyroid disease, a history of radiation therapy, long-term residence in an area where goiter is prevalent, and some basic dietary indicators. | Papillary: 274; follicular: 69 | 8 |
| #02 | Galanti et al. (31) | Sweden | Case-control | 246/440 | 18–75 | Cases: 59/187; controls: 107/333 | Milk (glass), yogurt/acidified milk (dl), butter (tspn), all grains, all starchy foods, bread (slices), all fish, salt-water fish and shellfish, fresh-water fish, fish products, roe, caviar, all meat, all vegetables, vegetables (excluding cruciferous, cruciferous), all fruit (piece), apple, citrus fruit, coffee: tertiles alcohol: the highest tertile of alcohol intake compared with the lowest tertile (data not shown). | 1. High consumption of butter and cheese was associated with increased risks. 2. High consumption of cruciferous vegetables was associated with increased risk only in persons who ever lived in such areas. 3. A decreased risk was associated with consumption of iodized salt in northern Norway, and with use of iodized salt during adolescence among women. |
Papillary: 209; follicular: 37 | 7 |
| #03 | Kilfoy et al. (50) | America | Prospective cohort | 370/490194, 7 years | 50–71 | Cases: 170/200 | Nitrate and nitrite intake: highest quintile versus lowest quintile | 1. Among men, increasing nitrate intake was positively associated with thyroid cancer risk, however, we observed no trend with intake among women. 2. Nitrite intake was not associated with risk of thyroid cancer for either men or women. |
Papillary: 258; follicular: 64; medullary: 7 | 8 |
| #04 | Mack et al. (22) | America | Case-control | 292/292 | 15–54 | All female | Shellfish, saltwater fish, freshwater fish, turnips or rutabagas: the frequency of consumption (less than few times per year; few times per year; few times per month; few times per week or more); taking multivitamins: the frequency of consumption (never used regularly; >0–2 years; >2–10 years; >10 years); caffeinated coffee: the frequency of consumption (none; 1 cup per day; 2–3 cups per day; 4–5 cups per day; 6 or more cups per day); caffeinated tea, caffeinated sodas, beers, glasses of wine, shots of whiskey: the frequency of consumption (none; 1–2 cups per day; 3 or more cups per day): the frequency of consumption (none; 1–2 cups per day; 3 or more cups per day) | 1. Thyroid cancer risk was not associated with fish consumption, and consumption of certain vegetables, wine and tea reduced the risk of cancer. 2. Milk, beer and spirits, and coffee were not associated with thyroid cancer risk. |
Papillary: 240; follicular: 16 | 6 |
| #05 | Michikawa et al. (51) | Japan | Prospective cohort | 134/52545, 14.5 years | 40–59 | All female | Seaweed consumption: food-frequency questionnaire and divided into three categories: 2 days/week or less (reference); 3–4 days/week; and almost daily | This study identified a positive association between seaweed consumption and the risk of thyroid cancer (especially for papillary carcinoma) in postmenopausal women | Papillary: 113 | 8 |
| #06 | Nguyen et al. (52) | Korea | Prospective cohort | 138/13835, 7.6 years | 50.9 ± 7.7/ 53.3 ± 8.6 | Cases: 18/120; controls: 4904/8931 | Meal frequency: 3 meals/day for ≥5 days/week (yes or no); meal duration: ≥10 min (yes or no); meat and eggs: ≥5 times/week (no meat or amount of meat ≥ the size of 2 ping-pong balls and ≥1 egg or amount of meat < the size of 2 ping-pong balls and <1 egg); seafood ≥ 3 times/week (yes or no); tofu or soy milk ≥ 3 times/week (yes or no); vegetables, seaweed, mushrooms (except kimchi) every meal (yes or no); fruits ≥ 5 days/week (yes or no); milk or dairy products ≥ 5 days/week (yes or no); taste salty when eating out (yes or no); tend to eat salty food (yes or neutral or no); grilled meat frequency (never, sometimes, often, N/A (not applicable) | Consuming milk and/or dairy products 5 or more days a week and having a meal duration longer than 10 min could be protective factors against TC, especially in individuals aged ≥50 years, women and non-smokers. | Not mentioned | 7 |
| #07 | O’Grady et al. (7) | America | Prospective cohort | 592/565806, 4,406,634 person-years | 50–71 | N: 287944/194683; cases: 257/335 | Selenium, vitamin C, betacarotene, calcium, folate, vitamin E, vitamin D, magnesium, selenium, vitamin C, betacarotene, calcium, folate, vitamin E, vitamin D, magnesium, zinc: quintiles | No association between dietary intake of selenium or other micronutrients and thyroid cancer risk | Not mentioned | 8 |
| #08 | Takezaki et al. (53) | Japan | Case-control | 94/22666 | 20–79 | All female | Western breakfast, raw vegetable, fruit, green vegetable, cabbage, lettuce, carrot, tofu, miso soup, milk, egg, chicken, beef, pork, fish: intake frequency (low, medium, high) | 1. Frequent coffee consumption may be involved in a decreased risk of thyroid disease. 2. Other dietary factors did not show significant increased or decreased risk. |
Papillary:91; follicular: 3 | 7 |
| #09 | Xhaard et al. (54) | France | Case-control | 747/815 | <15 | Cases: 172/633; controls: 197/679 | Fresh dairy products or fresh milk: assessed in “never”/“ever” categories and by quartiles of quantities; leafy vegetable: assessed in “never”/“ever” categories and by quartile of quantities | 1. The DTC risk was slightly higher for participants who had consumed locally produced leafy vegetables. However, this association was not stronger in the more contaminated areas than in the others. 2. Conversely, the reported consumption of fresh dairy products was not statistically associated with DTC risk. |
Not mentioned | 8 |
| #10 | Xiao et al. (55) | America | Prospective cohort | 586/491254, 9 years | 50–71 | N: 234597/198593; cases: 252/334 | Dietary intakes of total flavonoids, flavonoid subtypes, and flavonoid-rich foods: quintiles.; tea: frequency of consumption (0; ≤1 cup/week; >1 cup/week –1 cup/day; >1–3 cup/day; >3 cup/day); oranges and tangelos, orange and grapefruit juice, legumes, grape, banana: median intake | 1. Thyroid cancer risk was inversely associated with dietary flavan-3-ols, but positively associated with flavanones. 2. Other classes of flavonoids and total flavonoids; were not associated with thyroid cancer risk. |
Not mentioned | 7 |
| #11 | Zamora-Ros et al. (56) | Spain | Prospective cohort | 748/476108, 14 years | 35–70 | Cases: 82/666 | Fish: quartiles (highest quartile vs. lowest quartile); shellfish: 3 groups (non-consumers and those below and above the median of consumers) | The intake of fish and shellfish was not associated with differentiated TC risk | Papillary: 601; follicular: 109 | 8 |
| #12 | Zamora-Ros et al. (56) | Spain | Prospective cohort | 748/476108, 14 years | 35–70 | Cases: 82/666 | Total F&V, vegetables, fruits, fruit juices: quartiles (highest quartile vs. lowest quartile) | 1. . No significant association between F&V intakes and differentiated TC risk. 2. . A positive trend with fruit juice intake was observed in TC. |
Papillary: 601; follicular: 109 | 8 |
| #13 | Zamora-Ros et al. (34) | Spain | Prospective cohort | 748/476108, 14 years | 35–70 | Cases: 82/666 | Coffee: cohort-wide quartiles. Tea: cohort-wide tertiles | Coffee and tea consumption were not associated with TC risk. | Papillary: 601; follicular: 109 | 8 |
| #14 | Zamora-Ros et al. (57) | Spain | Prospective cohort | 712/521324, 14 years | 35–70 | Cases: 74/638 | Tea, coffee, alcoholic beverages (beer and wine), sweetened beverages, and milk and dairy products: quartiles | Consumption of sweetened beverages was associated with a higher risk of differentiated thyroid cancer. | Papillary: 573; follicular: 108 | 8 |
| #15 | Jung et al. (23) | Korea | Case-control | 226/226 | 20–70 | All female | Total vegetables, raw vegetables, total fruits and all single fruits: quartiles of daily intake (g/d) and average consumption frequency (times/week) | High consumption of raw vegetables, persimmons and tangerines may decrease thyroid cancer risk and help prevent early-stage thyroid cancer. | 90% papillary | 7 |
| #16 | Braganza et al. (58) | America | Prospective cohort | 325/292152, 10 years | 12–13/41–62 | Cases: 143/182; controls: 170832/121320 | Grains, vegetables, fruit, dairy, chicken or turkey, red meat, canned tuna, butter and/or margarine and sweet baked goods, broccoli: the highest to the lowest quartiles | 1. Adolescent intakes of chicken/turkey and sweet baked goods were positively associated with thyroid cancer risk, while intake of butter/margarine was inversely associated with risk. 2. Mid-life intake of sweet baked goods was non-significantly associated with an increased risk of thyroid cancer but intake of butter/margarine was inversely associated with risk. 3. Among men, higher adolescent consumption of canned tuna was positively associated with risk of thyroid cancer, and greater mid-life intake of broccoli was associated with a twofold increased risk. 4. Iodine-rich foods may influence thyroid cancer risk. |
Papillary: 240; follicular: 60 | 8 |
| #17 | Sangsefidi et al. (46) | Iran | Case-control | 41/268 | 38.31 ± 12.52/ 41.82 ± 13.15 | Cases: 5/36; controls: 40/228 | Dietary pattern scores: tertiles | 1. The western dietary pattern significantly increases the odd of DTC. 2. The traditional, transitional, healthy dietary patterns did not have any association with DTC. |
Papillary: 33; follicular: 6; medullary: 2 | 7 |
| #18 | Aschebrook-Kilfoy et al. (59) | America | Prospective cohort | 164/73153, 9 years | 40–70 | All female | Nitrate and nitrite: the highest quartile vs. the lowest quartile | 1. No association between dietary nitrate intake and thyroid cancer as hypothesized. 2. An approximately 2-fold increased risk of thyroid cancer associated with the highest quartile of nitrite intake. |
Not mentioned | 9 |
| #19 | Cléro et al. (60) | France | Case-control | 229/371 | <56 | Cases: 26/203; controls: 47/324 | Dietary pattern (traditional Polynesian and Western): 3 categories (the highest tertile vs. the lowest tertile); goitrogenic food: tertiles (the highest tertile vs. the lowest tertile) | 1. No association between a western dietary pattern and the risk of thyroid cancer in French Polynesia. 2. A traditional Polynesian dietary pattern led to a weak reduced risk of thyroid cancer. |
Papillary: 177; follicular: 52 | 8 |
| #20 | Cléro et al. (61) | France | Case-control | 229/371 | <56 | Cases: 26/203; controls: 47/324 | Fish consumption (g/day), shellfish consumption (g/day), total consumption of food from the sea (g/day): tertiles dietary iodine: tertiles | A higher dietary iodine intake is significantly associated with a decreased risk of thyroid cancer | Not mentioned | 8 |
| #21 | Fiore et al. (4) | Italy | Case-control | 106/217 | 47 ± 14/42 ± 17 | Cases: 23/83; controls: 65/152 | Starchy foods; sweets cruciferous vegetables; non-cruciferous vegetables; meat and meat products; milk and dairy products; fish and seafood: 4-level scale (never, one time a week, 2–3 times a week, every day of the week).; Products rich in salt and fat, legumes, fruit: using cut off 2 (≤2 = never + 1 time a week and >2 = 2–3 times a week + every day); type (tap water, bottled water) and quantity of drinking water:1/2 L, 1 L, 2 or more liters; food supplements, iodized salt and vitamin: use (yes/no); caffeinated drinks: 3-level scale (never, 1–3 cups/die, 4– ≥6 cups/dies) | A diet with a limited consumption of starchy foods, products rich in salt, fat and sugar and a higher consumption of cruciferous/non-cruciferous vegetables, milk and dairy products and seafood could be protective toward thyroid cancer. | Not mentioned | 7 |
| #22 | Hallquist et al. (62) | Sweden | Case-control | 180/360 | 20–70 | Cases: 48/123 | Cabbage, green vegetables, root vegetables, meat, fish, shellfish: frequency (I: some times a week; II: several times a week) | 1. Eating cabbage or green vegetables did not affect thyroid cancer risk. 2. Intake of root vegetables after age 20 was associated with a significant increase in risk. |
Papillary: 107; follicular: 27; mixed (papillary/ follicular): 20; medullary: 7 | 8 |
| #23 | Haslam et al. (63) | America | Longitudinal cohort study | 27/108, 16.4 ± 3.1 years | Mean: 32.0/31.8 | Cases: 9/18; controls: 36/72 | PCB exposure: high (>7.0 mg), medium (1.01–7.0 mg), and low (≤1 mg); omega-3 fatty acid intake from Great Lakes fish: the highest quartile vs. the lowest quartile | No significant associations between fish consumption, short-term estimated omega-3 fatty acids, or estimated PCB consumption from Great Lakes fish and the development of thyroid cancer | Not mentioned | 7 |
| #24 | Hoang et al. (21) | Korea | Case-control | 117/173 | 52.5 ± 8.0/ 51.7 ± 8.1 | Cases: 6/111; controls: 33/140 | Dietary seaweed and iodine intakes: quartile groups of high (greater than median amount) and low (less than the median amount) consumption | The protective effects of dietary gim and iodine intake against thyroid cancer risk. | Not mentioned | 6 |
| #25 | Horn-Ross et al. (64) | America | Case-control | 608/558 | 20–74 | Fish consumption: the highest vs. lowest quintile | Multivitamin pills were associated with a reduced risk of papillary thyroid cancer. | Papillary: 544; follicular: 28; medullary: 5 | 9 | |
| #26 | Kim et al. (65) | America | Case-control | 462/498 | 21–84 | Cases: 87/375; controls: 1154/344 | Fiber, multivitamins, beta-carotene, vitamins A/C/E, and calcium supplements: the frequency (once a month, once a week, several times per week, daily) and duration (number of years) of use were collected. fruits (apples, pears, bananas, plums, melons, etc.) and vegetables (leafy greens, cabbage, carrot, broccoli, tomatoes, etc.): the quantity (number eaten) and frequency (number per day, week, or year) | 1. No significant associations were observed between dietary vitamin supplementation and overall thyroid cancer risk. 2. The associations between calcium supplements and risk of papillary thyroid cancer were different by tumor size. |
Not mentioned | 8 |
| #27 | Meinhold et al. (9) | America | Prospective cohort | 370/489789, 7.5 years | 50–71 | Cases: 170/200; controls: 291931/197858 | Alcohol (drinks): None; <1 per week; 1 – 6 per week; 1 – 2 per day; ≥2 per day | A potential protective role for alcohol consumption in thyroid cancer | Papillary: 258; follicular: 64 | 7 |
| #28 | Memon et al. (66) | Kuwait | Case-control | 313/313 | 15–44 | Cases: 75/238; controls: 75/2387 | Fish, shellfish, fish products, chicken, mutton and lamb, beef, cabbage, cauliflower, brussels, sprouts, broccoli, green vegetables, pickled, vegetables, fruits: low (never or occasional – few times a year), moderate (1 – 3 times per month or 1 day per week), and high consumption (2 – 4 days per week or 5 – 7 days per week) | 1. High consumption of processed fish products, fresh fish and chicken were independently associated with thyroid cancer with significant dose-response relationships. 2. No clear association emerged with consumption of cruciferous vegetables. |
Papillary: 186; follicular: 27; medullary: 3 | 7 |
| #29 | Myung et al. (67) | Korea | Case-control | 802/802 | 30–70 | Cases: 229/573; controls: 432/370 | Alcohol consumption (non-drinker; former drinker; current drinker; ever-drinker) | Alcohol consumption was associated with a decreased risk of TC. | Not mentioned | 9 |
| #30 | Preston-Martin et al. (68) | America | Case-control | 207/207 | 18–54 | All female | Saltwater fish, shellfish, freshwater fish: (never or infrequently; few times a month; few times a week; daily) | TC ate more fish and shellfish, but there was no trend with level of consumption. | Papillary: 173; follicular: 29; medullary: 4 | 7 |
| #31 | Wie et al. (69) | Korea | Prospective cohort | 136/7637, 7 years | 49.3 ± 8.0/ 48.4 ± 9.2 | Cases: 64/72; controls: 4180/3457 | Red meat and Na, vegetables and fruits: high intakes vs. low intakes; dietary risk factors: ranged from 0 to 4 points | Red meat consumption and Na (salt) intake were positively associated with thyroid cancer. | 8 | |
| #32 | Truong et al. (70) | France | Case-control | 293/345 | >18 | All female | Salt water fish, brackish water fish, seafood, dairy products, cruciferous vegetables, and starchy foods: quartile (the highest quartile vs. the lowest quartile) | 1. Consumption of fish and seafood is not related to thyroid cancer. 2. A positive association between the consumption of cruciferous vegetables and thyroid cancer. |
Papillary: 255; follicular: 38 | 7 |
| #33 | Wang et al. (71) | Japan | Prospective cohort | 94/35593, 13.2 years | 40–79 | All female | Seaweed intake frequency: 1–2 times/week or less, 3–4 times/week, and almost daily. | No association between seaweed intake and thyroid cancer incidence in premenopausal or in postmenopausal women. | Papillary: 64 | 8 |
| #34 | Ward et al. (32) | America | Prospective cohort | 45/21932, 19 years | 55–69 | All female | Dietary nitrate: (highest vs. lowest quartile) | 1. . An increased risk of thyroid cancer with higher average nitrate levels in public water supplies and with longer; consumption of water exceeding 5 mg/L nitrate-N. 2. . Increasing intake of dietary nitrate was associated with an increased risk of thyroid cancer and with the prevalence of hypothyroidism, but not hyperthyroidism. |
80% papillary; 18% follicular | 9 |
| #35 | Wingren et al. (72) | Sweden | Case-control | 104/387 | 20–60 | Cases: 11/93; controls: 187/200 | Intake of fish, intake of cruciferous vegetables: Several times a week; once a week; once a month; seldom/never; intake of shellfish: once a week or more; once a month; seldom/never | Factors associated with increased risk for female papillary cancer were low intake of cruciferous vegetables and seafood. | Papillary: 71; mixed (papillary/follicular): 33 | 8 |
| #36 | Chatenoud et al. (35) | Italy | Case-control | 428/3526 | <75 | Cases: 116/312; controls: 2069/1457 | Refined-cereal intake: the highest tertile vs. the lowest tertile | Consumption of refined cereals was associated with an increased risk of cancers of the large bowel, the stomach, and other selected digestive and non-digestive sites. | Not mentioned | 8 |
| #37 | Liang et al. (5) | America | Case-control | 390/436 | 21–84 | Cases: 71/319; controls: 128/309 | Starchy foods and desserts: the quartile (lowest quartile as the reference group). Fruits and vegetables: the quartile (lowest quartile as the reference group). High protein and fat: the quartile (lowest quartile as the reference group). | 1. A significant negative association between diet patterns rich in fruits and vegetables and TC risk, especially among women aged 50 years or older. 2. While high in starchy foods and desserts may be positively and negatively associated with TC risk among men and women, respectively |
Papillary: 329; follicular: 50; medullary: 9 | 8 |
TC, thyroid cancer; DTC, differentiated thyroid cancer; BMI, body mass index; PCB, polychlorinated biphenyl.