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Page 8 of 15 Zaichick et al. J Cancer Metastasis Treat 2018;4:60 I http://dx.doi.org/10.20517/2394-4722.2018.52

Table 6. Differences between mean values (M ± SEM) of Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V, and Zn
mass fraction (mg/kg, dry mass basis) in normal and cancerous thyroid
Thyroid tissue Ratio
Element Norm Cancer Student’s t-test U-test Cancer
n = 105 n = 41 P P to norm
Al 10.5 ± 1.8 33.0 ± 7.1 0.0083 ≤ 0.01 3.14
B 0.476 ± 0.058 2.21 ± 0.52 0.0062 ≤ 0.01 4.64
Ba 1.12 ± 0.15 1.42 ± 0.35 0.446 > 0.05 1.27
Br 14.9 ± 1.2 139 ± 36 0.0016 ≤ 0.01 9.33
Ca 1682 ± 106 3013 ± 699 0.076 ≤ 0.05 1.79
Cl 3400 ± 174 7699 ± 703 0.000013 ≤ 0.01 2.26
Cu 4.08 ± 0.14 14.5 ± 2.6 0.0017 ≤ 0.01 3.55
Fe 223 ± 10 255 ± 27 0.278 > 0.05 1.14
I 1841 ± 107 71.8 ± 10.1 0.00000000001 ≤ 0.01 0.039
K 6418 ± 290 10054 ± 877 0.00060 ≤ 0.01 1.57
Li 0.0208 ± 0.0022 0.0314 ± 0.0090 0.265 > 0.05 1.51
Mg 296 ± 16 478 ± 42 0.00043 ≤ 0.01 1.61
Mn 1.28 ± 0.07 2.01 ± 0.29 0.024 ≤ 0.01 1.57
Na 6928 ± 175 8576 ± 531 0.0069 ≤ 0.01 1.24
P 4290 ± 207 10493 ± 866 0.0000054 ≤ 0.01 2.45
S 8259 ± 263 9448 ± 429 0.027 ≤ 0.01 1.14
Si 50.8 ± 6.2 143 ± 42 0.047 ≤ 0.01 2.81
Sr 3.81 ± 0.34 6.26 ± 1.59 0.144 > 0.05 1.64
V 0.102 ± 0.005 0.0904 ± 0.0100 0.305 > 0.05 0.89
Zn 94.8 ± 4.2 96.9 ± 12.6 0.877 > 0.05 1.02
M: arithmetic mean; SEM: standard error of mean; statistically significant values are in bold

Role of chemical elements in malignant transformation of the thyroid
Characteristically, elevated or reduced levels of chemical elements observed in cancerous tissues are
discussed in terms of their potential role in the initiation and promotion of TC. In other words, using the low
or high levels of the chemical element in cancerous tissues researchers try to determine the carcinogenic role
of the deficiency or excess of each chemical element in investigated organ. In our opinion, abnormal levels
of many chemical elements in tumor could be the cause and also the effect of malignant transformation.
From the results of such kind of studies, it is not always possible to decide whether the measured decrease or
increase in chemical element level in pathologically altered tissue is the reason for alterations or vice versa.

Al
The trace element Al is not described as essential, because no biochemical function has been directly
connected to it. At this stage of our knowledge, there is no doubt that Al overload impacts negatively on
human health, including the thyroid function .
[79]
B
[80]
Trace element B is known to influence the activity of many enzymes . Numerous studies have
demonstrated beneficial effects of B on human health, including anti-inflammatorystimulus - which reduces
levels of inflammatory biomarkers, such as high-sensitivity C-reactive protein and tumor necrosis factor α;
as well as raises levels of antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and glutathione
[81]
peroxidase . Why B content in cancerous thyroid is higher than normal level and how an excess of B acts
on thyroid are still to be cleared.

Br
This is one of the most abundant and ubiquitous of the recognized trace elements in the biosphere. Inorganic
bromide is the ionic form of bromine which exerts therapeutic as well as toxic effects. An enhanced intake
of bromide could interfere with the metabolism of iodine at the whole-body level. In the thyroid gland the
[82]
biological behavior of bromide is more similar to the biological behavior of iodide . In our previous studies,