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Zaichick et al. J Cancer Metastasis Treat 2018;4:60 I http://dx.doi.org/10.20517/2394-4722.2018.52 Page 5 of 15

Table 3. Comparison of the mean values (M ± SEM) of the chemical element mass fractions (mg/kg, on drymass basis)in the
normal human thyroid (males and females combined) obtained by both instrumental neutron activation analysis with high
resolution spectrometry of short-lived radionuclides and inductively coupled plasma-atomic emission spectrometry methods
Element INAA-SLR (M 1 ) ICP-AES (M 2 ) ∆, %
Ca 1692 ± 109 1633 ± 108 3.5
K 6071 ± 306 6764 ± 298 -11.4
Mg 285 ± 17 308 ± 17 -8.1
Mn 1.35 ± 0.07 1.21 ± 0.07 10.4
Na 6702 ± 178 7154 ± 201 -6.7
ICP-AES: inductively coupled plasma-atomic emission spectrometry; M: arithmetic mean; SEM: standard error of mean; ∆ = [(M 1 - M 2 )/
M 1 ] × 100%

The comparison of our results with published data for Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S,
Si, Sr, V, and Zn mass fraction in normal and cancerous thyroid [45-74] is shown in Table 5.

The ratios of means and the difference between mean values of Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn,
Na, P, S, Si, Sr, V, and Zn mass fractions in normal and cancerous thyroid are presented in Table 6.

DISCUSSION
Precision and accuracy of results
A good agreement of our results for the Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Mg, Mn, Na, P, S, Sr, V, and Zn
mass fractions with the certified values of CRM IAEA H-4, INCT-SBF-4, INCT-TL-1, and INCT-MPH-2
[Tables 1 and 2] as well as the similarity of the means of the Ca, K, Mg, Mn, and Na mass fractions in the
normal human thyroid determined by both INAA-SLR and ICP-AES methods [Table 3] demonstrates an
acceptable precision and accuracy of the results obtained in the study and presented in Tables 4-6.

The mean values and all selected statistical parameters were calculated for twenty chemical elements (Al, B,
Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V, and Zn) mass fractions [Table 4]. The mass fraction
of Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V, and Zn were measured in all, or a major
portion of normal and cancerous tissue samples.

Comparison with published data
The means obtained for Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Mg, Mn, Na, P, S, Si, Sr, V, and Zn mass fraction,
as shown in Table 5, agree well with the medians of mean values reported by other research for the human
thyroid, including samples received from persons who died from different non-thyroid diseases [45-65] .
The mean obtained for Li is two orders of magnitude lower than the median of previously reported data.
Moreover, it is outside the range of previously reported means. The mean obtained for V is one order of
magnitude higher than the median of previously reported data, but it is inside the previously reported range
of means. A number of values for chemical element mass fractions were not expressed on a dry mass basis
[75]
by the authors of the cited references. Hence we calculated these values using published data for water 75%
[76]
and ash 4.16% on dry mass basis contents in thyroid of adults.
In cancerous tissues [Table 3] our results were within the range of means published for Br, Ca, Cu, Fe, I, Mg,
Mn, and Zn contents. The obtained means for V was approximately three orders of magnitude lower median
of previously reported mean [Table 5]. The obtained mean for Cl was almost one order of magnitude higher
than the only reported result and the mean for K was some higher than the median of previously reported
means and also higher than the upper level of the range of these means [Table 5]. No published data
referring Al, B, Ba, Li, Na, P, S, Si, and Sr contents of cancerous thyroid tissue were found.

The ranges of means of Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V, and Zn levels
reported in the literature for normal and for untreated cancerous thyroid vary widely [Table 5]. This can be