CANCER PROGNOSTICS AND DIAGNOSTICS (CPD)

Distinguishing Malignant from Benign Prostate using Chemical Elemental Content / Calcium Ratios in Prostatic Tissue



Vladimir Zaichick1*,Sofia Zaichick22


1Radionuclide Diagnostics Department, Medical Radiological Research Centre, Koroleva Str.- 4, Obninsk 249036, Kaluga Region, Russia
2Department of Medicine, University of Illinois College of Medicine, Chicago, IL 60612, USA

*Corresponding Author:Vladimir Zaichick, Professor, CChem, FRSC, 4, Koroleyva St., MRRC, Obninsk 249036, Russia, ; TEL::+748-439-60289 ; FAX::+748-439-60289;E-mail:vezai@obninsk.com


Citation:Vladimir Zaichick, Sofia Zaichick (2016) Distinguishing Malignant from Benign Prostate using Chemical Elemental Content / Calcium Ratios in Prostatic Tissue. Cancer Prog Diagn1:103.


Copyright: :© 2016 Vladimir Zaichick, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Received date:October 04, 2016; Accepted date:November 08, 2016; Published date:November 12, 2016


Abstract

The aim of the study was the development of new highly precise testing methods for early diagnosis of prostate cancer.For this purpose, the values of Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal (n=37), benign hypertrophic (n=11) and cancerous (n=11) human prostate gland were investigated by non-destructive instrumental neutron activation analysis. Mean values standard error of mean (MSΕΜ) for mass fraction ratios in the normal tissue were as follows: (Br/Ca)•102 1.440.21, K/Ca 5.690.38, Mg/Ca 0.5110.045, (Mn/Ca)•103 0.6230.062, and Na/Ca 5.580.48, respectively. It was observed that in benign hypertrophic tissues the Br/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios do not differ from normal levels while the K/Ca ratio is significantly higher. In cancerous tissue the Br/Ca, K/Ca, Mn/Ca, and Na/Ca ratios are significantly higher than in normal and benign hypertrophic prostate. It was shown that the Br/Ca and Mn/Ca mass fraction ratios are the most informative for a differential diagnosis among all investigated mass fraction ratios. Finally, we propose to use the estimation of Mn/Ca mass fraction ratios in a needle-biopsy core as an accurate tool to diagnose prostate cancer. Sensitivity, specificity, and accuracy of this test were (100-9)%, (100-2)%, and (100-2)%, respectively.Obtained data allowed us to adequately evaluate the importance of chemical elemental content ratios for the diagnosis of prostate cancer.


Key words:

chemical elements, chemical elemental mass fraction ratios; prostate; benign prostatic hypertrophy; prostatic carcinoma; neutron activation analysis

Introduction

The prostate gland may be a source of many health problems in men past middle age, the most common being benign prostatic hyperplasia (BPH), and prostatic carcinoma (PCa). BPH is a noncancerous enlargement of the prostate gland leading to obstruction of the urethra and can significantly impair quality of life [1]. The prevalence of histological BPH is found in approximately 50-60% of males age 40-50, in over 70% at 60 years old and in greater than 90% of men over 70 [2, 3]. In many Western industrialized countries, including North America, PCa is the most frequently diagnosed form of noncutaneous malignancy in males and, except for lung cancer, is the leading cause of death from cancer [4-9]. Although the etiology of BPH and PCa is unknown, some electrolytes and trace elements have been highlighted in the literature in relation to the development of these prostate diseases [10-29].


Electrolytes and trace elements have essential physiological functions such as maintenance and regulation of cell function and signalling, gene regulation, activation or inhibition of enzymatic reactions, neurotransmission, and regulation of membrane function. Essential or toxic (mutagenic, carcinogenic) properties of chemical elements depend on tissue-specific need or tolerance, respectively [30]. Excessive accumulation, deficiency or an imbalance of the chemical elements may disturb the cell functions and may result in cellular degeneration, death and malignant transformation [31].


In reported studies, significant changes of chemical element contents in hyperplastic and cancerous prostate in comparison with those in the normal prostatic tissue were observed [32-56]. Moreover, a informative value of Zn content as a tumor marker for PCa diagnostics was shown by us [57,58]. Hence it is possible that besides Zn, some other chemical elements also can be used as tumor markers for distinguish between benign and malignant prostate.


Current methods applied for measurement of chemical element contents in samples of human tissue include a number of methods. Among these methods the instrumental neutron activation analysis with high resolution spectrometry of short-lived radionuclides (INAA-SLR) is a non-destructive, sensitive, and prompt technique. It allows measure the chemical element contents in a few milligrams tissue without any treatment of sample. Analytical studies of the Br, Ca, K, Mg, Mn, and Na contents in normal, BPH and PCa tissue were done by us using INAA-SLR [15,21,28,50,55]. Nondestructive method of analysis avoids the possibility of changing the content of chemical elements in the studied samples [59-62], which allowed for the first time to obtain reliable results. In particular, it was shown that the average mass fraction of Ca in BPH tissue does not differ from normal level [54], but in PCa tissues it is 3.4 times lower than in healthy prostatic tissue [50]. Moreover, it was shown in our previous studies that in a normal prostate tissue mass fraction of some chemical elements tend to be correlated with Ca, while in BPH and PCa tissues these relationships are partially broken or changed [50,53,55]. Obtained results formed the basis for a new method for differential diagnosis of BPH and PCa, the essence of which was to determine the chemical elemental content / Ca content ratios in the material of transrectal needle biopsy of prostate indurated site, because, in comparison with the absolute values of chemical element contents, using their content ratios is more suitable for diagnostics.


Therefore, the present study had three aims. The main objective was to assess the Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in intact prostate of healthy men aged over 40 years and in the prostate gland of age-matched patients, who had either BPH or PCa, using data about the Br, Ca, K, Mg, Mn, and Na contents obtained by INAA-SLR analysis. The second aim was to compare the levels of elemental content ratios in normal, hyperplastic, and cancerous prostate, and the third aim was to evaluate the elemental content ratios for diagnosis of prostate cancer. All studies were approved by the Ethical Committees of the Medical Radiological Research Centre, Obninsk.


Material and Methods

Samples

All patients studied (n=22) were hospitalized in the Urological Department of the Medical Radiological Research Centre. Transrectal puncture biopsy of suspicious indurated regions of the prostate was performed for every patient, to permit morphological study of prostatic tissue at these sites and to estimate their chemical element contents. In all cases the diagnosis has been confirmed by clinical and morphological results obtained during studies of biopsy and resected materials. The age of 11 patients with BPH ranged from 56 to 75 years, the mean being 66.86.5 (MSD) years. The 11 patients aged 51-78 suffered from PCa. Their mean age was 67.79.9 (MSD) years.


Intact (Norm) prostate samples were removed at necropsy from 37 men aged 41-79 who had died suddenly. Their mean age was 5511 (MSD) years. The majority of deaths were due to trauma. Tissue samples were collected from the peripheral zone of dorsal and lateral lobes of their prostates, within 2 days of death and then the samples were divided into two portions. One was used for morphological study while the other was intended for chemical element analysis. A histological examination was used to control the age norm conformity, as well as to confirm the absence of microadenomatosis and latent cancer [15,21,28].


Sample preparation, instrumentation, methods and certified reference materials

Details of sample preparation, the relevant nuclear reactions, radionuclides, gamma energies, methods of analysis, equipment, and the results of quality control were presented in our earlier publications concerning the chemical elements of human prostate investigated by INAA-SLR [15,21,28,50,55,63].


Computer programs and statistic

A dedicated computer program for INAA mode optimization was used [64]. All prostate samples for INAA-SLR were prepared in duplicate and mean values of elemental content ratios were used in final calculation. Using the Microsoft Office Excel software, the summary of statistics, arithmetic mean, standard deviation, standard error of mean, minimum and maximum values, median, percentiles with 0.025 and 0.975 levels was calculated for chemical element mass fraction ratios in normal, benign hyperplastic and cancerous prostate tissue. The difference in the results between BPH and Norm, PCa and Norm, and PCA and BPH was evaluated by Student’s t-test. For the construction of “individual data sets for Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal, benign hypertrophic and cancerous prostate” diagrams the Microsoft Office Excel software was also used.


Results

Table 1: Some statistical parameters of Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal, benign hypertrophic and cancerous prostate.

.
Tissue Mass fraction ratio Mean SD SEM Min Max Median Per.
0.025
Per.
0.975
Normal (n=37)
(Br/Ca)•102 1.44 0.90 0.21 0.333 4.00 1.36 0.436 3.69
K/Ca 5.69 1.74 0.38 2.50 8.23 5.92 2.52 8.20
Mg/Ca 0.511 0.211 0.045 0.229 1.03 0.449 0.242 0.932
(Mn/Ca)•103 0.623 0.256 0.062 0.100 1.078 0.592 0.192 1.05
Na/Ca 5.58 2.24 0.48 1.73 10.6 5.51 2.29 10.3
BPH (n=11)
(Br/Ca).102 1.76 1.11 0.33 0.454 3.65 1.70 0.519 3.55
K/Ca 7.69 2.69 0.81 4.62 12.2 7.14 4.79 12.0
Mg/Ca 0.613 0.148 0.045 0.397 0.871 0.574 0.424 0.868
(Mn/Ca).103 0.626 0.228 0.069 0.335 1.03 0.591 0.357 1.01
Na/Ca 6.21 2.33 0.70 3.02 9.25 6.66 3.03 9.07
PCa (n=11)
(Br/Ca).102 18.8 10.1 3.0 1.52 34.1 18.8 3.21 33.4
K/Ca 13.5 3.76 1.14 7.22 18.2 13.9 7.73 18.1
Mg/Ca 0.508 0.271 0.086 0.169 1.04 0.463 0.192 0.989
(Mn/Ca).103 11.2 6.9 2.1 1.30 22.3 11.0 1.66 21.5
Na/Ca 11.8 3.8 1.2 4.67 17.2 11.1 5.39 16.8

M - arithmetic mean; SD – standard deviation; SEM – standard error of mean; Min – minimum value; Max – maximum value; Per. 0.025 – percentile with 0.025 level; Per. 0.975 – percentile with 0.975 level, n - number of samples.


Table 1 presents certain statistical parameters (arithmetic mean, standard deviation, standard error of mean, minimal and maximal values, median, percentiles with 0.025 and 0.975 levels) of the Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal, benign hypertrophic and cancerous prostate.The ratios of means and the reliability of difference between mean values of Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal, benign hypertrophic and cancerous prostate are presented in Table 2.



Table 2: Ratio of means and the reliability of difference between mean values of Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal, benign hypertrophic and cancerous prostate

.
Mass fraction ratio BPH and Normal (N) PCa and Normal (N) PCa and BPH
Ratio
BPH/N
Student’s t-test Ratio PCa/N Student’s t-test Ratio PCa/BPH Student’s t-test
(Br/Ca)•102 1.22 p=0.44 13.1 p=0.00019 10.7 p=0.00022
K/Ca 1.35 p=0.041 2.37 p=0.000026 1.76 p=0.00060
Mg/Ca 1.20 p=0.12 0.99 p=0.63 0.83 p=0.16
(Mn/Ca).103 1.00 p=0.97 18.0 p=0.00051 17.9 p=0.00051
Na/Ca 1.11 p=0.46 2.11 p=0.00021 1.90 p=0.00069

Fig. 1 depicts individual data sets for Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in all investigated samples of normal, benign hypertrophic and cancerous prostate.


Discussion

As was shown by us [15,21,28]the use of CRM IAEA H-4 as a certified reference material for the analysis of samples of prostate tissue can be seen as quite acceptable. Good agreement of the Br, Ca, K, Mg, Mn, and Na contents analyzed by INAA-SLR with the certified data of CRM IAEA H-4 [15,21,28]indicates an acceptable accuracy of the results obtained in the study of elemental content ratios of the prostate presented in Fig. 1 and Tables 1 and 2.


The mean values and all selected statistical parameters were calculated for 5 mass fraction ratios (Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca) (Table 1). The mass fraction ratios of these elements were calculated for all samples of normal, BPH and PCa prostates. The results presented in Table 1 did not show substantial differences between the arithmetic means and the medians, which indicate a normal distribution of the investigated elemental content ratios. These findings allowed us to compare the means of mass fraction ratios in normal, BPH and PCa prostate using Student’s t-test. No published data referring to mass fraction ratios of chemical elements in the human prostate was found Figure 1


Figure 1
Figure 1 :Individual data sets for Br, Ca, K, Mg, Mn, and Na mass fractions in samples of normal (1), benign hypertrophic (2) and cancerous (3) prostate.

From Table 2, it is observed that in benign hypertrophic tissues the Br/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios do not differ from normal levels while the K/Ca ratio is higher (p=0.041). In cancerous tissue the Br/Ca (p=0.00019), K/Ca (p=0.000026), Mn/Ca (p=0.00051), and Na/Ca (p=0.00021) ratios are significantly higher than in normal parenchyma of the prostate. All these mass fraction ratios show similar variations in cancerous tissues when compared with benign hypertrophic tissues of the prostate. The Mg/Ca mass fraction ratio is maintained a stable level which does not change with benign hypertrophic and malignant transformation of prostate.


Analysis of elemental content ratios in prostate tissue could become a powerful diagnostic tool. To a large extent, the resumption of the search for new methods for early diagnosis of PCa was due to experience gained in a critical assessment of the limited capacity of the prostate specific antigen (PSA) serum test [65]. In addition to the PSA serum test and morphological study of needle-biopsy cores of the prostate, the development of other highly precise testing methods seems to be very useful. Experimental conditions of the present study were approximated to the hospital conditions as closely as possible. In all cases we analyzed a part of the material obtained from a puncture transrectal biopsy of the indurated site in the prostate. Therefore, our data allow us to evaluate adequately the importance of elemental content ratios for the diagnosis of PCa. As is evident from individual data sets (Fig. 1), the Br/Ca and Mn/Ca mass fraction ratios are the most informative for a differential diagnosis. For example, if 1.2 is the value of (Mn/Ca)•103mass fraction ratio assumed to be the lower limit for PCa (Fig. 1) and an estimation is made for “PCa or intact and BPH tissue”, the following values are obtained:


Sensitivity = {True Positives (TP)/[TP + False Negatives (FN)]} •100% = (100-9)%;


Specificity = {True Negatives (TN)/[TN + False Positives (FP)]} •100% = (100-2)%;


Accuracy=[(TP+TN)/(TP+FP+TN+FN)] •100% = (100-2)%.


The number of people (samples) examined was taken into account for calculation of confidence intervals [66].In other words, if Mn/Ca mass fraction ratio in a prostate biopsy sample does not lower 1.2, one could diagnose a malignant tumor with an accuracy of (100-2)%. Thus, using the (Mn/Ca)-test makes it possible to diagnose cancer in (100-9)% cases (sensitivity).


The same way parameters of the importance (sensitivity, specificity and accuracy) of Br/Ca mass fraction ratio for the diagnosis of PCa were calculated. If 5.0 is the values of (Br/Ca)•102 mass fraction ratios assumed to be the lower limit for PCa (Fig.1) and an estimation is made for “PCa or intact and BPH tissue”, the following values are obtained: sensitivity (919)%, specificity (100-2)%, and accuracy (982)%; It should be noted, however, that Br is a component of many tranquilizers. It is possible that the increase in Br content could be explained by uncontrolled use of tranquilizers in the group of PCa patients. Therefore, for diagnostic purposes, data for Br/Ca mass fraction ratio should be used with caution.


Mass fraction ratios of Mn/Ca and Br/Ca in the needle-biopsy cores could be used as a tool to diagnose PCa and are comparable with characteristics of the Zn mass fraction-test [57,58]. However, it is our opinion that application of the elemental content ratios is more suitable for PCa diagnosis. Elemental mass fraction depends on the sample mass, which decreases with loss of its moisture. The needle-biopsy core is a small piece of tissue with a relatively high "surface/volume" ratio. After sampling, it begins to lose mass very fast. Weight loss of samples depends on the humidity of operating and store rooms [59]. Thus, it is very difficult to determine the fresh mass of needle-biopsy cores and to calculate the precise mass fraction of chemical elements. Sample freeze-dry, storage in air-tight vials until weighing, and then calculating mass fraction on dry mass basis is the only possible method that eliminates the variation in sample mass. Conversely, accuracy of elemental content ratios does not depend on sample mass and changes in moisture content. Therefore, this method does not require dry samples. Moreover, the use of the relations between mass fractions of chemical elements is particularly promising for the development of in vivo diagnostic methods, including the diagnosis of PCa.


Conclusion

In this work, mean values of Br/Ca, K/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios in normal, benign hypertrophic and cancerous prostate were calculated using data of INAA-SLR. It was observed that in benign hypertrophic tissues the Br/Ca, Mg/Ca, Mn/Ca, and Na/Ca mass fraction ratios do not differ from normal levels while the K/Ca ratio is rather higher. In cancerous tissue the Br/Ca, K/Ca, Mn/Ca, and Na/Ca ratios are significantly higher than in normal and benign hypertrophic prostate. It was shown that the Br/Ca and Mn/Ca mass fraction ratios are the most informative for a differential diagnosis among all investigated mass fraction ratios. Finally, we propose to use the estimation of Mn/Ca mass fraction ratios in a needle-biopsy core as an accurate tool to diagnose prostate cancer.


Acknowledgements

We are grateful to Dr. Tatyana Sviridova, Medical Radiological Research Center, Obninsk, and to the late Prof. A.A. Zhavoronkov, Institute of Human Morphology, Russian Academy of Medical Sciences, Moscow, for supplying prostate samples.


References

  1. Kirby RS (2000) The natural history of benign prostatic hyperplasia: what have we learned in the last decade? Urology 56: 3-6. [crossref]
  2. Roehrborn C, McConnell J (2002) Etiology, pathophysiology, epidemiology and natural history of benign prostatic hyperplasia. In: Walsh P, Retik A, Vaughan E, Wein A (eds.). Campbell’s Urology. Saunders, Philadelphia 8: 1297-1336.
  3. Lepor H (2005) Pathophysiology of benign prostatic hyperplasia in the aging male population. Rev Urol 7: S3-3S12. [crossref]
  4. Oliver SE, Gunnell D, Donovan JL (2000) Comparison of trends in prostate-cancer mortality in England and Wales and the USA. Lancet 355: 1788-1789. [crossref]
  5. Kumar RJ, Barqawi AB, Crawford ED (2004) Epidemiology of prostate cancer. Business Briefing: US Oncology Review 1-6.
  6. Maddams J, Brewster D, Gavin A, Steward J, Elliott J, et al. (2009) Cancer prevalence in the United Kingdom: estimates for 2008. Br J Cancer 101: 541-547. [crossref]
  7. Lutz JM, Francisci S, Mugno E, Usel M, Pompe-Kirn V, et al. (2003) Cancer prevalence in Central Europe: the EUROPREVAL Study. Ann Oncol 14: 313-322. [crossref]
  8. Möller T, Anderson H, Aareleid T, Hakulinen T, Storm H, et al. (2003) Cancer prevalence in Northern Europe: the EUROPREVAL study. Ann Oncol 14: 946-957.[crossref]
  9. De Angelis R, Grande E, Inghelmann R, Francisci S, Micheli A, et al. (2007) Cancer prevalence estimates in Italy from 1970 to 2010. Tumori 93: 392-397.[crossref]
  10. Waalkes MP, Rehm S (1994) Cadmium and prostate cancer. J Toxicol Environ Health 43: 251-269.[crossref]
  11. Zaichick V, Zaichick S (1999) Role of zinc in prostate cancerogenesis. In: Anke M, et al. (eds). Mengen und Spurenelemente. 19. Arbeitstagung. Friedrich-Schiller-Universitat, Jena 104-115.
  12. Platz EA, Helzlsouer KJ (2001) Selenium, zinc, and prostate cancer. Epidemiol Rev 23: 93-101.[crossref]
  13. Zaichick V (2004) INAA and EDXRF applications in the age dynamics assessment of Zn content and distribution in the normal human prostate. J Radioanal Nucl Chem 262: 229-234.
  14. Gray MA, Centeno JA, Slaney DP, Ejnik JW, Todorov T, et al. (2005) Environmental exposure to trace elements and prostate cancer in three New Zealand ethnic groups. Int J Environ Res Public Health 2: 374-384.[crossref]
  15. Zaichick S, Zaichick V (2011) INAA application in the age dynamics assessment of Br, Ca, Cl, K, Mg, Mn, and Na content in the normal human prostate. J Radioanal Nucl Chem 288: 197-202.
  16. Zaichick S, Zaichick V (2011) The effect of age on Ag, Co, Cr, Fe, Hg, Sb, Sc, Se, and Zn contents in intact human prostate investigated by neutron activation analysis. Appl Radiat Isot 69: 827-833.
  17. Zaichick S, Zaichick V (2011) The Br, Fe, Rb, Sr, and Zn content and interrelation in intact and morphologic normal prostate tissue of adult men investigated by energy dispersive X-ray fluorescent analysis. X-Ray Spectrom 40: 464-469.
  18. Zaichick V, Nosenko S, Moskvina I (2012) The effect of age on 12 chemical element contents in the intact prostate of adult men investigated by inductively coupled plasma atomic emission spectrometry. Biol Trace Elem Res 147: 49-58.[crossref]
  19. Zaichick S, Zaichick V, Nosenko S, Moskvina I (2012) Mass Fractions of 52 Trace Elements and Zinc Trace Element Content Ratios in Intact Human Prostates Investigated by Inductively Coupled Plasma Mass Spectrometry. Biol Trace Elem Res 149: 171-183.
  20. Zaichick V, Zaichick S (2014) Age-related histological and zinc content changes in adult nonhyperplastic prostate glands. Age (Dordr) 36: 167-181.[crossref]
  21. Zaichick V, Zaichick S2 (2014) INAA application in the assessment of chemical element mass fractions in adult and geriatric prostate glands. Appl Radiat Isot 90: 62-73.[crossref]
  22. Zaichick V, Zaichick S (2014) Determination of trace elements in adults and geriatric prostate combining neutron activation with inductively coupled plasma atomic emission spectrometry. Open Journal of Biochemistry 1: 16-33.
  23. Zaichick V, Zaichick S (2014) Use of INAA and ICP-MS for the assessment of trace element mass fractions in adult and geriatric prostate. J Radioanal Nucl Chem 301: 383-397.
  24. Zaichick V (2015) The Variation with Age of 67 Macro- and Microelement Contents in Nonhyperplastic Prostate Glands of Adult and Elderly Males Investigated by Nuclear Analytical and Related Methods. Biol Trace Elem Res 168: 44-60.[crossref]
  25. Zaichick V, Zaichick S (2015) Dietary intake of minerals and prostate cancer: insights into problem based on the chemical element contents in the prostate gland. J Aging Res Clin Practice 4: 164-171.
  26. Zaichick V, Zaichick S (2015) Global contamination from uranium: insights into problem based on the uranium content in the human prostate gland. J Environ Health Sci 1: 1-5.
  27. Zaichick V, Zaichick S (2016) Variations in concentration and distribution of several androgen-dependent and -independent trace elements in nonhyperplastic prostate gland tissue throughout adulthood. J Androl Gynaecol 4: 1-10.
  28. Zaichick V, Zaichick S (2016) Age-related changes in concentration and histological distribution of Br, Ca, Cl, K, Mg, Mn, and Na in nonhyperplastic prostate of adults. European Journal of Biology and Medical Science Research 4: 31-48.
  29. Zaichick V, Zaichick S (2016) Variations in concentration and histological distribution of Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn in nonhyperplastic prostate gland throughout adulthood. Jacobs Journal of Cell and Molecular Biology 2: 1-16.
  30. Zaichick V (2006) Medical elementology as a new scientific discipline. J Radioanal Nucl Chem 269: 303-309.
  31. Schwartz MK (1975) Role of trace elements in cancer. Cancer Res 35: 3481-3487[crossref]
  32. Kubo H, Hashimoto S, Ishibashi A, Chiba R, Yokota H, et al. (1976) Simultaneous determinations of Fe, Cu, Zn, and Br concentrations in human tissue sections. Medical Physics 3: 204-209.
  33. Forssén A (1972) Inorganic elements in the human body. I. Occurrence of Ba, Br, Ca, Cd, Cs, Cu, K, Mn, Ni, Sn, Sr, Y and Zn in the human body. Ann Med Exp Biol Fenn 50: 99-162.[crossref]
  34. Holm W, Schneider HJ, Anke M (1971) [Mineral content of the ejaculate and its relationship to larger amounts and trace elements in the prostate, seminal vesicles, epididymis and testis]. Arch Exp Veterinarmed 25: 811-815.[crossref]
  35. Tohno S, Kobayashi M, Shimizu H, Tohno Y, Suwannahoy P, et al. (2009) Age-related changes of the concentrations of select elements in the prostates of Japanese. Biol Trace Elem Res 127: 211-227.[crossref]
  36. Leitão RG, Palumbo A, Souza PAVR, Pereira GR, Canellas CGL, et al. (2014) Elemental concentration analysis in prostate tissues using total reflection X-ray fluorescence. Radiation Physics and Chemistry 95: 62-64
  37. Marczyńska A, Kulpa J, Leńko J (1983) The concentration of zinc in relation to fundamental elements in the diseased human prostate. Int Urol Nephrol 15: 257-265.[crossref]
  38. Schneider H-J, Anke M, Holm W (1970) The inorganic components of testicle, epididymis, seminal vesicle, prostate and ejaculate of young men. Int Urol Nephrol 2: 419-427.
  39. Banas A, Kwiatek WM, Zajac W (2001) Trace element analysis of tissue section by means of synchrotron radiation: the use of GNUPLOT for SPIXE spectra analysis. Journal of Alloys and Compounds 328: 135-138.
  40. Soman SD, Joseph KT, Raut SJ, Mulay GD, Parameswaran M, et al. (1970) Studies of major and trace element content in human tissues. Health Phys 19: 641-656.
  41. Guntupalli JNR, Padala S, Gummuluri AVRM, Muktineni RK, Byreddy SR, Sreerama L et al. (2007) Trace elemental analysis of normal, benign hypertrophic and cancerous tissues of the prostate gland using the particle-induced X-ray emission technique. Eur J Cancer Prev 16: 108-115.
  42. Leitão RG, Palumbo AJ, Correia R C, Souza PAVR, Canellas CGL, Anjos M J et al. (2009) Elemental concentration analysis in Benign Prostatic Hyperplasia tissue cultures by SR-TXRF. Brazilian Synchrotron Light Laboratory, Activity Report1-2.
  43. Kwiatek WM, Banas A, Gajda M, Galka M, Pawlicki B, et al. (2005) Cancerous tissues analyzed by SRIXE. Journal of Alloys and Compounds 401: 173-177.
  44. Picurelli L, Olcina PV, Roig MD, Ferrer J (1991) [Determination of Fe, Mg, Cu, and Zn in normal and pathological prostatic tissue]. Actas Urol Esp 15: 344-350.[crossref]
  45. Györkey F, Min KW, Huff JA, Györkey P (1967) Zinc and magnesium in human prostate gland: normal, hyperplastic, and neoplastic. Cancer Res 27: 1348-1353.[crossref]
  46. Hienzsch E, Schneider H-J, Anke M (1970) Vergleichende Untersuchungen zum Mengen- und Spurenelementgehalt der normalen Prostata, des Prostataadenoms und des Prostatakarzinoms. Zeitschrift für Urologie und Nephrologie 63: 543-546.
  47. Yaman M, Atici D, Bakirdere S, Akdeniz I (2005) Comparison of trace metal concentrations in malign and benign human prostate. J Med Chem 48: 630-634.[crossref]
  48. Zaichick V, Zaichick S (2015) Differences and relationships between morphometric parameters and zinc content in nonhyperplastic and hyperplastic prostate glands. British Journal of Medicine and Medical Research 8: 692-706.
  49. Zaichick V, Zaichick S (2016) Trace element contents in adenocarcinoma of human prostate investigated by energy dispersive X-ray fluorescent analysis. Journal of Adenocarcinoma 1: 1-7.
  50. Zaichick V, Zaichick S (2016) The Bromine, Calcium, Potassium, Magnesium, Manganese, and Sodium Contents in Adenocarcinoma of Human Prostate Gland. J Hematology and Oncology Research 2: 1-12.
  51. Zaichick V, Zaichick S (2016) Trace element contents in adenocarcinoma of the human prostate gland investigated by neutron activation analysis. Cancer Research and Oncology 1: 1-10.
  52. Zaichick V, Zaichick S (2016) Prostatic tissue levels of 43 trace elements in patients with prostate adenocarcinoma. Cancer and Clinical Oncology 5: 79-94.
  53. Zaichick V, Zaichick S (2016) Chemical elemental content / Calcium ratios in tissues of human hyperplastic prostate gland. Journal of Applied Life Sciences International 4: 1-11.
  54. Zaichick V, Zaichick S, Davydov G (2015) Differences between chemical element contents in hyperplastic and nonhyperplastic prostate glands investigated by neutron activation analysis. Biol Trace Elem Res 164: 25-35.[crossref]
  55. Zaichick V, Zaichick S (2016) Prostatic tissue level of some major and trace elements in patients with BPH. Jacobs Journal of Nephrology and Urology 3: 1-10.
  56. Zaichick V, Zaichick S (2016) Levels of 43 Trace Elements in Hyperplastic Prostate Tissues. British Journal of Medicine and Medical Research 15: 1-12.
  57. Zaichick VYe, Sviridova TV, Zaichick SV (1997) Zinc in the human prostate gland: normal, hyperplastic and cancerous. Int Urol Nephrol 29: 565-574.[crossref]
  58. Zaichick S, Zaichick V (2012) Trace elements of normal, benign hypertrophic and cancerous tissues of the human prostate gland investigated by neutron activation analysis. Appl Radiat Isot 70: 81-87
  59. Zaichick V (1997) Sampling, sample storage and preparation of biomaterials for INAA in clinical medicine, occupational and environmental health. In: Harmonization of Health-Related Environmental Measurements Using Nuclear and Isotopic Techniques. IAEA, Vienna23-133.
  60. Zaichick V, Zaichick S (1996) Instrumental effect on the contamination of biomedical samples in the course of sampling. The Journal of Analytical Chemistry 51: 1200-1205.
  61. Zaichick V, Zaichick S (1997) A search for losses of chemical elements during freeze-drying of biological materials. J Radioanal Nucl Chem 218: 249-253.
  62. Zaichick V (2004) Losses of chemical elements in biological samples under the dry aching process. Trace Elements in Medicine 5: 17-22.
  63. Zaichick V (1995) Applications of synthetic reference materials in the medical Radiological Research Centre. Fresenius J Anal Chem 352: 219-223.
  64. Korelo AM, Zaichick V (1993) Software to optimize the multielement INAA of medical and environmental samples. In: Activation Analysis in Environment Protection. Joint Institute for Nuclear Research, Dubna, Russia 326–332.
  65. Catalona WJ (1996) Clinical utility of measurements of free and total prostate-specific antigen (PSA): a review. Prostate Suppl 7: 64-69.[crossref]
  66. Genes VS (1967) Simple methods for cybernetic data treatment of diagnostic and physiological studies. Nauka, Moscow.