Environmental Exposure to Metals, Parameters of Oxidative Stress in Blood and Prostate Cancer: Results from Two Cohorts

We studied the potential role of exposure to various metal(oid)s (As, Cd, Cr, Hg, Ni, and Pb) in prostate cancer. Two cohorts were established: the Croatian cohort, consisting of 62 cases and 30 controls, and the Serbian cohort, consisting of 41 cases and 61 controls. Blood/serum samples were collected. Levels of investigated metal(oid)s, various parameters of oxidative stress, and prostate-specific antigen (PSA) were determined in collected samples. A comparison of the measured parameters between 103 prostate cancer patients and 91 control men from both Croatian and Serbian cohorts showed significantly higher blood Hg, SOD, and GPx levels and significantly lower serum SH levels in prostate cancer patients than in controls. Correlation analyses revealed the significant relationship between certain parameters of oxidative stress and the concentrations of the measured metal(loid)s, pointing to the possible role of metal(oid)-induced oxidative stress imbalance. Furthermore, a significant inverse relationship was found between the blood Pb and the serum PSA in prostate cancer patients, but when the model was adjusted for the impacts of remaining parameters, no significant association between the serum PSA and the measured parameters was found. The results of the overall study indicate a substantial contribution of the measured metal(loid)s to the imbalance of the oxidant/antioxidant system. Although somewhat conflicting, the results of the present study point to the possible role of investigated metal(oid)s in prostate cancer, especially for Hg, since the obtained relationship was observed for both cohorts, followed by the disturbances in oxidative stress status, which were found to be correlated with Hg levels. Nevertheless, further studies in larger cohorts are warranted to explain and confirm the obtained results.

A Systematic Review of the Zinc Content of the Normal Human Prostate Gland

The prostate gland is subject to various disorders. The etiology and pathogenesis of these diseases are not well understood. Moreover, despite technological advancements, the differential diagnosis of prostate disorders has become progressively more complex and controversial. It was suggested that the Zn level in prostatic tissue plays an important role in prostatic carcinogenesis and its measurement may be useful as a cancer biomarker. These suggestions promoted more detailed studies of the Zn content in the prostatic tissue of healthy subjects. The present study evaluated by systematic analysis presents the published data for Zn content analyzed in prostatic tissue of "normal" glands. This evaluation reviewed 1885 studies, all of which were published in the years from 1921 to 2020 and were located by searching the databases PubMed, MEDLINE, Scopus, Web of Science, Elsevier-Embase, and Cochrane Library. In addition, the personal archive of the author collected from 1966 to 2020 was also used. The articles were analyzed and "median of means" and "range of means" were used to examine heterogeneity of the measured Zn content in prostates of apparently healthy men. The objective analysis was performed on data from the 105 studies, which included 3735 subjects. It was found that the range of means of prostatic Zn content reported in the literature for "normal" gland varies widely from 17 to 547 mg/kg with median of means 109 mg/kg on a wet mass basis. The Zn content depends on many factors such as analytical method, age, level of androgens, dietary Zn intake, and the prostatic region and fraction of prostate tissue being studied. Finally, because of small sample size and high data heterogeneity, we recommend other primary studies be performed.