Prostate cancer (PCa) continues to be the most frequently diagnosed neoplasm and the third leading cause of cancer-related mortality in men [1,2]. Increasing evidence has indicated that oxidative stress is associated with aging and severe age-related degenerative diseases, including cancer [3], [4], [5].

Although the causes of the high incidence of prostate cancer are poorly understood, epidemiological, experimental, and clinical studies, suggest that oxidative stress (OS) plays a major role in explaining prostate cancer development and progression [6], [7], [8], [9]. Oxidative stress is defined as the disruption of redox homeostasis between oxidants and reductants within the body due to excess production of peroxides and free radicals collectively called reactive oxygen species (ROS) [10]. This imbalance leads to oxidative DNA damage that constitutes an important mutagenic and carcinogenic factor in cancer pathogenesis [11]. Chronic increases in ROS overtime are known to induce genomic instability and neoplastic transformation, and intracellular changes in ROS levels may lead to processes that result in cell proliferation apoptosis and senescence which are associated with initiation and development of cancer including PCa [12].

To control the balance between production and removal of ROS, there are a series of protective molecules and systems globally defined as antioxidant defenses. Antioxidants which suppress such oxidative damage play important roles in aerobic organisms. They prevent free radical induced damage by preventing the formation of ROS, scavenging them or by promoting their decomposition. These include enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx), Catalase (CAT), some vitamins, and metals [13,14].

Superoxide dismutases are a class of closely related enzymes present in almost all cells and in the extracellular fluids. They catalyze the breakdown of the superoxide anion into oxygen and hydrogen peroxide [13]. Glutathione peroxidase is an enzyme containing 4 selenium cofactors that catalyze the breakdown of hydrogen peroxide to water [15]. Glutathione-S transferase (GST) is important for detoxification. Also, Glutathion (GSH) is a protector against to OS [13]. Prolidase is an expressed metallopeptidase that is uniquely required for the breakdown of proline-rich substrates including collagen [16].

In this study, we aimed to identify serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with prostate cancers and to evaluate their relationships with each other.