Cancer is a multi-stage disease that involves the initiation, promotion, and progression of cells, driven by an imbalance between growth and death. An individual with breast cancer develops malignant tumors that originate from the cells of the breast. Malignant cells make up these cancerous growths, which are capable of invading surrounding tissues or spreading throughout the body. While the disease predominantly affects women, men can also be affected [1-4]. Global Impact: Each year, more than 1,000,000 women worldwide receive a diagnosis of breast cancer [5]. Breast cancer is the most frequently diagnosed form of cancer in women and is one of the leading causes of cancer-related mortality [6]. The disease claims the lives of more than five hundred thousand women annually. Tumor markers, which are substances detected in the bloodstream of people with cancerous conditions, serve a vital role in various aspects of cancer management, including diagnosis (such as distinguishing different types of cancer), early identification, prognosis assessment, monitoring for disease recurrence, and evaluating treatment effectiveness [7]. Damage to DNA induced by reactive oxygen species (ROS) encompasses both double and single strand breaks, modifications to deoxyribose, pyrimidine, and purine, DNA-protein crosslinks, and intrastrand adducts. This DNA damage can lead to the disruption or activation of gene transcription, replication mistakes, the triggering of signaling pathways, and chromosomal instability - all of which are associated with the development of cancer. The interplay between the free radicals superoxide (O2•−) and nitric oxide (•NO) results in the formation of peroxynitrite (ONOO−), a highly reactive compound that causes both nitrosative and oxidative harm to DNA [8,9].

Breast tumors typically thrive in an intensely pro-oxidative environment, given the rich adipose tissue surrounding the mammary gland. Consequently, reactive oxygen species (ROS) rapidly act on lipids in the vicinity, yielding various active metabolites that can modulate a wide range of cellular processes. Noteworthy examples of these metabolites arising from lipid peroxidation, such as low-molecular-weight aldehydes (e.g., Malondialdehyde, 8-F2-isoprostanes, and 4-hydroxynonenal), have been proposed as potential markers of oxidative status in breast cancer patients [10]. Several risk factors for breast cancer that can be modified have been recognized, such as radiation exposure, alcohol use, excess body weight, hormonal influences, and inadequate physical activity. Lifestyle factors, considered among the most impactful determinants, have become increasingly emphasized. Emerging evidence underscores the crucial role of diet, a key component of a healthy lifestyle, in breast cancer development. Since diet is a modifiable risk factor estimated to contribute to around 35% of all cancer cases, it is increasingly crucial to understand and manage the role of dietary factors in the development of cancer [11]. Previous research on the dietary factors influencing breast cancer development has considered various aspects, including nutrient intake, dietary patterns, and individual food groups. For instance, high consumption of processed meat, alcohol, and animal fats, coupled with low intake of dietary fiber, fruits, and vegetables, may be linked to an increased risk of breast cancer [12]. In biochemistry, lipids are characterized by glycerol backbones and three fatty acid chains joined by ester bonds [13]. Breast cancer risk has consistently been linked to total dietary fat intake in case-control studies [1]. According to a meta-analysis, women who consume more total fat have a 13% lower risk of breast cancer compared to those who consume less total fat. Increasing chylomicrons in the intestine can result in elevated free fatty acids (FFAs). As a result, these FFA can be directed to mitochondria for β-oxidation. Oxidative stress is caused by the cytochrome c oxidase component in the electron transport chain, which increases electron flow leading to increased reactive oxygen species [14]. Obese people often have high levels of free fatty acids (FFAs), and this is particularly concerning for breast cancer patients. That's because breast cancer cells tend to have a lot of receptors for a hormone called leptin. Leptin can influence some important cancer-related processes, like programmed cell death (apoptosis), inflammation, and how sensitive the cells are to estrogen. Another hormone, called adiponectin, helps tissues respond better to insulin. But obese people usually have low levels of adiponectin, which can lead to high insulin levels. Too much insulin can actually boost cell division and block apoptosis - that's the last thing you want for cancer patients. So the hormonal imbalances that come with obesity seem to create an environment that promotes tumor growth, spread, and ultimately, a higher risk of dying from breast cancer [15]. On top of that, some nutrients like zinc may also play a role. Zinc is important for regulating cell growth and death. Zinc and another mineral, selenium, also have immune-boosting and antioxidant effects, which could be helpful against cancer [16,17].

In this study, we hypothesized that the levels of cholesterol and calcium, which can serve as indicators for breast cancer, are elevated in individuals with breast cancer. To test this hypothesis, we conducted a comparative analysis of the baseline concentrations of cholesterol, high-density lipoprotein cholesterol, calcium, and zinc in both breast cancer patients and individuals without breast cancer. The aim of this study was to explore the relationships between the occurrence of breast cancer and the levels of cholesterol, high-density lipoprotein cholesterol, calcium, and zinc.

Methods

Using a colorimetric method, the plasma levels of cholesterol, high-density lipoprotein cholesterol, calcium, and zinc in the serum were measured in a cohort of 30 breast cancer patients and 30 healthy individuals. All the results were then subjected to statistical analysis

Subjects

Cholesterol, high-density lipoprotein cholesterol, calcium, and zinc levels in the serum were assessed in two groups: 30 individuals without health issues and 30 breast cancer patients. The mean age of the control group (47.93±3.05) and the patient group (46.73±3.54) was randomly selected from breast cancer patients between October and March 2024. Comprehensive data regarding the clinical history of each participant, including age, prevalent illnesses, duration of the disease, daily dietary habits, and occupation, was obtained.

Strategies

All participants underwent a comprehensive clinical history review, physical examination, and specific breast cancer assessments. The researchers took 5 ml of blood from a vein in both the patient group and the control group. Then they spun the blood samples in a centrifuge machine made by Gallen in Germany. They spun it at 3000 revolutions per minute (RPM) for 10 minutes to separate out the liquid part of the blood, called the serum. After that, they stored the serum samples in sealed plastic tubes and stuck them in a freezer set to -20°C (that's about -4°F). They kept the samples frozen until they were ready to do some more analysis on them later. Cholesterol, high-density lipoprotein cholesterol, calcium, and zinc levels in the serum were determined using the spectrophotometric method at 420 nm and 430 nm, with a Shimadzu UV-visible spectrophotometry model U.V-160. The final concentrations are expressed in pg/ml.

Measurable examination

The data are expressed as the mean ± standard error of the mean (SEM). Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS), and significant differences between the control and patient groups were assessed using Student's t-test. A probability threshold of (P < 0.05) was deemed indicative of statistical significance.

The serum concentrations of cholesterol and calcium were notably higher in individuals with breast cancer compared to the control subjects (P < 0.05). In contrast, the levels of high-density lipoprotein cholesterol and zinc in the blood were significantly lower in the patient group (P < 0.05) than in the control group. Details regarding clinical characteristics, including age and others, are summarized in Table 1.

Table 1. General Characteristics of the Healthy Controls and Breast Cancer Patients.

The results showed that the serum levels of cholesterol and calcium were significantly higher in breast cancer patients compared to the controls (p < 0.05), as depicted in Figures 1a and 1b, respectively. On the other hand, the serum levels of high-density lipoprotein cholesterol and zinc were significantly lower in breast cancer patients than in the controls (p < 0.05), as shown in Figures 1c and 1d.

Figure 1. a) Cholesterol levels, b) Calcium levels, c) Zinc levels, and d) HDL cholesterol levels, in healthy controls and patients (p<0.05).

The results of our study indicate an increase in the levels of cholesterol and calcium in breast cancer patients compared to the control group. This is consistent with previous research and suggests heightened lipid peroxidation in individuals with breast cancer [18]. Notably, our findings provide evidence suggesting a positive association between relatively high levels of calcium in benign breast tissue and an increased risk of developing breast cancer at a later stage. Although this association may be incidental, it is possible that benign breast tissue accumulating higher concentrations of the essential trace element calcium might be prone to developing breast cancer, given the crucial role of an adequate supply of zinc in maintaining breast health [19].

Zinc is an essential micronutrient with multifaceted functions in mammalian cells, playing crucial structural and regulatory roles [20]. Acting as a cofactor, zinc interacts with zinc-binding motifs, such as "zinc finger" domains, and is involved in the functioning of numerous enzymes [1]. Additionally, zinc participates in the binding of transcription factors to DNA and the modulation of membrane receptor, transporter, and channel activity [21]. Therefore, a significant depletion of zinc can have profound effects on cellular physiology. Indeed, previous studies have demonstrated that cellular zinc deficiency, induced by either intermediate zinc chelators or permeabilization of zinc-deficient cells, can result in cellular dysfunction and the induction of apoptosis across various cell types. Beyond its physiological roles, recent research has highlighted the involvement of zinc in the regulation of cell proliferation and cell death [22].

Breast calcifications, characterized by deposits of calcium within breast tissue, manifest on mammograms as white patches or spots. The occurrence of breast calcifications on mammograms is common, with their frequency increasing after the age of fifty. While breast calcifications are typically benign, certain patterns, such as irregular clusters, may signify breast cancer or precancerous changes in breast tissue [23]. These calcifications are visible as either large or small formations on mammograms. Large calcifications, appearing as circular dots or lines, are non-cancerous in nearly all cases and generally do not necessitate further testing or follow-up. Small calcifications, resembling fine white spots resembling grains or salt, are usually noncancerous, but specific patterns can indicate early signs of cancer [24].

Cholesterol plays a significant role in the composition of living cell membranes, contributing to the formation of essential substances in the body, including hormones like testosterone, estrogen, and progesterone. Additionally, it is vital in bile production in the liver stored in the gallbladder, among other functions. However, an elevation in cholesterol or any issues in its production can lead to severe and challenging problems affecting human health and life. Disorders related to cholesterol can contribute to various diseases directly linked to breast cancer [25].

In this study, we found that the serum levels of cholesterol and calcium are elevated in breast cancer patients compared to healthy controls.

The presence of fats in the diet has been found to have a detrimental impact on breast cancer, increasing the risk of its development and reducing survival rates. Implementing dietary control emerges as a crucial intervention to mitigate the incidence and mortality associated with breast cancer globally. The findings of this study provide support for a definitive connection between family history and the risk of breast cancer, whereas no such association was observed with smoking or living conditions. Moreover, the results indicate that patients with breast cancer exhibited elevated levels of oxidative/nitrosative stress markers.

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