Trace elements in hair or fingernail and gastroesophageal cancers: results from a population-based case-control study

A critical review on the relevance, essentiality, and analytical techniques of trace elements in human cancer

Trace elements (TEs) are indispensable nutritional elements, playing a pivotal role in maintaining human health and serving as essential cofactors for numerous enzymes that facilitate crucial biological processes. The dysregulation (excess or deficiency) of TEs can affect the proper functioning of various organs and lead to diseases like cancer. However, the current research findings remain contentious, and the association between TE variations and cancer remains elusive. This article reviews the recent advances in the quantitative detection of TEs in tumor research to fully understand the important role of TEs in disease diagnosis and prognosis. The changes in the levels of various elements (such as Cu, Zn, Fe, Se, Ca, etc.) are analyzed and summarized from five systems of the human body, including the digestive system, urinary system, reproductive system, endocrine system, and respiratory system. By analyzing the relevant findings in diverse biological samples, we systematically investigate the disruption of TEs homeostasis in cancer patients, thereby underscoring the potential of TEs as cancer biomarkers. We also present novel analytical techniques such as isotope ratio determination and bioimaging, along with advanced auxiliary tools like machine learning, for the detection of TEs in disease research. This review aims to provide a comprehensive overview of TEs variations in the main cancer types of different systems, which addresses the knowledge gap in TEs on human health, and provides proposals for future research.

Lead (Pb) in biological samples in association with cancer risk and mortality: A systematic literature review

BACKGROUND AND AIM

Lead (Pb) is a toxic heavy metal and pervasive environmental contaminant, and a class 2 A carcinogen according to the IARC classification, yet its link with cancer at several body sites remains uncertain. Here, we aimed at summarizing the scientific evidence regarding its association with cancer risk and mortality, focusing on studies that carried out Pb measurements in biological samples.

METHODS

We reviewed articles published in PubMed and EMBASE until January 2nd, 2024, that quantified the epidemiological association between Pb measured in blood, urine, nails, and other biological media, and cancer risk and mortality (overall and by cancer site/type).

RESULTS

We included 46 articles (out of 8022 screened) published in 1995-2023 and reporting on investigations conducted in fifteen countries. In terms of design, 20 were prospective, 24 were retrospective case-control studies, and 2 were cross-sectional. Pb levels were determined in blood in the majority of studies (n=28). The most consistent evidence was for the association of Pb with cancer of the gastrointestinal tract, particularly the oesophagus, stomach (RR ranging from 0.80 to 2.66), colon-rectum, and pancreas; and of the bladder and urinary tract (RR from 1.10 to 2.89). For other specific malignancies, the data were conflicting or too limited to draw reliable conclusions. Finally, increased Pb concentration in blood and urine was consistently associated with higher overall cancer incidence and mortality.

CONCLUSIONS

Lead is a widespread and highly persistent environmental pollutant associated with cancer at multiple body sites. Comprehensive primary prevention interventions aiming at reducing opportunities for Pb exposure need to be continuously promoted and implemented.

The association between trace metals in both cancerous and non-cancerous tissues with the risk of liver and gastric cancer progression in northwest China

Liver cancer and gastric cancer have extremely high morbidity and mortality rates worldwide. It is well known that an increase or decrease in trace metals may be associated with the formation and development of a variety of diseases, including cancer. Therefore, this study aimed to evaluate the contents of aluminium (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), selenium (Se), and zinc (Zn) in cancerous liver and gastric tissues, compared to adjacent healthy tissues, and to investigate the relationship between trace metals and cancer progression. During surgery, multiple samples were taken from the cancerous and adjacent healthy tissues of patients with liver and gastric cancer, and trace metal levels within these samples were analysed using inductively coupled plasma mass spectrometry (ICP-MS). We found that concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn in tissues from patients with liver cancer were significantly lower than those in healthy controls (P < 0.05). Similarly, patients with gastric cancer also showed lower levels of Cd, Co, Cr, Mn, Ni, and Zn-but higher levels of Cu and Se-compared to the controls (P < 0.05). In addition, patients with liver and gastric cancers who had poorly differentiated tumours and positive lymph node metastases showed lower levels of trace metals (P < 0.05), although no significant changes in their concentrations were observed to correlate with sex, age, or body mass index (BMI). Logistic regression, principal component analysis (PCA), Bayesian kernel regression (BKMR), weighted quantile sum (WQS) regression, and quantile-based g computing (qgcomp) models were used to analyse the relationships between trace metal concentrations in liver and gastric cancer tissues and the progression of these cancers. We found that single or mixed trace metal levels were negatively associated with poor differentiation and lymph node metastasis in both liver and gastric cancer, and the posterior inclusion probability (PIP) of each metal showed that Cd contributed the most to poor differentiation and lymph node metastasis in both liver and gastric cancer (all PIP = 1.000). These data help to clarify the relationship between changes in trace metal levels in cancerous liver and gastric tissues and the progression of these cancers. Further research is warranted, however, to fully elucidate the mechanisms and causations underlying these findings.