A review of existing research on mercury levels and colorectal cancer found no significant link between mercury levels and CRC risk, underscoring the complexity of environmental toxins in cancer etiology and the need for further research on influencing factors.
Abstract
Background
This study examines how mercury (Hg) levels may be linked to colorectal cancer (CRC) by reviewing and analyzing existing research. It is important to understand this connection because mercury may cause cancer.
Methods
We searched PubMed, Scopus, and Web of Science for studies published up to January 2026. We included observational studies evaluating mercury levels in patients with CRC compared with healthy controls or non-cancerous colorectal tissue, as well as studies assessing the association between mercury exposure and colorectal cancer. We analyzed the data using a random-effects model. Mercury levels were measured in subgroups within both the case and control groups to address differences in measurement methods. We assessed the quality of the included studies using the Newcastle-Ottawa Scale. All data were analyzed with STATA version 17.
Results
This meta-analysis reviewed 8 studies selected from 1,099 database records. Four studies with 773 participants (355 cases and 418 controls) found no significant difference in mercury levels between people with colorectal cancer and healthy controls (SMD: 0.16 [-0.22, 0.54]; p = 0.42; I²: 82.25%). Subgroup analysis showed differences depending on study design, average age, percentage of male participants, and risk of bias score. Meta-regression found that participant age affected the results, while other factors did not. In two studies with 71 participants, there was also no significant difference in mercury levels between colorectal and healthy tissues in patients with colorectal cancer (SMD: -0.24 [-1.11, 0.64]; p = 0.60; I²: 76.68%), despite high variability across studies.
Conclusion
Our review found no significant link between mercury levels and CRC risk, underscoring the complexity of environmental toxins in cancer etiology and the need for further research on influencing factors.
This study demonstrates a significant positive association between blood lead levels and the risk of HU and no significant association is found between blood levels of cadmium, manganese, and mercury and the risk of HU.
Yanxia Gan, Xi Yu, Puhui Zhou· Joint Bone Spine· 0 citations
Background/Objectives: Gastric cancer is a major global health challenge with multifactorial aetiology. Vitamin D has been investigated for a potential role in gastric carcinogenesis, but evidence remains heterogeneous. This systematic review aimed to synthesise evidence on serum 25(OH)D, dietary vitamin D intake and VDR polymorphisms in relation to gastric cancer in adults and children. Methods: A systematic search following PRISMA 2020 standards was conducted in PubMed, Web of Science, Scopus and Lens.org for studies published from January 2007 to January 2026. Observational studies evaluating vitamin D exposure or VDR polymorphisms in relation to gastric cancer were eligible. Risk of bias was assessed using established instruments. Where comparable data were available, random-effects meta-analyses were performed, with REML estimation and Knapp–Hartung adjustment. Results: Twenty-four studies met the inclusion criteria, and no eligible paediatric studies were identified. Four studies evaluating serum 25(OH)D showed a non-significant tendency towards lower concentrations in gastric cancer patients (MD = −8.82 ng/mL, 95% CI −18.15 to 0.51). Five studies evaluating dietary vitamin D showed no significant association with gastric cancer risk (OR = 0.87, 95% CI 0.47–1.60). Five studies evaluating the VDR FokI polymorphism under the dominant model demonstrated increased gastric cancer susceptibility among variant carriers (OR = 1.44, 95% CI 1.03–2.01). Conclusions: Associations between vitamin D and gastric cancer varied by exposure type. Serum 25(OH)D and dietary intake showed no significant pooled associations, whereas VDR FokI was associated with increased gastric cancer susceptibility. The absence of paediatric evidence highlights an important knowledge gap.
Roxana Pântea, L. Meliț· Medical Science· 0 citations
Background Esophageal cancer remains a leading cause of cancer-related mortality worldwide, yet the association between coffee consumption—a ubiquitous dietary exposure—and its risk remains inconclusive. This meta-analysis systematically evaluates the association between coffee consumption and esophageal cancer risk, aiming to quantify the overall effect and explore potential heterogeneity. Methods A systematic search of PubMed, Cochrane Library, Embase, and Web of Science was conducted up to January 2026 for studies comparing coffee intake between esophageal cancer patients and healthy controls. Two reviewers independently extracted data. Pooled odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using random- or fixed-effects models. Heterogeneity was assessed using the I2 statistic. Certainty of evidence was rated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Results Across 22 included studies encompassing 1,775,988 participants (7,124 cases), neither cohort nor case-control studies demonstrated a significant association between coffee consumption and esophageal cancer risk. The pooled HR from cohort studies was 0.87 (95% CI: 0.74–1.03; I2=24.2%), while the pooled OR from case-control studies was 1.02 (95% CI: 0.77–1.35; I2=66.7%). Conclusions This meta-analysis found no statistically significant association between coffee consumption and esophageal cancer risk. The available evidence, of low certainty, does not support coffee as a major risk factor. Exploratory analyses on beverage temperature are inconclusive and require confirmation in prospective studies with standardized exposure assessment. This review was registered in PROSPERO (CRD42024562527).
The findings suggest that lead exhibits threshold-free linear toxicity, while manganese may have a protective effect, supporting preventive strategies for environmentally induced hypertension.
Yunzhen Lei, J. Diao, Ming Xu et al.· Ecotoxicology and Environmen...· 0 citations
BACKGROUND
The association between periodontitis and breast cancer (BC) risk has been reported, but with considerable variability in effect estimates across studies. This meta-epidemiological study aimed to systematically evaluate how methodological characteristics of primary studies influence these reported effect estimates.
METHODS
Cohort and case-control studies were searched in electronic databases up to February 2025. Study quality was assessed using the Newcastle-Ottawa Scale. Meta-analyses were conducted to estimate risk measures (relative risk [RR] and 95% confidence intervals [CI]). Meta-regression and subgroup analyses were performed to investigate potential variability in effect estimates.
RESULTS
Among the 19 included studies, although the overall pooled estimate indicated a 19% higher risk of BC in women with periodontitis compared with those without periodontitis (RR = 1.19; 95%CI, 1.05-1.34), meta-epidemiological analyses showed attenuated estimates in prospective vs. case-control studies (RR = 1.05 vs. 1.54), high- vs. moderate-quality studies (RR = 1.09 vs. 2.10), and adjusted vs. unadjusted analyses (RR = 1.07 vs. 1.48) (p < 0.05).
CONCLUSION
Although a small association between periodontitis and BC risk was observed, its magnitude appears to be overestimated in lower-quality, case-control, and inadequately adjusted studies. These findings underscore the importance of methodological rigor in the interpretation of the evidence.
PLAIN LANGUAGE SUMMARY
This meta-epidemiological study, based on a systematic and rigorous literature search, confirmed a modest association between periodontitis and increased breast cancer risk. The strength of this association appears to be inflated by methodological limitations in the primary studies, particularly in case-control designs and in studies with limited adjustment for confounding factors. These findings emphasize the need for high-quality prospective studies to more accurately characterize this relationship.
Rhayssa Kuhn Peitoxo, Catiusse C. Del' Agnese, M. C. Comassetto et al.· The Journal of Periodontolog...· 0 citations
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