Background
Exposure to radiofrequency electromagnetic fields (RF-EMF; frequencies ranging from 100 kHz to 300 GHz) is ubiquitous in modern society. Concerns regarding potential health effects persist. The World Health Organization highlighted cancer as a primary concern associated with RF-EMF exposure. Numerous systematic reviews (SR) have been published on this topic, sometimes with conflicting results.  
Objectives 
This umbrella review aims to synthesize the available evidence on the relationship between near-field RF-EMF exposure - primarily from mobile phones - and neoplastic diseases.
Methods
We followed our published protocol to retrieve SRs and meta-analyses of human observational studies examining the association between near-field RF-EMF exposure and cancer. Searches were conducted in MEDLINE, Web of Science Core Collection, EMF-Portal, and Epistemonikos from database inception to 15 May 2024. Eligibility criteria were structured using the Population, Exposure, Comparator, Outcome, Study type (PECOS) framework, and the process adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Methodological quality and risk of bias were assessed using A Measurement Tool to Assess Systematic Reviews, version 2 (AMSTAR 2), and a qualitative synthesis was performed using standardized forms.
Results 
The 33 SRs synthesized in this analysis investigated outcomes such as intracranial tumors (glioma, meningioma, acoustic neuroma), salivary gland tumors, and other malignancies. Overall, the quality of evidence was low. Using AMSTAR 2, all included SRs were rated as critically low quality. Major additional issues included overlap of primary studies, unjustified exclusion of data, misreporting, use of inappropriate data extraction methods and pooling of heterogeneous outcomes.
Conclusions/Implications
The systematic reviews assessed within the eligibility period demonstrated poorly defined scopes and inconsistent reporting. While the AMSTAR 2 tool effectively evaluated the transparency of the systematic review process, it did not fully capture all the methodological shortcomings present in the reviews. These findings underscore the urgent need for improved training in systematic review methodology, particularly for observational epidemiology, to enhance the reliability of future research.
The inconsistent quality, incomplete reporting, and methodological flaws observed in the systematic reviews—covering studies up to May 2024—compromised the ability to draw reliable conclusions. As per our protocol, an updated search will be conducted prior to publication to ensure the inclusion of the most recent evidence. For this topic, well-designed, transparent, and comprehensive systematic reviews are more suitable than umbrella reviews, which risk exacerbating existing flaws rather than mitigating them.
Funding 
NextGEM Project- Funded by the European Union.