An article published in the Journal of Environmental and Public Health in late April studied the incidence of brain tumors in the United Kingdom (UK) from 1995 to 2015. The group looked to study trends of malignant tumor occurrences over time. The group used the United Kingdom’s Office of National Statistics data covering over 81,000 malignant primary brain tumors (ICD10 coded) diagnosed between that span of years including blastoma, carcinoma, sarcoma, and gliomas of differing sub-groups. They calculated incidence rates from that data. Their findings resulted in a statistically significant incidence rate trend for Glioblastoma Multiforme (GBM). They found that within data showing a decreasing incidence of lower grade tumors, GBM’s annual case numbers are rising dramatically over time after age-standardization.
Glioblastoma Multiforme is a fast-growing type of brain tumor that forms from glial cells. The cancer is also referred to as a grade IV astrocytoma because glial cells can be astrocytes and oligodendrocytes which surround neurons to provide support and protection. GBM is invasive and quickly spreads to brain tissue in close proximity. The etiology of GBMs is not well understood but scientists and providers believe it can develop de novo or evolve from lower grade astrocytomas or other gliomas. Prognosis is not very good with a median survival rate of 15 months.
The study done in the UK provides a good longitudinal look at brain tumor incidence over time and determined that the increases in GBMs had to be related to environmental changes or lifestyle factors rather than increased promotion of lower-grade tumors, chance, or improvement in diagnostic measures.
Multiple web articles have appeared as a result of this publication and one of the authors’ comments that cell phones seem a likely cause, however the web articles could not be substantiated, nor the authors' comments. This study is not about cell phone radio frequency and does not associate their use with brain tumors. While nothing can really be ruled out as a causative agent, many studies have not shown a link between brain tumor development and cell phone use, though the potential for damage is certainly there. The steady rise in GBM rates was reported to be present from 2004 to 2015 and that most secondary GBMs were found in younger middle-aged people, whereas most primary GBMs were found in individuals over 60 years of age. Many of these tumors are focused on the frontal and temporal lobes. The authors discuss and reject the theory that improved diagnosis due to better imaging and categorical tools could be an explanation for the trend. They did speculate about potential factors that could be causing the increased rates including broader use of computed tomography (CT) scans, atmospheric bomb testing fallout and the ingestion/inhalation of radionuclides for the older generation of the study, and cell phone use. They reported that the most support pointed to the increased broad use of CT; radiation exposure builds upon itself; radiation exposure consequences persist throughout life regardless of age at exposure. One study referenced from JAMA in 2011 showed that brain glucose metabolism changed after exposure to cell phone radiofrequency for 50 minutes. The effects of brain glucose metabolism and formation of GBM were not discussed by the authors, however there is literature to suggest that cancers, including gliomas, may have a mitochondrial metabolic driver dysfunction due to genetic expression changes.
This study helped to showcase the rising rates of GBM incidence in the UK and that this could be caused by environmental or lifestyle factors within individual control. There is no evidence in this work that suggests that cell phone use is the single causative agent of this trend. There are a multitude of environmental exposure factors that are hard to measure, quantify, and control for when evaluating cancer formation and development.