Cell Phone Use and Salivary Gland Tumor Risk

BACKGROUND: Prior epidemiological studies had examined the association between
cell phone use and the development of tumors in the parotid glands. However
there is no consensus about the question of whether cell phone use is
associated with increased risk of tumors in the parotid glands. We performed a
meta-analysis to evaluate the existing literature about the mean question and to
determine their statistical significance.

METHODS: Primary association studies. Papers that associated cell phone use and
parotid gland tumors development were included, with no restrictions regarding
publication date, language and place of publication. Systematic literature
search using PubMed, Scielo and Embase followed by meta-analysis.

RESULTS AND CONCLUSION: Initial screening included 37 articles and three were
included in meta-analysis. Using three independent samples including 5087
subjects from retrospective case-control studies, cell phone use seems to be
associated with greater odds (1.28, 95%- confidence interval 1.09 – 1.51) to
develop salivary gland tumor. Results should be read with caution due to the
limited number of studies available and their retrospective design.

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We further evaluated the levels of inflammatory cytokines in the saliva
produced by the parotids according to self-reported exposure to cell phone,
reporting an increase in pro-inflammatory and a decrease of anti-inflammatory
cytokine levels in the sample evaluated, suggesting a pro-inflammatory effect
of cell phones (8).

Cell phone use was associated with greater odds (increase of 28%) of presence
of tumor in the parotid glands (O.R. 1.28 95% C.I. [1.09–1.51] p = 0.0025)
(Figure 2).

Primary association studies have reported discordant results (3, 5, 10, 12, 14,
15). Possible explanations for conflicting results are differences in study
design, genetic background of sampled populations or clinical-epidemiological
sample structure. It is important to note that discordant results do not mean
that some are incorrect. Tumor manifestation is clearly a multifactorial
process whose risk factors are several. Most of the studies have not assessed
other risk factors when estimating existence of association.

This is the first systematic review followed by a meta-analysis to evaluate
that association. Here, we report usage of cell phone increase, on average, 28%
the odds of presenting parotid glands tumors.

Our results need to be read and interpreted with caution due to important
limitations that need to be addressed. Although the number of subjects compiled
is reasonably large, the number of independent samples is small (n = 3) and
results are clearly driven by two of three studies.

Conclusion

Taken together, our results provide evidence of association between cell phone
use and parotid tumor although their association presents mild effect.