May 7, 2015
Hardell and Carlberg (2015) recently reported that brain tumor rates have been increasing in Sweden based upon the Swedish National Inpatient Registry data.
What about brain tumor rates in the United States?
Using national tumor registry data, a recent study found that the overall incidence of meningioma, the most common non-malignant brain tumor, has significantly increased in the United States in recent years (Dolecek et al., 2015). The age-adjusted incidence rate for meningioma significantly increased from about 6.3 per 100,000 in 2004 to about 7.8 per 100,000 in 2009. Brain tumor incidence increased for all age groups except youth (0-19 years of age).
The incidence of glioma, the most common malignant brain tumor, has also been increasing in recent years in the United States, although not across-the-board.
The National Cancer Institute reported that glioma incidence in the frontal lobe increased among young adults 20-29 years of age (Inskip et al., 2010
). The incidence of glioblastoma multiforme, a highly cancerous glioma, increased in the frontal and temporal lobes, and in the cerebellum among adults of all ages in the U.S. (Zada et al., 2012
Risk of meningioma from cell phone and cordless phone use
A new study by Carlberg and Hardell (2015)
adds to the growing body of evidence that heavy use of wireless phones (i.e., cell phones and cordless phones) is associated with increased risk of meningioma in Sweden. Heavy cordless phone users (defined as more than 1,436 hours of lifetime use) had a 1.7-fold greater risk of meningioma (OR = 1.7; 95% CI = 1.3-2.2). The heaviest cordless phone users (defined as more than 3,358 hours of lifetime use) had a two-fold greater risk of meningioma (OR = 2.0; 95% CI = 1.4 – 2.8). The heaviest cell phone users had a 1.5-fold greater risk of meningioma (OR = 1.5, 95% CI = 0.99 – 2.1).
Two earlier case-control studies conducted in other nations have found significant evidence of increased risk for meningioma among heavy cell phone users:
(1) In France, Coureau et al. (2014)
found a two and a half-fold greater risk of meningioma for heavy cell phone users (defined as 896 or more hours of lifetime use) (OR = 2.57; 95% CI = 1.02 to 6.44).
(2) In Australia, Canada, France, Israel and New Zealand, Cardis et al. (2011) found a two-fold greater risk of meningioma for heavy cell phone users (defined as 3,124 or more hours of lifetime use) (OR = 2.01; 95% CI = 1.03 to 2.93).
The two prior studies did not assess cordless phone use so it’s likely they underestimate the meningioma risk from cell phone use.
Thus, we now have three independent, case-control studies which find that wireless phone use is a risk factor for meningioma.
Risk of glioma from cell phone and cordless phone use
Three independent, case-control studies have found that long-term use of cell phones increases risk for glioma (Interphone Study Group, 2010; Hardell et al, 2013; Coureau et al, 2014). The only research to examine cordless phone use also found increased glioma risk with long-term use (Hardell et al, 2013). These studies include data from 13 nations: Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden and the UK. After ten years of wireless phone use (i.e., cell phone plus cordless phone use), the risk of glioma doubles and after 25 years, the risk triples (Hardell et al, 2013).
Although the U.S. does not conduct research on wireless phone use and tumor risk in humans and does not participate in any of the international studies, there is no reason to believe that Americans are immune to these potential effects of wireless phone use.
In sum, the peer-reviewed research on brain tumor risk and wireless phone use strongly suggests that we should exercise precaution and keep cell phones and cordless phones away from our heads. Moreover, the research calls into question the adequacy of national standards and international guidelines that limit our exposure to radiation from wireless phones.
Aug 5, 2015
Cancer registries are developed to collect data on malignant tumors and often do not collect data on non-malignant (sometimes called benign) tumors. Since about half of primary brain tumors are non-malignant, these tumors are may not be monitored by public health surveillance systems (e.g., Canada).
The U.S has a Central Brain Tumor Registry
(CBTRUS): “a resource for gathering and disseminating current epidemiologic data on all primary brain tumors, benign and malignant
, for the purposes of accurately describing their incidence and survival patterns, evaluating diagnosis and treatment, facilitating etiologic studies, establishing awareness of the disease, and ultimately, for the prevention of all brain tumors.” However, “CBTRUS makes no representations or warranties, and gives no other assurances or guarantees, express or implied, with respect to the accuracy or completeness of the data presented.”
There is a good reason for the disclaimer on the CBTRUS home page. Tumor registries are useful in monitoring disease incidence only to the extent that all procedures are well implemented. Registries are highly dependent upon reporting agencies (e.g., hospitals) to do an accurate and complete job in reporting tumors to the registry.
Registry data typically suffer from various problems:
“Users must be aware of diverse issues that influence collection and interpretation of cancer registry data, such as multiple cancer diagnoses, duplicate reports, reporting delays, misclassification of race/ethnicity, and pitfalls in estimations of cancer incidence rates.” (Izqierdo, JN, Schoenbach, VJ. The potential and limitations of data from population-based state cancer registries. AmJ Public Health. 2000;90:695-698. URL: http://1.usa.gov/1IHO8FM)
These shortcomings of cancer registries are not just hypothetical. For example, Hardell and Carlberg (2015)
recently reported that brain cancer rates have been increasing in Sweden based upon the Swedish National Inpatient Registry but not according to the Swedish Cancer Registry. Based upon their results they “postulate(d) that a large part of brain tumours of unknown type are never reported to the Cancer Register … We conclude that the Swedish Cancer Register is not reliable …”