Cell phones and brain cancer unlocking the controversy

Cell phones and brain cancer: Unlocking the controversy?Faina Linkov, PhD Assistant Professor, University of Pittsburgh Cancer Institute... Why is there a concern about cell phones and

Cell phones and brain cancer: Unlocking the controversy?

Faina Linkov, PhD

Assistant Professor, University of Pittsburgh

Cancer Institute

Why is there a concern about cell phones and breast cancer?

• Interest in the media

• New technology with rapid increase in use in

the past 10 years

• Potential exposure to Radiofrequency (RF)

“radiation”

• Limited information re: RF radiation risks

• Etiology of brain tumors largely unknown

What is brain cancer

Most brain cancers can spread through the brain tissue but rarely spread to other areas of the

body But even so-called "benign" tumors can,

as they grow, compress normal brain tissue,

causing damage that is often disabling and

sometimes fatal For this reason, doctors usually speak of "brain tumors" rather than "brain

cancers."

Glioma: Most common type of brain

cancer

Gliomas are not a specific type of cancer Glioma

is a general term for a group of tumors that start

in glial cells A number of tumors can be

considered gliomas, including glioblastoma

multiforme, astrocytomas, oligodendrogliomas, and ependymomas About 4 out of 10 of all brain tumors are gliomas Counting only malignant

tumors, about 8 out of 10 are gliomas

Brain cancer statistics

• The American Cancer Society estimates that 21,810

malignant tumors of the brain or spinal cord (11,780 in men and 10,030 in women) will be diagnosed during

2008 in the United States These numbers would likely

be much higher if benign tumors were also included

About 13,070 people (7,420 men and 5,650 women) will die from these tumors

• This would account for about 1.5% of all cancers and 2.3% of all expected cancer-related deaths in 2008

Both adults and children are included in these statistics

• Overall, the chance that a person will develop a

malignant tumor of the brain or spinal cord in his or her lifetime is less than 1% (about 1 in 150 for a man and 1

in 182 for a woman)

Cell phones

The following factors have been proposed as possible risk factors for primary brain tumors Whether these factors actually increase the risk of a brain tumor is not known for sure.

Electromagnetic

Spectrum

Early analog phones (800-900 Mhz)

Digital phones

(up to

1900 MHz)

Biological Effects of Radiofrequency Radiation

• Energy of a radiofrequency (RF) wave from a cellular telephone is billions of times lower than the energy of

an x-ray photon

• RF radiation is insufficiently energetic to break

molecular bonds or ionize molecules

• At high power levels, RF radiation can cause heating, but biological effect from cellular phone use unlikely to

NCI Study – Methods

• Hospital-based, case-control study

• 3 hospitals (Phoenix, Pittsburgh, Boston)

• 782 newly-diagnosed cases (489 glioma,

197 meningioma, 96 acoustic neuroma)

• 799 matched controls

• Interview about use of cellular phones

• Data collection from 1994 to 1998

Cell-Phone Use and Risk of

Cell-Phone Use and Risk of

* Use for >= 6 months before tumor diagnosis

** Test for independence

Main Findings

• No association between incidence of glioma

and level of use of cell phone

• Laterality of cancer not related to laterality of

phone use

• Similar findings for meningioma & acoustic

neuroma

• Incident, histologically-confirmed cases

• Rapid case ascertainment

– Relatively few proxy interviews

• High participation rates (92% for cases,

86% for controls)

• Large sample size for glioma

• Use of imaging and surgical reports to

determine tumor location

• Small number of long-term, heavy users

• Cannot rule out small risks

• Reliance on interviews taken after tumor

diagnosis to assess cell phone use

– potential for imperfect recall (as in all

case-control studies)

• Changes in cellular technology

Changes in Cellular Networks

and Phones

• Analog versus digital

– First cell phones were analog

– Digital service began in the U.S in 1992; earlier in

Europe

– Current cell phones are digital

– Digital phones emit less RF energy per unit time – Adaptive power control

• Higher density of base station antennas

• Higher operating frequencies

Other studies

• Most existing studies found little or no

association between cell phone use and brain

cancer

• Existing studies are quite limited, therefore more studies are needed to establish cause and effect relationship

• Brain cancer incidence trends for brain cancer appears to be unrelated to cell phone use

• No consistent subgroup findings but need

larger numbers of longer-term users to

evaluate different exposure metrics, latency, laterality, etc

• There is a a need to evaluate consistency

within and among existing studies

• Further studies are needed to detect term risks and risks to children