Epidemiological study (observational study)

Pooled analysis of case-control studies on malignant brain tumours and the use of mobile and cordless phones including living and deceased subjects epidem.

By: Hardell L, Carlberg M, Hansson Mild K

Published in: Int J Oncol 2011; 38 (5): 1465-1474

Aim of study (acc. to author)

A pooled analysis of three case-control studies on the use of mobile phones and cordless phones and the risk of malignant brain tumors was conducted in Sweden.

Further details

Cases who died before they could be interviewed about their mobile phone use were excluded in the publication of Hardell et al (2006) which might have led to bias. Therefore following studies were included in the present pooled-analysis including all alive and deceased cases between 1997-2003: The first case-control study regarding the period 1997-2000 was published in the publications 9520 and 9895, the second study regarding the period 2000-2003 in publications 12068 and 12259, and the third study regarding deceased cases and controls in the period 1997-2003 in publication 18358.

Endpoint/type of risk estimation

brain tumor: malignant brain tumors: glioma, meningioma, astrocytoma, oligodendroglioma

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

- mobile communications
- analog mobile phone
- digital mobile phone
- cordless phone
- personal

Assessment

questionnaire: use of mobile phone and cordless phone, first year of use, type of phone, mean minutes of daily use

Exposure groups

Group	Description
Reference group 1	unexposed: no mobile or cordless phone use or less than 1 year
Group 2	mobile + cordless phone use ≤ 195 h, > 1 to 5 years
Group 3	mobile + cordless phone use ≤ 195 h, > 5 to 10 years
Group 4	mobile + cordless phone use ≤ 195 h, > 10 years
Group 5	mobile + cordless phone use ≤ 195 h, total, > 1 year
Group 6	mobile + cordless phone use > 195 h, > 1 to 5 years
Group 7	mobile + cordless phone use > 195 h, > 5 to 10 years
Group 8	mobile + cordless phone use > 195 h, > 10 years
Group 9	mobile + cordless phone use > 195 h, total, > 1 year
Group 10	mobile phone use ≤ 74 h, > 1 to 5 years
Group 11	mobile phone use ≤ 74 h, > 5 to 10 years
Group 12	mobile phone use ≤ 74 h, > 10 years
Group 13	mobile phone use ≤ 74 h, total, > 1 year
Group 14	mobile phone use > 74 h, > 1 to 5 years
Group 15	mobile phone use > 74 h, > 5 to 10 years
Group 16	mobile phone use > 74 h, > 10 years
Group 17	mobile phone use > 74 h, total, > 1 year
Group 18	cordless phone use ≤ 243 h, > 1 to 5 years
Group 19	cordless phone use ≤ 243 h, > 5 to 10 years
Group 20	cordless phone use ≤ 243 h, > 10 years
Group 21	cordless phone use ≤ 243 h, total, > 1 year
Group 22	cordless phone use > 243 h, > 1 to 5 years
Group 23	cordless phone use > 243 h, > 5 to 10 years
Group 24	cordless phone use > 243 h, > 10 years
Group 25	cordless phone use > 243 h, total, > 1 year
Group 26	mobile + cordless phone, cumulative lifetime use: 1 - 1,000 h
Group 27	mobile + cordless phone, cumulative lifetime use: 1,001 - 2,000 h
Group 28	mobile + cordless phone, cumulative lifetime use: > 2,000 h
Group 29	mobile phone, cumulative lifetime use: 1 - 1,000 h
Group 30	mobile phone, cumulative lifetime use: 1,001 - 2,000 h
Group 31	mobile phone, cumulative lifetime use: > 2,000 h
Group 32	cordless phone, cumulative lifetime use: 1 - 1,000 h
Group 33	cordless phone, cumulative lifetime use: 1,001 - 2,000 h
Group 34	cordless phone, cumulative lifetime use: > 2,000 h
Group 35	mobile + cordless phone use, > 1 to 5 years
Group 36	mobile + cordless phone use, > 5 to 10 years
Group 37	mobile + cordless phone use, > 10 years
Group 38	mobile + cordless phone use, total, > 1 year
Group 39	mobile phone use, > 1 to 5 years
Group 40	mobile phone use, > 5 to 10 years
Group 41	mobile phone use, > 10 years
Group 42	mobile phone use, total, > 1 year
Group 43	cordless phone use, > 1 to 5 years
Group 44	cordless phone use, > 5 to 10 years
Group 45	cordless phone use, > 10 years
Group 46	cordless phone use, total, > 1 year
Group 47	mobile + cordless phone use, first use < 20 years old
Group 48	mobile + cordless phone use, first use 20 - 49 years old
Group 49	mobile + cordless phone use, first use ≥ 50 years old
Group 50	mobile phone use, first use < 20 years old
Group 51	mobile phone use, first use 20 - 49 years old
Group 52	mobile phone use, first use ≥ 50 years old
Group 53	cordless phone use, first use < 20 years old
Group 54	cordless phone use, first use 20 - 49 years old
Group 55	cordless phone use, first use ≥ 50 years old

Population

Group:
- men
- women
Age: 20–80 years
Observation period: 1997 - 2003
Study location: Sweden (Uppsala/Örebro and Linköping medical regions 1997-2003, Stockholm and Gothenburg regions 1997-2000)

Case group

Characteristics: brain tumor, histopathologically verified
Data source: Cancer registry

Control group

group 1: living person, group 2: died from other types of malignant diseases than brain tumor, group 3: died from other diseases than cancer
Selection:
- population-based
- registry-based
Matching:
- sex
- age
- area
- year of death

Study size

	Cases	Controls
Eligible	1,472	2,900
Participants	1,251	2,438
Participation rate	85 %	84 %

Statistical analysis method:

unconditional logistic regression

(adjustment:

age
sex
socioeconomic status
year of diagnosis, vital status (alive or deceased)

)

Results (acc. to author)

The main result of this pooled analysis was an increased risk for malignant brain tumor and the use of both mobile phones and cordless phones. The highest risk was observed for the most common type of glioma, astrocytoma, in the > 10 years latency group for mobile phones use (OR 2.7, CI 1.9-3.7) and for cordless phone use (OR 1.8, CI 1.2-2.9). The risk for astrocytoma was highest in the group with first use of a mobile phone or cordless phone before the age of 20 (mobile phone use: OR 4.9, CI 2.2-11; cordless phone use: OR 3.9, CI 1.7-8.7).
The authors concluded that the risk for malignant brain tumors increased with latency time and cumulative use of mobile phones and cordless phones in hours and was highest in subjects with first use before the age of 20.

Study funded by

Cancer och Allergifonden (Cancer and Allergy Foundation), Sweden
Cancerhjälpen (Cancerhelp), Sweden

Comments on this article

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