Epidemiological study (observational study)

Mobile Phone Use and the Risk for Malignant Brain Tumors: A Case-Control Study on Deceased Cases and Controls epidem.

By: Hardell L, Carlberg M, Hansson Mild K

Published in: Neuroepidemiology 2010; 35 (2): 109-114

Aim of study (acc. to author)

A case-control study on deceased cases and controls was conducted in Sweden to investigate the association between the use of mobile phones or cordless phones and the risk for malignant brain tumors.

Further details

The cases analyzed in the present study were excluded in the publication of Hardell et al 2006 because they died before they could be interviewed about their mobile phone use.
Exposure of the cases and controls was assessed by a questionnaire sent to the next-of-kin (wife or husband, child, parent, sibling or other relative).

Endpoint/type of risk estimation

brain tumor: malignant brain tumor

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

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

Assessment

questionnaire: type of mobile phone (analog or digital), mean minutes of daily use over the years, use in a car with external antenna or a hands-free device; years of use and mean number of minutes per day of cordless phone use
calculation: cumulative lifetime use

Exposure groups

Group	Description
Reference group 1	unexposed
Group 2	analog mobile phone use > 1 to 5 years
Group 3	analog mobile phone use > 5 to 10 years
Group 4	analog mobile phone use > 10 years
Group 5	analog mobile phone use > 1 year (group 2+3+4)
Group 6	analog mobile phone use ≤ 149 h, > 1 to 5 years
Group 7	analog mobile phone use ≤ 149 h, > 5 to 10 years
Group 8	analog mobile phone use ≤ 149 h, >10 years
Group 9	analog mobile phone use ≤ 149 h, >1 year
Group 10	analog mobile phone use > 149 h, > 1 to 5 years
Group 11	analog mobile phone use > 149 h, > 5 to 10 years
Group 12	analog mobile phone use > 149 h, >10 years
Group 13	analog mobile phone use > 149 h, >1 year
Group 14	digital mobile phone use > 1 to 5 years
Group 15	digital mobile phone use > 5 to 10 years
Group 16	digital mobile phone use >10 years
Group 17	digital mobile phone use >1 year
Group 18	digital mobile phone use ≤ 183 h, > 1 to 5 years
Group 19	digital mobile phone use ≤ 183 h, > 5 to 10 years
Group 20	digital mobile phone use ≤ 183 h, >10 years
Group 21	digital mobile phone use ≤ 183 h, >1 year
Group 22	digital mobile phone use > 183 h, > 1 to 5 years
Group 23	digital mobile phone use > 183 h, > 5 to 10 years
Group 24	digital mobile phone use > 183 h, >10 years
Group 25	digital mobile phone use > 183 h, >1 year
Group 26	mobile phone (analog and digital) use > 1 to 5 years
Group 27	mobile phone use > 5 to 10 years
Group 28	mobile phone use >10 years
Group 29	mobile phone use >1 year
Group 30	mobile phone use ≤ 176 h, > 1 to 5 years
Group 31	mobile phone use ≤ 176 h, > 5 to 10 years
Group 32	mobile phone use ≤ 176 h, >10 years
Group 33	mobile phone use ≤ 176 h, >1 year
Group 34	mobile phone use > 176 h, > 1 to 5 years
Group 35	mobile phone use > 176 h, > 5 to 10 years
Group 36	mobile phone use > 176 h, >10 years
Group 37	mobile phone use > 176 h, >1 year
Group 38	cordless phone use > 1 to 5 years
Group 39	cordless phone use > 5 to 10 years
Group 40	cordless phone use >10 years
Group 41	cordless phone use >1 year
Group 42	cordless phone use ≤ 548 h, > 1 to 5 years
Group 43	cordless phone use ≤ 548 h, > 5 to 10 years
Group 44	cordless phone use ≤ 548 h, >10 years
Group 45	cordless phone use ≤ 548 h, >1 year
Group 46	cordless phone use > 548 h, > 1 to 5 years
Group 47	cordless phone use > 548 h, > 5 to 10 years
Group 48	cordless phone use > 548 h, >10 years
Group 49	cordless phone use > 548 h, >1 year
Group 50	mobile + cordless phone use > 1 to 5 years
Group 51	mobile + cordless phone use > 5 to 10 years
Group 52	mobile + cordless phone use >10 years
Group 53	mobile + cordless phone use >1 year
Group 54	mobile + cordless phone use ≤ 410 h, > 1 to 5 years
Group 55	mobile + cordless phone use ≤ 410 h, > 5 to 10 years
Group 56	mobile + cordless phone use ≤ 410 h, >10 years
Group 57	mobile + cordless phone use ≤ 410 h, >1 year
Group 58	mobile + cordless phone use > 410 h, > 1 to 5 years
Group 59	mobile + cordless phone use > 410 h, > 5 to 10 years
Group 60	mobile + cordless phone use > 410 h, >10 years
Group 61	mobile + cordless phone use > 410 h, >1 year
Group 62	analog mobile phone, cumulative lifetime use: 1 - 1,000 h
Group 63	analog mobile phone, cumulative lifetime use: 1,001 - 2,000 h
Group 64	analog mobile phone, cumulative lifetime use: > 2,000 h
Group 65	digital mobile phone, cumulative lifetime use: 1 - 1,000 h
Group 66	digital mobile phone, cumulative lifetime use: 1,001 - 2,000 h
Group 67	digital mobile phone, cumulative lifetime use: > 2,000 h
Group 68	mobile phone, cumulative lifetime use: 1 - 1,000 h
Group 69	mobile phone, cumulative lifetime use: 1,001 - 2,000 h
Group 70	mobile phone, cumulative lifetime use: > 2,000 h
Group 71	cordless phone, cumulative lifetime use: 1 - 1,000 h
Group 72	cordless phone, cumulative lifetime use: 1,001 - 2,000 h
Group 73	cordless phone, cumulative lifetime use: > 2,000 h
Group 74	mobile + cordless phone, cumulative lifetime use: 1 - 1,000 h
Group 75	mobile + cordless phone, cumulative lifetime use: 1,001 - 2,000 h
Group 76	mobile + cordless phone, cumulative lifetime use: > 2,000 h

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
Exclusion criteria: patient was able to be interviewed; cases died in 2003

Control group

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

Study size

	Cases	Controls
Participants	346	619
Participation rate	75 %	67 %

Statistical analysis method:

unconditional logistic regression

(adjustment:

5-year age group
sex
socioeconomic status
year of diagnosis

)

Results (acc. to author)

A statistically significant increased risk of malignant brain tumors was observed among the group of diseased mobile phone users (only analog mobile phone in group 4, analog and digital mobile phone in group 28, digital mobile phone in group 16 (only 2 cases and no controls, calculation of OR not possible), highest in the group with mobile phone use of more than 176 h and a latency time of more than 10 years (group 36). No statistically significant increased risk was observed for cordless phones (groups 38-49).
The authors concluded that the investigation confirmed previous results of an association between mobile phone use and malignant brain tumors.

Limitations (acc. to author)

Only few subjects have used digital mobile phones for more than 10 years.

Study funded by

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

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