Epidemiological study (observational study)

Pooled analysis of two case-control studies on the use of cellular and cordless telephones and the risk of benign brain tumours diagnosed during 1997-2003.

Published in: Int J Oncol 2006; 28 (2): 509-518

Aim of study (acc. to author)

A pooled analysis of two previous case-control studies on the use of cellular and cordless telephones and the risk of benign brain tumors was conducted in Sweden.

Further details

The first case-control study regarding the period 1997-2000 was published in the publications 9105 and 9520. The second study regarding the period 2000-2003 was published in publication 12068 concerning benign brain tumors and in publication 12259 concerning malignant brain tumors.

Endpoint/type of risk estimation

Type of risk estimation:
  • incidence
(odds ratio (OR))

Exposure

Assessment

  • questionnaire: first year of use, type of phone, mean minutes of daily use over the years, use in a car with external antenna or a hands-free, ear most frequently used
  • interview: supplementing data

Exposure groups

Reference group 1 unexposed
Group 2 analog > 1- to 5-year latency period
Group 3 analog > 5- to 10-year latency period
Group 4 analog > 10-year latency period
Group 5 analog > 15-year latency period
Group 6 analog total, > 1-year latency period
Group 7 analog ≤ 85 h, > 1- to 5-year latency period
Group 8 analog ≤ 85 h, > 5- to 10-year latency period
Group 9 analog ≤ 85 h, > 10-year latency period
Group 10 analog ≤ 85 h, total, > 1-year latency period
Group 11 analog > 85 h, > 1- to 5-year latency period
Group 12 analog > 85 h, > 5- to 10-year latency period
Group 13 analog > 85 h, > 10-year latency period
Group 14 analog > 85 h, total, > 1-year latency period
Group 15 digital > 1- to 5-year latency period
Group 16 digital > 5- to 10-year latency period
Group 17 digital > 10-year latency period
Group 18 digital total, > 1-year latency period
Group 19 digital ≤ 64 h, > 1- to 5-year latency period
Group 20 digital ≤ 64 h, > 5- to 10-year latency period
Group 21 digital ≤ 64 h, > 10-year latency period
Group 22 digital ≤ 64 h, total, > 1-year latency period
Group 23 digital > 64 h, > 1- to 5-year latency period
Group 24 digital > 64 h, > 5- to 10-year latency period
Group 25 digital > 64 h, > 10-year latency period
Group 26 digital > 64 h, total, > 1-year latency period
Group 27 cordless > 1- to 5-year latency period
Group 28 cordless > 5- to 10-year latency period
Group 29 cordless > 10-year latency period
Group 30 cordless total, > 1-year latency period
Group 31 cordless ≤ 195 h, > 1- to 5-year latency period
Group 32 cordless ≤ 195 h, > 5- to 10-year latency period
Group 33 cordless ≤ 195 h, > 10-year latency period
Group 34 cordless ≤ 195 h, total, > 1-year latency period
Group 35 cordless > 195 h, > 1- to 5-year latency period
Group 36 cordless > 195 h, > 5- to 10-year latency period
Group 37 cordless > 195 h, > 10-year latency period
Group 38 cordless > 195 h, total, > 1-year latency period

Population

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

Case group

Control group

  • Matching:
    • sex
    • age
    • area

Study size

Cases Controls
Eligible 1,429 2,437
Participants 1,254 2,162
Participation rate 88 89
Other: benign and malignant brain tumors total: 2437, controls for malignant and benign cases
Statistical analysis method:
  • unconditional logistic regression
( adjustment:
  • age
  • 5-year age group
  • socioeconomic status
  • year of diagnosis
)

Conclusion (acc. to author)

The results showed an increased risk of benign brain tumors, especially acoustic neuroma. The highest risk for acoustic neuroma was found for a latency period of more than 15 years for use of analog cellular phones. No convincing pattern of association was observed for other types of benign brain tumors.

Limitations (acc. to author)

Several calculations were based on low numbers.

Study funded by

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

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