Study type: Epidemiological study (observational study)

Correlation between cellular phone use and epithelial parotid gland malignancies. epidem.

Published in: Int J Oral Maxillofac Surg 2011; 40 (9): 966-972

Aim of study (acc. to author)

A case-control study was conducted in China to investigate the association between cellular phone use and epithelial parotid gland malignancy.

Further details

Regular exposure was defined as at least one call per week for 6 months or more before the time of diagnosis.

Endpoint/type of risk estimation

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

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 frequency of use: never or rarely
Group 2 frequency of use: regular use
Reference group 3 duration since first use to the time of diagnosis: never or rarely
Group 4 duration since first use to the time of diagnosis: 0.5 - 6 years
Group 5 duration since first use to the time of diagnosis: 7 - 8 years
Group 6 duration since first use to the time of diagnosis: 9 - 10 years
Group 7 duration since first use to the time of diagnosis: > 10 years
Reference group 8 calculated duration of cellular phone use: never or rarely
Group 9 calculated duration of cellular phone use: 0.5 - 6 years
Group 10 calculated duration of cellular phone use: 7 - 8 years
Group 11 calculated duration of cellular phone use: 9 - 10 years
Group 12 calculated duration of cellular phone use: > 10 years
Reference group 13 average daily use: never or rarely
Group 14 average daily use: ≤ 0.5 hours
Group 15 average daily use: 0.5 - 2.5 hours
Group 16 average daily use: > 2.5 hours
Reference group 17 average daily longest time of a single call: never or rarely
Group 18 average daily longest time of a single call: ≤ 0.5 hours
Group 19 average daily longest time of a single call: 0.5 - 2.5 hours
Group 20 average daily longest time of a single call: > 2.5 hours
Reference group 21 average daily number of calls: never or rarely
Group 22 average daily number of calls: ≤ 8
Group 23 average daily number of calls: 9 - 10
Group 24 average daily number of calls: > 10
Reference group 25 number of calls since first use: never or rarely
Group 26 number of calls since first use: ≤ 24,000
Group 27 number of calls since first use: 24,001 - 42,000
Group 28 number of calls since first use: > 42,000
Reference group 29 time of calls since first use: never or rarely
Group 30 time of calls since first use: ≤ 1350 hours
Group 31 time of calls since first use: 1351 - 4320 hours
Group 32 time of calls since first use: > 4320 hours
Reference group 33 preferred side of calling: never or rarely
Group 34 preferred side of calling: ipsilateral
Group 35 preferred side of calling: contralateral
Group 36 preferred side of calling: ipsilateral and contralateral

Population

Case group

Control group

Study size

Cases Controls
Eligible 221 2,643
Participants 136 2,051
Participation rate 62 % 78 %
Statistical analysis method:

Conclusion (acc. to author)

Overall (between reference group 1 and group 2), frequency of cellular phone use was not significantly associated with parotid gland malignancy . However, statistically significant associations were observed in subgroups of the univariate analysis (e.g., duration since first use > 10 years, average daily use > 2.5 hours, calculated duration of use > 10 years) and in subgroups of the multivariate analysis (e.g., number of calls since first use > 42,000 (OR 15.4, CI 13.3-17.4), calculated duration of use 9-10 years (OR 7.7, CI 6.2-9.2), average daily use > 2.5 hours (OR 6.0, CI 1.5-24.5).
Female gender, advanced age, married status, higher education, higher monthly income, and smoking were associated with increased risk of epithelial parotid gland malignancy, especially mucoepidermoid carcinoma.
No statistically significant association between ipsilateral cellular phone use and epithelial parotid gland malignancies was found which indicates that a definitve conclusion about cellular phone use and parotid gland malignancy cannot be made.
The authors conclude that the results suggest a possible dose-response relationship of cellular phone use with epithelial parotid gland malignancy. They suggest that the association of cellular phone use and epithelial parotid gland malignancy requires further investigation with large prospective studies to reduce bias and confirm the results.

Limitations (acc. to author)

Selection bias and recall bias cannot be excluded. Regular use was defined as at least one call per week for 6 months or more prior diagnosis, whereas epithelial parotid gland malignancies are not likely to be induced by such a short exposure time, so this might have led to misclassification bias.

Study funded by

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