Is the Increasing Incidence of Thyroid Cancer in the Nordic Countries Caused by Use of Mobile Phones?

Abstract

The International Agency for Research on Cancer (IARC) at the World Health Organization (WHO) categorized in 2011 radiofrequency (RF) as a possible human carcinogen, Group 2B. During use of the handheld wireless phone, especially the smartphone, the thyroid gland is a target organ. During the 21st century, the incidence of thyroid cancer is increasing in many countries. We used the Swedish Cancer Register to study trends from 1970 to 2017. During that time period, the incidence increased statistically significantly in women with average annual percentage change (AAPC) +2.13%, 95% confidence interval (CI) +1.43, +2.83%. The increase was especially pronounced during 2010-2017 with annual percentage change (APC) +9.65%, 95% CI +6.68, +12.71%. In men, AAPC increased during 1970-2017 with +1.49%, 95% CI +0.71, +2.28%. Highest increase was found for the time period 2001-2017 with APC +5.26%, 95% CI +4.05, +6.49%. Similar results were found for all Nordic countries based on NORDCAN 1970-2016 with APC +5.83%, 95% CI +4.56, +7.12 in women from 2006 to 2016 and APC + 5.48%, 95% CI +3.92, +7.06% in men from 2005 to 2016. According to the Swedish Cancer Register, the increasing incidence was similar for tumors ≤4 cm as for tumors >4 cm, indicating that the increase cannot be explained by overdiagnosis. These results are in agreement with recent results on increased thyroid cancer risk associated with the use of mobile phones. We postulate that RF radiation is a causative factor for the increasing thyroid cancer incidence.

AI evidence extraction

Main findings

Using Swedish Cancer Register data (1970–2017) and NORDCAN data for Nordic countries (1970–2016), thyroid cancer incidence increased statistically significantly in women and men, with particularly pronounced increases in more recent periods (e.g., 2010–2017 in Swedish women; 2001–2017 in Swedish men; mid-2000s to 2016 in Nordic countries). The Swedish Cancer Register showed similar increases for tumors ≤4 cm and >4 cm, which the authors interpret as arguing against overdiagnosis; they state the results align with reports of increased thyroid cancer risk with mobile phone use and postulate RF radiation as a causative factor.

Outcomes measured

• Thyroid cancer incidence trends (AAPC/APC)

Limitations

• Ecological/time-trend analysis; no individual-level mobile phone exposure assessment described in the abstract
• Potential confounding factors and alternative explanations (e.g., changes in risk factors, diagnostics, reporting) are not detailed in the abstract
• Causal inference is asserted ("postulate") but individual-level association is not presented in the abstract

Suggested hubs

• who-icnirp (0.32)
  Abstract references IARC/WHO 2011 classification of RF as Group 2B.

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    },
    "population": "Nordic countries (including Sweden); thyroid cancer incidence trends in men and women",
    "sample_size": null,
    "outcomes": [
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    ],
    "main_findings": "Using Swedish Cancer Register data (1970–2017) and NORDCAN data for Nordic countries (1970–2016), thyroid cancer incidence increased statistically significantly in women and men, with particularly pronounced increases in more recent periods (e.g., 2010–2017 in Swedish women; 2001–2017 in Swedish men; mid-2000s to 2016 in Nordic countries). The Swedish Cancer Register showed similar increases for tumors ≤4 cm and >4 cm, which the authors interpret as arguing against overdiagnosis; they state the results align with reports of increased thyroid cancer risk with mobile phone use and postulate RF radiation as a causative factor.",
    "effect_direction": "harm",
    "limitations": [
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        "Potential confounding factors and alternative explanations (e.g., changes in risk factors, diagnostics, reporting) are not detailed in the abstract",
        "Causal inference is asserted (\"postulate\") but individual-level association is not presented in the abstract"
    ],
    "evidence_strength": "very_low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "thyroid cancer",
        "incidence trends",
        "Nordic countries",
        "Swedish Cancer Register",
        "NORDCAN",
        "radiofrequency",
        "RF radiation",
        "mobile phones",
        "smartphone",
        "IARC Group 2B"
    ],
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