Associations between artificial light at night and risk for thyroid cancer: A large US cohort study

PAPER manual Cancer 2021 Cohort study Effect: harm Evidence: Moderate

Read original paper → DOI: 10.1002/cncr.33392 PMID: 33554351 Evidence Lab

Abstract

Associations between artificial light at night and risk for thyroid cancer: A large US cohort study Dong Zhang, Rena R Jones, Peter James, Cari M Kitahara, Qian Xiao. Associations between artificial light at night and risk for thyroid cancer: A large US cohort study. Cancer. 2021 Feb 8. doi: 10.1002/cncr.33392. Abstract Background: Light at night (LAN) inhibits nighttime secretion of melatonin and may cause circadian disruption, which may be a risk factor for cancer. Recent studies have linked high LAN exposure with elevated breast cancer risk. Given that breast cancer may share a common hormone-dependent etiology with thyroid cancer and that circadian rhythms play a role in regulating thyroid function, the authors hypothesized that exposure to LAN is positively associated with thyroid cancer incidence. Methods: This study examined the association between LAN and thyroid cancer incidence in the National Institutes of Health-American Association of Retired Persons Diet and Health Study. LAN exposure was estimated from satellite data and was linked to residential addresses at the baseline. Incident thyroid cancer cases were ascertained via linkage to state cancer registries. Cox regression was used to determine the relationship between LAN and thyroid cancer risk, with adjustments made for sociodemographic, lifestyle, and other environmental factors. Results: Among 464,371 participants, a positive association was found between LAN and thyroid cancer risk. Specifically, in comparison with the lowest quintile of LAN, the highest quintile was associated with a 55% increase in risk (hazard ratio [HR], 1.55; 95% confidence interval [CI], 1.18-2.02). The association was primarily driven by papillary thyroid cancer and was stronger in women (HR, 1.81; 95% CI, 1.26-2.60) than men (HR, 1.29; 95% CI, 0.86-1.94). In women, the association was stronger for localized cancer, whereas in men, the association was stronger for a more advanced stage. Results were consistent across different tumor sizes. Conclusions: LAN was positively associated with thyroid cancer risk. Future studies are needed to confirm this association and identify underlying biological mechanisms. pubmed.ncbi.nlm.nih.gov

AI evidence extraction

At a glance

Study type

Cohort study

Effect direction

harm

Population

Participants in the NIH-AARP Diet and Health Study (US cohort)

Sample size

464371

Exposure

artificial light at night (LAN)

Evidence strength

Moderate

Confidence: 78% · Peer-reviewed: yes

Main findings

Higher satellite-estimated residential light at night (LAN) exposure was associated with higher thyroid cancer incidence. Compared with the lowest LAN quintile, the highest quintile had increased risk (HR 1.55, 95% CI 1.18-2.02), with a stronger association in women (HR 1.81, 95% CI 1.26-2.60) than men (HR 1.29, 95% CI 0.86-1.94); the association was primarily driven by papillary thyroid cancer.

Outcomes measured

Incident thyroid cancer
Papillary thyroid cancer
Thyroid cancer stage (localized vs more advanced)
Tumor size (thyroid cancer)

Limitations

LAN exposure estimated from satellite data and linked to baseline residential address (potential exposure misclassification)
Observational design (cannot establish causality)
Authors note that future studies are needed to confirm the association and identify mechanisms

View raw extracted JSON

{
    "study_type": "cohort",
    "exposure": {
        "band": null,
        "source": "artificial light at night (LAN)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Participants in the NIH-AARP Diet and Health Study (US cohort)",
    "sample_size": 464371,
    "outcomes": [
        "Incident thyroid cancer",
        "Papillary thyroid cancer",
        "Thyroid cancer stage (localized vs more advanced)",
        "Tumor size (thyroid cancer)"
    ],
    "main_findings": "Higher satellite-estimated residential light at night (LAN) exposure was associated with higher thyroid cancer incidence. Compared with the lowest LAN quintile, the highest quintile had increased risk (HR 1.55, 95% CI 1.18-2.02), with a stronger association in women (HR 1.81, 95% CI 1.26-2.60) than men (HR 1.29, 95% CI 0.86-1.94); the association was primarily driven by papillary thyroid cancer.",
    "effect_direction": "harm",
    "limitations": [
        "LAN exposure estimated from satellite data and linked to baseline residential address (potential exposure misclassification)",
        "Observational design (cannot establish causality)",
        "Authors note that future studies are needed to confirm the association and identify mechanisms"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "light at night",
        "LAN",
        "circadian disruption",
        "melatonin",
        "thyroid cancer",
        "papillary thyroid cancer",
        "NIH-AARP Diet and Health Study",
        "satellite exposure assessment",
        "cohort",
        "Cox regression"
    ],
    "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract/metadata and may be incomplete or incorrect. This content is for informational purposes only and is not medical advice.

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