Study links exposure to nighttime artificial lights with elevated thyroid cancer risk

February 08, 2021

People living in regions with high levels of outdoor artificial light at night may face a higher risk of developing thyroid cancer. The finding comes from a study published early online in , a peer-reviewed journal of the American Cancer Society.

Over the past century, nightscapes--especially in cities--have drastically changed due to the rapid growth of electric lighting. Also, epidemiological studies have reported an association between higher satellite-measured levels of nighttime light and elevated breast cancer risk. Because some breast cancers may share a common hormone-dependent basis with thyroid cancer, a team led by Qian Xiao, PhD, of The University of Texas Health Science Center at Houston School of Public Health, looked for an association between light at night and later development of thyroid cancer among participants in the NIH-AARP Diet and Health Study, which recruited American adults aged 50 to 71 years in 1995-1996. The investigators analyzed satellite imagery data to estimate levels of light at night at participants' residential addresses, and they examined state cancer registry databases to identify thyroid cancer diagnoses through 2011.

Among 464,371 participants who were followed for an average of 12.8 years, 856 cases of thyroid cancer were diagnosed (384 in men and 472 in women). When compared with the lowest quintile of light at night, the highest quintile was associated with a 55 percent higher risk of developing thyroid cancer. The association was primarily driven by the most common form of thyroid cancer, called papillary thyroid cancer, and it was stronger in women than in men. In women, the association was stronger for localized cancer with no sign of spread to other parts of the body, while in men the association was stronger for more advanced stages of cancer. The association appeared to be similar for different tumor sizes and across participants with different sociodemographic characteristics and body mass index.

The researchers noted that additional epidemiologic studies are needed to confirm their findings. If confirmed, it will be important to understand the mechanisms underlying the relationship between light at night and thyroid cancer. The scientists noted that light at night suppresses melatonin, a modulator of estrogen activity that may have important anti-tumor effects. Also, light at night may lead to disruption of the body's internal clock (or circadian rhythms), which is a risk factor for various types of cancer.

"As an observational study, our study is not designed to establish causality. Therefore, we don't know if higher levels of outdoor light at night lead to an elevated risk for thyroid cancer; however, given the well-established evidence supporting a role of light exposure at night and circadian disruption, we hope our study will motivate researchers to further examine the relationship between light at night and cancer, and other diseases," said Dr. Xiao. "Recently, there have been efforts in some cities to reduce light pollution, and we believe future studies should evaluate if and to what degree such efforts impact human health."
-end-
Additional Information

NOTE: The information contained in this release is protected by copyright. Please include journal attribution in all coverage. A free abstract of this article will be available via the

Dawn Peters +1 781-388-8408 (US)
newsroom@wiley.com

Follow us on Twitter @WileyNews

Full Citation: "Associations between artificial light at night and risk for thyroid cancer: a large U.S. cohort study." Dong Zhang, Rena R. Jones, Peter James, Cari M. Kitahara, and Qian Xiao. CANCER; Published Online: February 8, 2021 (DOI: 10.1002/cncr.33392).

URL Upon Publication: http://doi.wiley.com/10.1002/cncr.33392

Author Contact: Wendi Hawthorne, Media Relations Specialist at The University of Texas Health Science Center at Houston, at wendi.hawthorne@uth.tmc.edu or +1 713-500-3030.

About the Journal

CANCER is a peer-reviewed publication of the American Cancer Society integrating scientific information from worldwide sources for all oncologic specialties. The objective of CANCER is to provide an interdisciplinary forum for the exchange of information among oncologic disciplines concerned with the etiology, course, and treatment of human cancer. CANCER is published on behalf of the American Cancer Society by Wiley and can be accessed online.

Follow us on Twitter @JournalCancer

About Wiley

Wiley drives the world forward with research and education. Through publishing, platforms and services, we help students, researchers, universities, and corporations to achieve their goals in an ever-changing world. For more than 200 years, we have delivered consistent performance to all of our stakeholders. The Company's website can be accessed at http://www.wiley.com.

Wiley

Related Developing Thyroid Cancer Articles from Brightsurf:

In-utero exposures associated with increased risk of thyroid cancer
A recent study shows that thyroid cancer is related to in-utero exposures.

Trends in the global burden of thyroid cancer
This study examined the worldwide trends of thyroid cancer from 1990 to 2017 according to geographic location, sex, age and socioeconomic factors.

Cancer treatment with immune checkpoint inhibitors may lead to thyroid dysfunction
Thyroid dysfunction following cancer treatment with new treatments called immune checkpoint inhibitors is more common than previously thought, according to research that was accepted for presentation at ENDO 2020, the Endocrine Society's annual meeting, and will be published in a special supplemental section of the Journal of the Endocrine Society.

Thyroid cancer, genetic variations, cell phones linked in YSPH study
Radiation from cell phones is associated with higher rates of thyroid cancer among people with genetic variations in specific genes, a new study led by the Yale School of Public Health finds.

AJR researchers take step toward automating thyroid cancer triage
An article published ahead-of-print in the April issue of the American Journal of Roentgenology (AJR) details how a Stanford University team developed a quantitative framework able to sonographically differentiate between benign and malignant thyroid nodules at a level comparable to that of expert radiologists, which could provide second-opinion malignancy risk estimation to clinicians and ultimately help decrease the number of unnecessary biopsies and surgical procedures.

Thyroid cancer rates in US
An analysis suggests rates of thyroid cancer in the US appear to have plateaued in recent years after decades on the rise.

Using artificial intelligence to predict risk of thyroid cancer on ultrasound
New study uses machine learning on ultrasound images of thyroid nodules to predict risk of malignancy.

For low-risk thyroid cancer patients, less may be more for post-surgery surveillance
Patient self-advocacy is important, and although a maximizing preference may be advantageous in many situations, new research led by the University of Michigan Rogel Cancer Center shows that, in the case of long-term surveillance of treated, low-risk thyroid cancer, health care ''maximizers'' consume more health care resources -- such as doctor visits and diagnostic imaging tests -- which drive up costs without a clear improvement in outcomes.

New test for thyroid cancer could prevent unnecessary surgery
Each year, thanks to inconclusive tests for thyroid cancer, thousands of people undergo unnecessary surgeries to remove part or all of their thyroids.

Raman spectroscopy poised to make thyroid cancer diagnosis less invasive
Researchers have demonstrated that an optical technique known as Raman spectroscopy can be used to differentiate between benign and cancerous thyroid cells.

Read More: Developing Thyroid Cancer News and Developing Thyroid Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.