Air Pollution May Be Linked to Increased Occurrence of Thyroid Cancer

According to results from a nested case-control study, exposure to meteorological conditions, including air pollution, may affect the occurrence of thyroid cancer (Sci Rep. 2021 Nov 3;11(1):21562.). 

“Several environmental factors suggested to be endocrine disruptors have been associated with the occurrence of thyroid cancer,” explained Sung Joon Park, Chung-Ang University College of Medicine, Seoul, Republic of Korea, and colleagues “...However, only a few reports support the potential association between air pollution and thyroid cancer”. 

The study included 4632 patients with thyroid cancer and 18,528 control subjects, who were matched at a 1:4 ratio by age, sex, income, and region of residence. Additionally, researchers used the Korean National Health Insurance Service-Health Screening Cohort data from 2002 to 2015.

The odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for thyroid cancer correlated with air pollution exposure over a moving average of 3 years before the index dates.

Results showed that the adjusted ORs associated with relative humidity (1.01, 95% CI 1.00–1.03, P=0.023), ambient atmospheric pressure (1.02, 95% CI 1.01–1.03, P< 0.001), and sunshine duration (1.17, 95% CI 1.04–1.31, P= 0.007) indicated correlations with the occurrence of thyroid cancer for all patients involved. However, researchers found these results inconsistent in the subgroup analyses.

Furthermore, in patients under 60 years old, nitrogen dioxide (NO2) and showed a higher OR (1.52, 95% CI 1.33–1.73) than in patients 60 or older (1.03, 95% CI 1.02–1.04), as did particular matter (PM10; 0.66, 95% CI 0.59–0.73). Despite these findings, the positive association of NO2 and the negative association of PM10 was consistent in both age groups.

“The mean concentration of NO2 in the 3 years before the onset of thyroid cancer was significantly related to an increased risk of thyroid cancer in the thyroid cancer group, while the mean concentration of PM10 was associated with a significantly decreased risk in the thyroid cancer group compared to that in the control group,” concluded Dr Park et al.—Alexandra Graziano