Obesity and Thyroid Cancer

Obesity has repeatedly been cited as a possible etiologic factor in the pathogenesis of thyroid cancer and has been postulated to be a possible origin of the increase incidence of this disease worldwide.
Undeniably, being overweight and obesity have been associated with an increased risk of developing numerous malignancies, including thyroid, breast, colorectal, kidney, and endometrial cancers.
In the United States from 1995 to 2015, one out of every six PTC and two thirds of PTC greater than 4 cm in size have been linked to being overweight or obesity, based on an analysis of data from three large national US databases.
Kitahara et al projected that the total relative risk for PTC was 1.26 for persons who are overweight (body mass index [BMI] 25 to 29 kg/m2) and 1.30 for those who are obese (BMI ≥ 30 kg/m2), compared with persons with normal-weight BMI (18.5 to 24.9 kg/m2).
The risk in PTCs greater than 4 cm in size was nearly 3-fold higher (hazard ratio [HR] = 2.93, 95% CI 1.25-6.87) with overweight individuals, and more than 5-fold higher (HR = 5.42, 95% CI 2.24-13.1) in obese individuals compared with normal-weight individuals.
A study by Leitzmann et al, found that obese adults had a nearly 40% higher risk for developing thyroid cancer when compared with normal-weight individuals.
More research is needed to define the exact role of obesity in the development of thyroid cancer, particularly as the incidence of obesity continues to climb throughout the world.

References:
- Society, A.C., American Cancer Society: Cancer Facts and Figures 2018., A.C. Society, Editor. 2018: Atlanta, Ga.
- Brindel, P., et al., Anthropometric factors in differentiated thyroid cancer in French Polynesia: a case-control study.Cancer Causes Control, 2009. 20(5): p. 581-90.
- Dal Maso, L., et al., A pooled analysis of thyroid cancer studies. V. Anthropometric factors. Cancer Causes Control, 2000. 11(2): p. 137-44.
- Kitahara CM, P.R., Sosa JA, Shiels MS, Impact of overweight and obesity on U.S. papillary thyroid cancer incidence trends (1995-2015). J Natl Cancer Inst, 2019.
- Leitzmann, M.F., et al., Prospective study of body mass index, physical activity and thyroid cancer. Int J Cancer, 2010. 126(12): p. 2947-56.
- Berghofer, A., et al., Obesity prevalence from a European perspective: a systematic review. BMC Public Health, 2008. 8: p. 200.
- Wang, Y. and M.A. Beydoun, The obesity epidemic in the United States–gender, age, socioeconomic, racial/ethnic, and geographic characteristics: a systematic review and meta-regression analysis. Epidemiol Rev, 2007. 29: p. 6-28.