BACKGROUND
The incidence of thyroid cancer has increased approximately by 10% per year over the past 30 years, and according to Global Cancer Statistics, thyroid cancer ranks 9th among 36 cancers globally. Being diagnosed with thyroid cancer takes not only an emotional toll, but also a significant financial toll not just for individuals but for the whole US health care system. In fact, a thyroid cancer diagnosis and its long term management are the reasons for one of the highest bankruptcy rates among patients with cancer. It is likely that a combination of genetic and environmental factors increase the likelihood for a particular individual to develop thyroid cancer. Among the well-established thyroid cancer risk factors include a family history, exposure to ionizing radiation, and in recent data, an association with obesity. Lifestyle factors, such as physical activity, smoking, alcohol and diet have been proposed to affect thyroid cancer incidence, but published studies have shown mixed results.

This study was done to explore the association between lifestyle, genetic factors and the risk for thyroid cancer, and also to address the question of whether lifestyle modification could reduce the risk for developing thyroid cancer.

THE FULL ARTICLE TITLE
Feng X et al 2022 Association Between Genetic Risk, Adherence to Healthy Lifestyle Behavior, and Thyroid Cancer Risk. JAMA Netw Open 5(12):e2246311.

SUMMARY OF THE STUDY
This study used the UK Biobank data and included 264,956 participants aged 40-69 years who were followed for approximately 11 years and for whom genetic data and clinical information were available. Applying statistical methods, a genetic risk score was generated. A lifestyle score was generated based on self-reported data for weight, diet, physical activity, smoking and alcohol consumption and categorized as unfavorable, intermediate or favorable. The associations between the genetic score, lifestyle, and thyroid cancer incidence as well as the interactions between them were tested.

During the follow up of 11.1 years, 423 cases of thyroid cancer were reported. The incidence rate was almost 3 fold higher in women than in men. The higher genetic score was associated with an increased risk for thyroid cancer. Independently, an unfavorable lifestyle was also associated with a higher risk of thyroid cancer. Individuals who had both the high genetic score and the unfavorable lifestyle score had the highest risk for thyroid cancer. Interestingly, among the patients who had the highest genetic score, a favorable lifestyle reduced thyroid cancer risk.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study suggests that genetic and lifestyle factors are independently associated with thyroid cancer incidence, and that a healthy lifestyle can help reduce risk for developing thyroid cancer in patients who have a high genetic predisposition. This study is important for patients because it provides evidence that even when there is a strong genetic predisposition, they can help reduce their personal risk to develop thyroid cancer by engaging in a healthy lifestyle.

— Jesse Block-Galaraza, MD

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