Beginning in the early 1990’s, rates of thyroid cancer began to drastically increase. Though this trend has continued to the present day, many experts attribute the increase to marked improvements in methods of detecting thyroid cancer. While in previous decades, most diagnosed thyroid cancer cases were ones where the patient was experiencing substantial symptoms, today many cases of thyroid cancer are caught at the preclinical stage when the cancer is small and symptoms are not present.
This trend raises multiple questions in the oncology sphere. For one, thyroid cancer mortality has continued to increase despite improved treatment options and the trend towards earlier diagnosis. This is likely due to changing environmental factors such as increased exposure to radiation and carcinogens on a population level. Increased thyroid cancer mortality rates primarily affect a subset of patients with advanced cancer at the time of diagnosis.
In order to understand increases in mortality and diagnosis, researchers are seeking to pinpoint when and why thyroid cancer is diagnosed. This could help researchers understand whether rates of mortality and incidence remain generally stagnant despite major changes in how thyroid cancer is diagnosed and when a death is attributed to a diagnosis, or whether rates of aggressive thyroid cancers are truly increasing.
In a study examining 1,328 thyroid cancer patients, the researchers noted that 40.8% of patients had surgery for thyroid findings while being asymptomatic. This was higher than the percentage of patients (34%) who had surgery for thyroid findings while being symptomatic. In the United States and Canada, rates of patients undergoing surgery while asymptomatic were significantly higher than in South Africa and Denmark.
Unnecessary tests and treatments for thyroid symptoms are thought by some to cause more harm than good. The Choosing Wisely campaign provides clinicians with a list of guidelines for patients presenting with thyroid symptoms, which includes using restraint when ordering tests such as biopsies, CT scans, and ultrasounds for patients with minimal symptoms such as hoarseness and pain while swallowing.
Though it is still unclear which methods of diagnosis and treatment are most effective long term, epidemiological studies are essential in understanding trends related to thyroid cancer. In cases where thyroid cancer is detected incidentally, it may be most appropriate to limit overtreatment.
Sources: Journal of Cancer Epidemiology, Journal of Otolaryngology - Head & Neck Surgery, Journal of Otolaryngology - Head & Neck Surgery