Aggressive Thyroid Screening/Treatment Not Associated With Higher Survival

A population-based study led by Cedars-Sinai investigators found that thyroid cancer continues to be overdiagnosed, while the risk of dying from the disease has remained the same.

A retrospective, population-based study led by Cedars-Sinai investigators has found that aggressive screening and treatment for thyroid cancer has not led to higher survival rates, according to results published in The Lancet Diabetes and Endocrinology.¹ Additionally, despite thyroid cancer incidences leveling off, it continues to be overdiagnosed.

Data from the study reveal that thyroid incidences increased from 5.0 cases per 100,000 people in 1975 to 14.6 per 100,000 in 2009, whereafter it plateaued until 2019 at 14.1 cases per 100,000 people. Furthermore, the absolute rate of metastasis between 1975 and 2019 remained stable at 0.4 cases per 100,000 people and 0.4 cases per 100,000 people, respectively. Absolute mortality similarly remained stable, with 0.5 deaths per 100,000 people reported in 1975 and 2019.

When adjusting for sex, the incidence rate for women in 1975 and its 2014 peak were 6.6 cases per 100,000 people and 22.2 cases per 100,000 people, respectively. For men, in 1975 and 2012, where it peaked, rates were 3.4 cases per 100,000 people and 8.1 cases per 100,000 people, respectively. Additionally, the metastasis rate for women was 0.4 cases per 100,000 people in both 1975 and 2019, and the mortality decreased from 0.6 deaths per 100,000 to 0.5 deaths per 100,000 people in respective years. For men, the metastasis rate was 0.3 cases per 100,000 people in 1975 and 2019, with a slight increase in mortality from 0.4 deaths per 100,000 people in 1975 to 0.5 deaths per 100,000 people in 2019.

For women and men, between 1975 and 2019, the net drift for thyroid cancer incidence was 3.56% (95% CI, 3.42%-3.71%) and 2.87% (95% CI, 2.69%-3.05%), respectively. When adjusting for age in women, the peak rates of local drift were observed in those 55 to 59 years at 4.03% (95% CI, 3.81%-4.26%). For men, those 70 to 74 years were observed to have the highest rates at 3.26% (95% CI, 2.86%-3.67%).

“Many studies have established that the incidence of thyroid cancer has dramatically increased for at least 4 decades, but the probability of dying of thyroid cancer has remained exactly the same,” study senior author Zachary Zumsteg, MD, associate professor of Radiation Oncology and Biomedical Sciences at Cedars-Sinai Cancer, said in a news release on the findings.² “This means we are diagnosing and treating many cancers that would do no harm despite recent efforts to reduce overdiagnosis.”

Investigators used the Surveillance, Epidemiology, and End Results (SEER) and National Center for Health Statistics databases to populate the study. A total of 91,968 patients, including 23,467 men (25.5%) and 68,501 (74.5%) women diagnosed with thyroid cancer with malignant histology were included using incidence data from the SEER-8 registry obtained between 1975 and 2019.

Age-period-cohort analyses were conducted to allow for the assessment of independent effects of the cohort, defined as year of birth, from the period, defined as year of diagnosis, on overall incidence trends. Additionally, birth cohorts were established based on the differences between year of diagnosis and year of birth.

Additional data reveal that increasing incidence of thyroid cancer for a given age group with subsequent birth cohorts was observed. Of note, from the 1920 baseline, the rate ratio for developing thyroid cancer increased by a factor of 11.72 (95% CI, 9.84-13.95) for women and 6.99 (95% CI, 5.44-8.98) for men in the most recent birth cohort, identified as 1990 to 1994. The period rate ratio revealed a sharp rise from 1975 to 2010, plateauing during the 2010 to 2014 and 2015 to 2019 time periods.

References

1. Chen MM, Luu M, Sacks WL, et al. Trends in incidence, metastasis, and mortality from thyroid cancer in the USA from 1975 to 2019: a population-based study of age, period, and cohort effects. Lancet Diabetes Endocrinol. Published online February 5, 2025. doi:10.1016/ S2213-8587(24)00310-3
2. Study: thyroid cancer still overdiagnosed. News release. Cedars-Sinai. February 5, 2025. Accessed February 7, 2025. https://tinyurl.com/478drjxz