Patients with intermediate or high-risk differentiated thyroid cancer may not benefit from thyrotropin suppression with levothyroxine, according to results of a retrospective study published in JAMA Network Open.
“We found that thyroid suppression was not associated with improved PFS and OS [in patients with intermediate or high-risk differentiated thyroid cancer],” Joanna Klubo-Gwiezdzinska, MD, PhD, MHSc, assistant clinical investigator and assistant professor in the metabolic disease branch of the National Institute of Diabetes and Digestive and Kidney Diseases/NIH, and colleagues wrote. “In fact, patients with suppressed thyrotropin levels who survived 3 years were characterized by shorter OS than patients whose levels were not suppressed.”
Conflicting evidence guides the use of thyrotropin suppression — often referred to as thyroid-stimulating hormone — with levothyroxine to reduce risk for progression and death in intermediate- and high-risk differentiated thyroid cancer.
Klubo-Gwiezdzinska and colleagues analyzed 867 patients (mean age, 48.5 years; 64.2% women) with differentiated thyroid cancer treated with total thyroidectomy and a median cumulative dose of 151 mCi (range, 30-1,600) radioactive iodine.
OS and PFS served as the primary endpoints of the study.
Within mean follow-up of 7.2 years, 293 patients (33.8%) experienced disease progression and 34 (3.9%) died. This left the study underpowered in death events.
Results showed no association between thyrotropin suppression and improved PFS at 1.5 years, 3 years and 5 years.
After 1.5 years, older age (HR = 1.06; 95% CI, 1.03-1.08), lateral neck lymph node metastases (HR = 4.64; 95% CI, 2-10.7) and distant metastases (HR = 7.54; 95% CI, 3.46-16.5) all appeared independently associated with subsequent time to progression. This trend continued at 3 years (older age, HR = 1.05; 95% CI, 95% CI, 1.01-1.08; lateral neck lymph node metastases, HR = 4.02; 95% CI, 1.56-10.4; distant metastases, HR = 7.1; 95% CI, 2.77-18.2).
At 5 years, patients with lateral neck lymph node metastases had shorter PFS (HR = 3.7; 95% CI, 1.16-11.9) and poorly differentiated histology (HR = 71.8; 95% CI, 9.8-526.).
A lack of factors associated with OS and the study’s retrospective design served as limitations.
“Thyrotropin suppression was not associated with improved PFS in [American Thyroid Association] intermediate- and high-risk differentiated thyroid cancer,” Klubo-Gwiezdzinska and colleagues wrote. “A large prospective trial randomizing patients with intermediate and high-risk differentiated thyroid cancer ... is necessary to formulate an unbiased recommendation regarding the optimal thyrotropin goal.” – by John DeRosier
Disclosures: Klubo-Gwiezdzinska reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.