A group of researchers led by a physician from Memorial Sloan Kettering Cancer Center in New York City examined the natural history and growth kinetics of low-risk papillary thyroid cancer (PTC), defined as intrathyroidal tumors ≤1.5 cm in size.
Active surveillance of low-risk PTC is an alternative to surgical removal. However, outcomes have not been fully studied.
In addition, the kinetics (probability, rate, and magnitude) of PTC tumor growth in patients who do not undergo surgery and are followed-up long-term have not been well defined.
In this cohort study of 291 patients undergoing active surveillance for low-risk PTC, 219 (75.3%) were women and the mean age of the group was 52 years.
During a median active surveillance of 25 months, growth in tumor diameter of 3 mm or more was observed in 11 of 291 (3.8%) patients. No regional or distant metastases developed during active surveillance.
Both younger age at diagnosis and a higher risk category at presentation were independently associated with the likelihood of tumor growth. Of the tumors that grew, kinetics demonstrated a classic exponential growth pattern, with a median doubling time of 2.2 years.
The researchers concluded that tumor volume kinetics can inform the timing of surveillance imaging for PTC. Study findings are available here.