Low-Risk Papillary Thyroid Cancer

Sep 2, 2017
Findings Support Use of Active Surveillance for Low-Risk Papillary Thyroid Cancer

Multiple measurements of tumor volume among patients undergoing active surveillance for small, low-risk papillary thyroid cancer in the U.S. found that most cancers remained stable over several years of observation, with the use of serial measurements defining the rate of growth for tumors, which can inform the timing of surveillance or treatment for patients, according to a study published by JAMA Otolaryngology-Head & Neck Surgery.

With wider use of diagnostic and imaging technologies, many small, subclinical papillary thyroid cancers (PTCs) are now being detected. If never diagnosed and treated, most (estimated as 50 percent-90 percent) of these PTCs would not go onto cause symptoms or death. A more dynamic characterization of tumor growth based on 3-D volume measurements may allow for earlier determination of whether a PTC is stable or growing. R. Michael Tuttle, M.D., of the Memorial Sloan Kettering Cancer Center, New York, and colleagues examined tumor volume kinetics (probability, rate, and magnitude) in 291 patients undergoing active surveillance for low-risk PTCs (1.5 cm or less) in the United States, with serial tumor measurements via ultrasonography.

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 percent) patients, with a cumulative incidence of 2.5 percent (2 years) and 12.1 percent (5 years). No regional or distant metastases developed during active surveillance. In all cases, 3-dimensional measurements of tumor volume allowed for earlier identification of growth. An increase in tumor size was more likely in younger patients. The kinetics of PTC volume growth followed classic exponential growth patterns, indicating that growth can be accurately modeled.

Limitations of the study are noted in the article.

“As the number of small, incidentally detected PTCs continues to increase, new approaches are needed to avoid overtreatment of tumors that would otherwise remain indolent and asymptomatic while identifying the small percentage of such tumors that will continue to grow. Because PTCs appear to follow predictable growth kinetics under active surveillance, serial measurements of tumor volume hold significant promise in triaging patients to observation vs surgery. Additional studies will helpful to determine the clinical significance of mild growth in PTC diameter and volume and further refine the thresholds for intervention,” the authors write.