Aggressive papillary thyroid carcinoma (PTC) incidence is rising at an even faster rate than that for well-differentiated papillary thyroid cancers, and outcomes vary markedly by histology type, US researchers say.

Their analysis of data on more than 5400 patients in two large US cancer databases, diagnosed between 2000 and 2016, shows that the incidence of the aggressive forms of the disease is rising by 9.1% per year.

In comparison, rates of well-differentiated PTC rose by 5.1%, while anaplastic PTC cases rose by just 1.9% over the same period, the authors write in JAMA Oncology.

While the rise in well-differentiated PTC has been attributed in part to incidental diagnosis, this is not likely to be the case for aggressive PTC, given the high degree of advanced, symptomatic disease in these subtypes, they caution.