Refining Outcome Prognostication After Initial Treatment of Differentiated Thyroid Cancer
Posted: Tuesday, October 20, 2020
The 2015 American Thyroid Association (ATA) guidelines described a risk-stratification system to estimate differentiated thyroid cancer prognosis. Stéphane Bardet, MD, of the François Baclesse Cancer Centre, Caen, France, and colleagues conducted a study to examine the correlation of postoperative persistent disease with the ATA risk-stratification system. They also sought to determine its impact on response to initial therapy and outcome. The results of this retrospective cohort study were published in BMC Cancer.
The investigators focused on 618 patients with differentiated thyroid cancer who were referred for postoperative radioiodine treatment. Using the 2015 ATA guidelines, patients were risk-stratified based on postoperative data. The investigators defined very small–volume persistent disease as the presence of abnormal foci on post-radioiodine scintigraphy with SPECT/CT or FDG PET/CT without identifiable lesions on anatomic imaging. The small-volume persistent disease was defined as lesions smaller than 10 mm, and large-volume persistent disease was defined as lesions at least 10 mm in size.
The persistent disease was observed in 17% of the study population. The percentages of large-volume persistent disease in low-, intermediate-, and high-risk patients were 18%, 56%, and 89%, respectively (P < .0001). At 9 to 12 months after initial therapy, there appeared to be a significant trend towards a decrease in excellent response rate from the very small– (71%), small- (20%) to large-volume (7%) persistent disease groups (P = .01). This also seemed to be true at the last follow-up visit (75%, 28%, and 16%, respectively; P = .04). The investigators identified four independent risk factors for indeterminate or incomplete response at last follow-up visit: age of at least 45 years; distant and/or thyroid bed disease; small- or large-volume tumor burden; and FDG-positive persistent disease.
“These findings confirm that tumor burden of persistent disease is a variable that might be taken into account to refine outcome prognostication,” the investigators concluded.
Disclosure: The study authors reported no conflicts of interest.