ECE2017 Oral Communications Thyroid Cancer (5 abstracts)
1Asan Medical Center, Seoul, Republic of Korea; 2Dongnam Institute of Radiological & Medical Sciences Cancer Center, Busan, Republic of Korea.
Background: Unlike excellent prognosis of classical papillary thyroid carcinoma (cPTC), certain pathological subtypes of aggressive variants of PTC (AV-PTC) are considered to have poor clinical outcome. However, the evidence of unfavorable outcome of AV-PTC is not clear because previous studies did not control other confounding factors contributed to clinical outcomes.
Methods: This retrospective cohort study initially included 4339 patients with cPTC and 121 patients with AV-PTC including tall cell, columnar, hobnail, solid and diffuse sclerosing variants. Dynamic risk stratification (DRS) and recurrence free survival (RFS) between the two groups were compared after two-to-one individual risk factor matching by age, sex, tumor size, and initial surgical extent.
Outcome: AV-PTC was associated with larger tumor size (P<0.001) and higher rates of cervical lymph node (LN) metastasis (P<0.001) compared to cPTC. A total of 121 patients with AV-PTC and 242 patients with cPTC were evaluated after individual risk factor matching. There were no significant differences in the tumor size and cervical LN metastasis between the two groups after mating. When we compared the proportion of patients according to the DRS, there was no significant difference between patients with cPTC and those with AV-PTC (P=0.14). There was also no significant difference in RFS (hazard ratio [HR] 1.93, 95% confidence interval [CI] 0.68-5.47, P=0.23) between the two groups. In subgroup analysis including patients with tall cell, columnar, and hobnail variants of PTC, there were no significant differences in DRS (P=0.68) and RFS (HR 2.04, 95% CI 0.56-7.41, P=0.29) compared with matched patients with cPTC.
Conclusion: The clinical outcome of patients with AV-PTC was not different with those with cPTC when their other clinicopathological risk factors were similar. Therapeutic and follow-up strategies for PTC might not need to be modified according to presence of AV-PTCs.