LOWER RATES OF RESIDUAL/RECURRENT DISEASE IN PATIENTS WITH INCIDENTALLY DISCOVERED THYROID CARCINOMA.

OBJECTIVE: Incidentally discovered thyroid cancers (IDTCs) have contributed to the rapid rise in thyroid cancer incidence over the past 20 years. Since death rates from thyroid cancer are not increasing, we hypothesized that IDTCs are less aggressive compared to clinically apparent thyroid cancer (CATC).

METHODS: A retrospective study of patients and tumor characteristics of IDTCs and their rates of residual/recurrent (R/R) disease were determined at a median follow-up of 27 months in the setting of a large academic medical center. Patient analysis groups (IDTC [n = 46] and CATC [n = 126]) were based upon how the cancer was initially discovered. Patients were followed clinically and by biochemical testing and ultrasonography. We also compared time to progression between these groups.

RESULTS: Patients in the two groups had similar demographic and tumor characteristics. At the close of the study, R/R status in the IDTC group was 6.7%, compared to 20.8% in the CATC group (P = .04). Of the 28 individuals in our overall cohort who had R/R disease, 3 were from the IDTC group and 25 were from the CATC group (P = .04). All three of the IDTC recurrences occurred within the first 6 months of follow-up. Using Kaplan-Meier analysis, there was a nonsignificant trend for longer progression-free survival in the IDTC group (P = .08).

CONCLUSION: Compared to CATC patients, IDTC patients have a significantly less aggressive course and a trend toward longer progression-free survival. If confirmed by further studies, it may be reasonable to subject them to less intense surveillance and more conservative therapeutic approaches.

ABBREVIATIONS: CATC = clinically apparent thyroid cancers CT = computed tomography HMH = Houston Methodist Hospital IDTC = incidentally discovered thyroid cancer MRI = magnetic resonance imaging PET = positron emission tomography PTMC = papillary thyroid microcarcinoma R/R = residual/recurrent RRA = radioiodine remnant ablation Tg = thyroglobulin TgAb = anti-thyroglobulin antibody TSH = thyroid-stimulating hormone US = ultrasonography.