Papillary thyroid carcinoma managed at the Mayo Clinic during six decades (1940-1999): Temporal trends in initial therapy and long-term outcome in 2444 consecutively treated patients

It is uncertain whether more extensive primary surgery and increasing use of radioiodine remnant ablation (RRA) for papillary thyroid carcinoma (PTC) have resulted in improved rates of cause-specific mortality (CSM) and tumor recurrence (TR). Details of the initial presentation, therapy, and outcome of 2444 PTC patients consecutively treated during 1940-1999 were recorded in a computerized database. Patients were followed for more than 43,000 patient-years. The 25-year rates for CSM and TR were 5% and 14%, respectively. Temporal trends were analyzed for six decades. During the six decades, the proportion with initial MACIS (distant Metastasis, patient Age, Completeness of resection, local Invasion, and tumor Size) scores < 6 were 77%, 82%, 84%, 86%, 85%, and 82%, respectively (p = 0.06). Lobectomy accounted for 70% of initial procedures during 1940-1949 and 22% during 1950-1959; during 1960-1999 bilateral lobar resection (BLR) accounted for 91% of surgeries (p < 0.001). RRA after BLR was performed during 1950-1969 in 3% but increased to 18%, 57%, and 46% in successive decades (p < 0.001). The 40-year rates for CSM and TR during 1940-1949 were significantly higher (p = 0.002) than during 1950-1999. During the last 50 years the 10-year CSM and TR rates for the 2286 cases did not significantly change with successive decades. Moreover, the 10-year rates for CSM and TR were not significantly improved during the last five decades of the study, either for the 1917 MACIS < 6 patients or the 369 MACIS ≥ 6 patients. Increasing use of RRA has not apparently improved the already excellent outcome, achieved before 1970, in low risk (MACIS < 6) PTC patients managed by near-total thyroidectomy and conservative nodal excision.