Poorly Differentiated Thyroid Carcinoma Presenting with Gross Extrathyroidal Extension: 1986–2009 Memorial Sloan-Kettering Cancer Center Experience

Abstract

To describe the outcome of patients with poorly differentiated thyroid cancer (PDTC) presenting with gross extrathyroidal extension (ETE). After obtaining Institutional Review Board approval, we performed a retrospective review of a consecutive series of thyroid cancer patients treated by primary surgical resection with or without adjuvant therapy at Memorial Sloan-Kettering Cancer Center from 1986 to 2009. Out of 91 PDTC patients, 27 (30%) had gross ETE (T4a), and they formed the basis of our study. Of 27 patients, 52% were women. The median age was 70 years (range 27-87 years). Ten patients (37%) presented with distant metastases; four to bone, three to lung, and three to both bone and lung. All patients had extended total thyroidectomy, except two who had subtotal thyroidectomy. Twenty patients (74%) had central compartment neck dissection and 11 also had lateral neck dissection. Four patients had pN0, six (30%) pN1a, and 10 (50%) pN1b neck disease. Twenty-one patients (77%) had adjuvant therapy: 15 (55%) radioactive iodine (RAI) only, three (11%) postoperative external beam radiation (EBRT) only, and three (11%) had both RAI and EBRT. Overall survival (OS), disease-specific survival (DSS), local recurrence-free survival (LRFS), and regional recurrence-free survival (RRFS) were calculated by the Kaplan Meier method. The median follow-up time was 57 months (range 1-197 months). The 5 year OS and DSS were 47% and 49%, respectively. This poor outcome was due to distant metastatic disease; 10 patients had distant metastases at presentation and a further six developed distant metastases during follow-up. Locoregional control was good with 5-year LRFS and RRFS of 70% and 62%, respectively. Overall, eight patients (30%) had recurrences: two had distant alone, two regional, two regional and distant, one local and distant, and one had local, regional, and distant recurrence. Aggressive surgery in patients with PDTC showing gross ETE resulted in satisfactory locoregional control. Due to the small proportion of patients who received EBRT (22%), it is not possible to analyze its benefit on locoregional control. Of significance is the observation that the majority of patients (60%) who presented with or subsequently developed distant metastases eventually died of distant disease. New systemic therapies to target distant metastatic disease are required for improvements in outcome.