ORIGINAL ARTICLE INFLUENCE OF AGE AND PRIMARY TUMOR SIZE ON THE RISK FOR RESIDUAL/RECURRENT WELL-DIFFERENTIATED THYROID CARCINOMA Steven Orlov, BSc, 1 David Orlov, HBSc, 1 Michael Shaytzag, HBSc, 1 Mark Dowar, HBSc, 1 Vafa Tabatabaie, MD, 1 Philip Dwek, HBSc, 1 Jonathan Yip, HBSc, 1 Cindy Hu, BSc, 1 Jeremy L. Freeman, MD, FRCSC, 2 Paul G. Walfish, MD, FRCPC 1,2 1 Medicine/Endocrine Division, Mount Sinai Hospital, University of Toronto Medical School, Toronto, Ontario, Canada. E-mail: walfish@mshri.on.ca 2 Department of Otolaryngology, Mount Sinai Hospital, University of Toronto Medical School, Toronto, Ontario, Canada Accepted 5 September 2008 Published online 3 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/hed.21020 Abstract: Background. Though age and primary tumor size predict cancer-specific survival in well-differentiated thyroid carcinoma (WDTC), their influence on residual/recurrent dis- ease has not been elucidated. Methods. In a retrospective study, residual/recurrent dis- ease was defined by the surrogate outcome of positive (2 lg/L) follow-up stimulated thyroglobulin after surgery and radi- oactive remnant ablation. Age, primary tumor size, and clinical staging systems were examined in the context of stimulated thyroglobulin outcome. Results. A total of 246 patients were followed up for a mean of 5.8 years. No significant difference in age (t(239) ¼ 0.61, p > .05) or tumor size (t(237) ¼ 0.16, p > .05) was found among patients with positive follow-up stimulated thyroglobulin compared with those with negative results. pTNM staging failed to demonstrate significant, stage-dependent increase in the percentage of patients with positive stimulated thyroglobu- lin, v 2 (2, N ¼ 229) ¼ 0.17, p > .05, unlike staging based solely on surgical pathology, v 2 (2, N ¼ 241) ¼ 34.97, p < .001. Conclusion. Age, primary tumor size, and pTNM staging do not predict risk for residual/recurrent WDTC, whereas extra- thyroidal extension at initial surgery is predictive. V V C 2009 Wiley Periodicals, Inc. Head Neck 31: 782–788, 2009 Keywords: thyroid carcinoma; patient age; primary tumor size; clinical predictors; pTNM staging; DeGroot staging An estimated 33,000 new cases of thyroid can- cer are expected in the United States in 2007 1 and this incidence is on the rise. 2 The majority of these malignancies are of papillary and follic- ular histopathology (well-differentiated thyroid carcinoma [WDTC]). 2–5 Although the prognosis for patients with thyroid cancer is good, with 5- and 10-year survival rates of 90% to 95%, 6–9 patients should continue to be monitored for re- sidual/recurrent disease which may still arise in cases considered at low risk of WDTC-related death. 10 Correspondence to: P. G. Walfish Contract grant sponsors: Joseph and Mildred Sonshine Family Centre for Head and Neck Diseases at Mount Sinai Hospital; Temmy Latner/ Dynacare Family Foundation; Julius Kuhl Family Foundation. This work was presented in part at the scientific program of ENDO ’07 Annual Meeting of the Endocrine Society, Toronto, Ontario, June 4, 2007 (Poster number: P3-602). V V C 2009 Wiley Periodicals, Inc. 782 Predictors for Recurrent Well-Differentiated Thyroid Carcinoma HEAD & NECK—DOI 10.1002/hed June 2009