title: Microscopic Positive Margins in Differentiated Thyroid Cancer Is Not an Independent Predictor of Local Failure.
abstract: BACKGROUND
  In contrast to other head and neck cancers, the impact of histological thyroid specimen margin status in differentiated thyroid cancer (DTC) is not well understood. The aim of this study was to investigate the prognostic value of margin status on local recurrence in DTC.
  
  
  METHODS
  The records of 3664 consecutive patients treated surgically for DTC between 1986 and 2010 were identified from an institutional database. Patients with less than total thyroidectomy, unresectable or gross residual disease, or M1 disease at presentation and those with unknown pathological margin status were excluded from analysis. In total, 2616 patients were included in the study; 2348 patients (90%) had negative margins and 268 patients (10%) had positive margins. Microscopic positive margin status was defined as tumor present at the specimen's edge on pathological analysis. Patient, tumor, and treatment characteristics were compared by Pearson's chi-squared test. Local recurrence free survival (LRFS) was calculated for each group using the Kaplan Meier method.
  
  
  RESULTS
  The median age of the cohort was 48 years (range 7-91 years) and the median follow-up was 50 months (range 1-330 months). Age, sex, and histology types were similar between groups. As expected, patients who had positive margins were more likely to have larger tumors (p<0.001), extrathyroidal extension (ETE) (p<0.001), multicentric disease (p<0.001), or nodal disease (p<0.001) and were more likely to receive adjuvant radioactive iodine therapy (p<0.001) as well as external beam radiotherapy (p<0.001). The LRFS at 5 years for patients with positive margins status was slightly poorer compared with patients with negative margins (98.9% vs. 99.5%, p=0.018). Twelve patients developed local recurrence-8/2348 (0.34%) patients with negative margins and 4/263 (1.52%) patients with positive margins. Univariate predictors of LRFS were sex (p=0.006), gross ETE (<0.001), and positive margins (p=0.018). However, when controlling for presence of gross ETE on multivariate analysis, microscopic positive margin status was not an independent predictor of LRFS (p=0.193).
  
  
  CONCLUSIONS
  Patients with resectable, M0 disease that undergo total thyroidectomy have an excellent five year LRFS of 99.4%. Microscopic positive margin status was not a significant predictor for local failure after adjusting for ETE or pathological tumor (pT) stage.
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.|2 Department of Pathology, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Laura Y
authors.initials: LY
authors.lastname: Wang
authors.affiliation: 2 Department of Pathology, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Ronald
authors.initials: R
authors.lastname: Ghossein
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Frank L
authors.initials: FL
authors.lastname: Palmer
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Iain J
authors.initials: IJ
authors.lastname: Nixon
authors.affiliation: 3 Department of Medicine, Endocrine Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Ashok R
authors.initials: AR
authors.lastname: Shaha
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Jatin P
authors.initials: JP
authors.lastname: Shah
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Snehal G
authors.initials: SG
authors.lastname: Patel
authors.affiliation: 1 Department of Surgery, Head and Neck Service, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Ian
authors.initials: I
authors.lastname: Ganly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000601:surgery; D018365:Neoplasm, Residual; D011379:Prognosis; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000601:surgery*; D013965:Thyroidectomy / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes