title: Radioactive iodine treatment for node negative papillary thyroid cancer with capsular invasion only: Results of a large retrospective study.
abstract: OBJECTIVE
  With thyroid carcinoma the decision to use radioactive iodine (RAI) ablation depends on the risk of poor outcomes. Although extrathyroid extension (ETE) is well known as a risk of poor outcomes for papillary thyroid carcinoma (PTC), the definition of minimal ETE is too broad, as it encompasses both microscopic invasion of the thyroid capsule (capsular invasion [CI]) and macroscopic invasion of the sternothyroid muscle.
  
  
  METHODS
  We conducted a retrospective study to analyze the prognostic benefit of RAI ablation according to the presence of CI in a consecutive series of patients with PTC between October 1997 and December 2008. We studied two groups of patients, including those who received RAI (group I, n = 121) and those who did not (group II, n = 108). During follow-up, we assessed the locoregional recurrence of all patients.
  
  
  RESULTS
  There were no statistically significant difference between the groups regarding locoregional recurrence at follow-up (13.2% for group I vs 9.3% for group II, P = 0.441). The association between RAI and locoregional recurrence in PTC patients with CI remained insignificant after adjusting for potential confounders, such as age, tumor size, sex, lymphatic invasion, vascular invasion and tumor multiplicity (P = 0.409, hazard ratio = 0.698, 95% confidence interval, 0.298-1.639).
  
  
  CONCLUSIONS
  This retrospective study suggests that RAI treatment is not associated with less locoregional recurrence in PTC patients who only demonstrate CI, although further prospective studies are required to confirm these findings.
authors.affiliation: Department of Surgery, The Catholic University of Korea St. Vincent's Hospital, Suwon, Kyounggi-do, Korea.
authors.forename: Ye-Won
authors.initials: YW
authors.lastname: Jeon
authors.affiliation: Department of Radiology, The Catholic University of Korea St. Vincent's Hospital, Suwon, Kyounggi-do, Korea.
authors.forename: Young-Ee
authors.initials: YE
authors.lastname: Ahn
authors.affiliation: Department of Radiology, The Catholic University of Korea St. Vincent's Hospital, Suwon, Kyounggi-do, Korea.
authors.forename: Won-Sang
authors.initials: WS
authors.lastname: Chung
authors.affiliation: Department of Pathology, The Catholic University of Korea St. Vincent's Hospital, Suwon, Kyounggi-do, Korea.
authors.forename: Hyun-Joo
authors.initials: HJ
authors.lastname: Choi
authors.affiliation: Department of Surgery, The Catholic University of Korea St. Vincent's Hospital, Suwon, Kyounggi-do, Korea.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Suh
mesh_terms: D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002277:Carcinoma / Q000532:radiotherapy*; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D007455:Iodine; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000532:radiotherapy*
chemical_list: D000970:Antineoplastic Agents; D007457:Iodine Radioisotopes; D007455:Iodine
keywords: capsular invasion; papillary thyroid carcinoma; radioactive iodine ablation; recurrence