title: Dynamic Risk Stratification in Patients with Differentiated Thyroid Cancer Treated Without Radioactive Iodine.
abstract: Although response to therapy assessment is a validated tool for dynamic risk stratification in patients with differentiated thyroid cancer (DTC) treated with total thyroidectomy (TT) and radioactive iodine therapy (RAI), it has not been well studied in patients treated with lobectomy or TT without RAI. Because these responses to therapy definitions are heavily dependent on serum thyroglobulin (Tg) levels, modifications of the original definitions were needed to appropriately classify patients treated without RAI.
  
  
  
  This study aimed to validate the response to therapy assessment in patients with DTC treated with lobectomy or TT without RAI.
  
  
  
  This was a retrospective study, which took place at a referral center.
  
  
  
  A total of 507 adults with DTC were treated with lobectomy (n = 187) or TT (n = 320) without RAI. They had a median age of 43.7 y, 88% were female, 85.4% had low risk, and 14.6% intermediate risk.
  
  
  
  Main outcome measured was recurrent/persistent structural evidence of disease (SED) during a median followup period of 100.5 months (24-510).
  
  
  
  Recurrent/persistent SED was observed in 0% of the patients with excellent response to therapy (nonstimulated Tg for TT < 0.2 ng/mL and for lobectomy < 30 ng/mL, undetectable Tg antibodies [TgAb] and negative imaging; n = 326); 1.3% with indeterminate response (nonstimulated Tg for TT 0.2-5 ng/mL, stable or declining TgAb and/or nonspecific imaging findings; n = 2/152); 31.6% of the patients with biochemical incomplete response (nonstimulated Tg for TT > 5 ng/mL and for lobectomy > 30 ng/mL and/or increasing Tg with similar TSH levels and/or increasing TgAb and negative imaging; n = 6/19) and all (100%) patients with structural incomplete response (n = 10/10) (P < .0001). Initial American Thyroid Association risk estimates were significantly modified based on response to therapy assessment.
  
  
  
  Our data validate the newly proposed response to therapy assessment in patients with DTC treated with lobectomy or TT without RAI as an effective tool to modify initial risk estimates of recurrent/persistent SED and better tailor followup and future therapeutic approaches. This study provides further evidence to support a selective use of RAI in DTC.
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Denise P
authors.initials: DP
authors.lastname: Momesso
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Vaisman
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Samantha P
authors.initials: SP
authors.lastname: Yang
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Bulzico
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Rossana
authors.initials: R
authors.lastname: Corbo
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: Mario
authors.initials: M
authors.lastname: Vaisman
authors.affiliation: Endocrinology Service (D.P.M., F.V., D.A.B., R.C., M.V.), Universidade Federal do Rio de Janeiro and Instituto Nacional do Cancer, Rio de Janeiro 21941-902, Brazil; and Department of Endocrinology (S.P.Y., R.M.T.), Memorial Sloan Kettering Cancer Center, New York, New York 10065.
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000601:surgery; D013965:Thyroidectomy; D016896:Treatment Outcome; D055815:Young Adult