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Optimal cut‐off age in the TNM Staging system of differentiated thyroid cancer: is 55 years better than 45 years?
Author(s) -
Kim Mijin,
Kim Young Nam,
Kim Won Gu,
Park Suyeon,
Kwon Hyemi,
Jeon Min Ji,
Ahn Hyeon Seon,
Jung SinHo,
Kim Sun Wook,
Kim Won Bae,
Chung Jae Hoon,
Shong Young Kee,
Kim Tae Hyuk,
Kim Tae Yong
Publication year - 2017
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/cen.13254
Subject(s) - medicine , thyroid cancer , receiver operating characteristic , stage (stratigraphy) , cohort , thyroid , oncology , urology , surgery , paleontology , biology
Summary Objective Age >45 years is included as a variable in the tumor, node, metastases (TNM) staging of differentiated thyroid cancer ( DTC ), but a higher cut‐off value has been suggested to be more clinically relevant and prevent over‐staging. We evaluated the optimal age cut‐off to predict disease‐specific survival ( DSS ) in patients with DTC . Design and Patients This cohort study included 6333 patients with DTC who underwent thyroid surgery at two tertiary referral centres between 1996 and 2005. The optimal age cut‐off value between 45 and 65 years for prediction of DSS was assessed. The proportion of variation explained ( PVE ) and Harrell's c‐index was calculated to compare the predictability of each model. Results The median age of patients was 46·0 years ( IQR 37·8–54·6), and 5498 (87%) were female. Median follow‐up period was 10·0 years, and 10‐year DSS rate was 98%. Using TNM staging with 45 years as the cut‐off ( TNM 45), 10‐year DSS rates of stage I– IV were 99·4%, 96·1%, 97·7% and 85·9%, respectively ( PVE = 3·0%, Harrell's c‐index = 0·693); and using 55 years as the cut‐off ( TNM 55), 99·4%, 92·2%, 95·3% and 79·7%, respectively ( PVE = 4·3%, Harrell's c‐index = 0·776). On receiver operating characteristic curve analysis, the optimal age cut‐off for prediction of DSS was 55·4 years (area under the curve = 0·837, P < 0·001). About 20% of patients were down‐staged to stage I using TNM 55 compared to that using TNM 45. Conclusions The cut‐off age of 55 years was more appropriate for TNM staging to achieve better predictability for DSS in patients with DTC . This change would prevent over‐staging in low‐risk patients and prevent over‐aggressive treatment.