Abstract
Background
According to the 8th edition American Joint Committee on Cancer staging system, extrathyroidal extension (ETE) and primary tumor size remain the principle determinants of T stage. However, impact of gross ETE into strap muscles on survival remains controversial.
Patients and Methods
A retrospective review of 2084 patients with ≤ 4 cm nonmetastatic differentiated thyroid cancer who underwent surgery between 2000 and 2015 was conducted. Patients were divided into three groups according to degree of ETE: no ETE (group 1), ETE into perithyroidal soft tissue (group 2), and gross ETE into strap muscle (group 3). Survivals were analyzed using Kaplan–Meier method and compared using log-rank test. Factors predictive of survival were analyzed using Cox proportional hazard model.
Results
Ten-year disease-free survival (DFS) of patients in groups 1–3 was 90, 82, and 83%, respectively (p = 0.003). On multivariate analysis, age ≥ 55 years, male sex, and pathologic N1b category predicted significantly worse DFS, while ETE into perithyroidal soft tissue or gross strap muscle invasion did not predict worse DFS. Overall survival (p = 0.957) and disease-specific survival (p =0.910) were not significantly different between the three groups. There was a statistically significant difference in locoregional recurrence-free survival between groups 1 and 2 [HR 2.02, 95% CI 1.06–3.94].
Conclusion
Gross strap muscle invasion may not be an important survival prognostic factor for staging purposes. Although both gross strap muscle invasion and perithyroidal soft tissue extension may be predictive for locoregional recurrence, the distinction between them may not be as important for postoperative risk stratification.
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References
Sherman SI. Thyroid carcinoma. Lancet. 2003;361(9356):501–511.
Ganly I, Nixon IJ, Wang LY, et al. Survival from differentiated thyroid cancer: what has age got to do with it? Thyroid. 2015;25(10):1106–1114.
Hay ID, Grant CS, Taylor WF, McConahey WM. Ipsilateral lobectomy versus bilateral lobar resection in papillary thyroid carcinoma: a retrospective analysis of surgical outcome using a novel prognostic scoring system. Surgery. 1987;102(6):1088–1095.
Cady B, Rossi R. An expanded view of risk-group definition in differentiated thyroid carcinoma. Surgery. 1988;104(6):947–953.
Byar DP, Green SB, Dor P, et al. A prognostic index for thyroid carcinoma. A study of the E.O.R.T.C. Thyroid Cancer Cooperative Group. Eur J Cancer. 1979;15(8):1033–1041.
Edge SB, American Joint Committee on Cancer. AJCC cancer staging manual. 7th ed. New York: Springer; 2010.
Amin M, Edge S. AJCC cancer staging manual. 8th ed. Cham: Springer; 2017.
Haugen BR, Alexander EK, Bible KC, et al. 2015. American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid. 2016;26(1):1–133.
Hay ID. Papillary thyroid carcinoma. Endocrinol Metab Clin North Am. 1990;19(3):545–576.
Hay ID, Bergstralh EJ, Goellner JR, Ebersold JR, Grant CS. Predicting outcome in papillary thyroid carcinoma: development of a reliable prognostic scoring system in a cohort of 1779 patients surgically treated at one institution during 1940 through 1989. Surgery. 1993;114(6):1050–1057. (Discussion 1057–1058).
Shaha AR, Loree TR, Shah JP. Intermediate-risk group for differentiated carcinoma of thyroid. Surgery. 1994;116(6):1036–1040. (Discussion 1040–1031).
Cody HS, 3rd, Shah JP. Locally invasive, well-differentiated thyroid cancer. 22 years’ experience at Memorial Sloan-Kettering Cancer Center. Am J Surg. 1981;142(4):480–483.
Hay ID, Johnson TR, Thompson GB, Sebo TJ, Reinalda MS. Minimal extrathyroid extension in papillary thyroid carcinoma does not result in increased rates of either cause-specific mortality or postoperative tumor recurrence. Surgery. 2016;159(1):11–19.
Ito Y, Tomoda C, Uruno T, et al. Prognostic significance of extrathyroid extension of papillary thyroid carcinoma: massive but not minimal extension affects the relapse-free survival. World J Surg. 2006;30(5):780–786.
Arora N, Turbendian HK, Scognamiglio T, et al. Extrathyroidal extension is not all equal: Implications of macroscopic versus microscopic extent in papillary thyroid carcinoma. Surgery. 2008;144(6):942–947. (Discussion 947–948).
Nixon IJ, Ganly I, Patel S, et al. The impact of microscopic extrathyroid extension on outcome in patients with clinical T1 and T2 well-differentiated thyroid cancer. Surgery. 2011;150(6):1242–1249.
Moon HJ, Kim EK, Chung WY, Yoon JH, Kwak JY. Minimal extrathyroidal extension in patients with papillary thyroid microcarcinoma: is it a real prognostic factor? Ann Surg Oncol. 2011;18(7):1916–1923.
Woo CG, Sung CO, Choi YM, et al. Clinicopathological significance of minimal extrathyroid extension in solitary papillary thyroid carcinomas. Ann Surg Oncol. 2015;22 Suppl 3:S728–S733.
Park JS, Chang JW, Liu L, Jung SN, Koo BS. Clinical implications of microscopic extrathyroidal extension in patients with papillary thyroid carcinoma. Oral Oncol. 2017;72:183–187.
Ito Y, Tomoda C, Uruno T, et al. Minimal extrathyroid extension does not affect the relapse-free survival of patients with papillary thyroid carcinoma measuring 4 cm or less over the age of 45 years. Surg Today. 2006;36(1):12–18.
Jin BJ, Kim MK, Ji YB, Song CM, Park JH, Tae K. Characteristics and significance of minimal and maximal extrathyroidal extension in papillary thyroid carcinoma. Oral Oncol. 2015;51(8):759–763.
Al-Qurayshi Z, Shama MA, Randolph GW, Kandil E. Minimal extrathyroidal extension does not affect survival of well-differentiated thyroid cancer. Endocr Relat Cancer. 2017;24(5):221–226.
Youngwirth LM, Adam MA, Scheri RP, Roman SA, Sosa JA. Extrathyroidal extension is associated with compromised survival in patients with thyroid cancer. Thyroid. 2017;27(5):626–631.
Greene FL, American Joint Committee on Cancer, American Cancer Society. AJCC Cancer Staging Manual. 6th ed. New York: Springer; 2002.
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Amit, M., Boonsripitayanon, M., Goepfert, R.P. et al. Extrathyroidal Extension: Does Strap Muscle Invasion Alone Influence Recurrence and Survival in Patients with Differentiated Thyroid Cancer?. Ann Surg Oncol 25, 3380–3388 (2018). https://doi.org/10.1245/s10434-018-6563-x
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DOI: https://doi.org/10.1245/s10434-018-6563-x