19th January 2018,
Miriam Karalus, Jade AU Tamatea, Helen M Conaglen, Michael Dray, Goswin Y Meyer-Rochow, John V Conaglen, Marianne S Elston
Multinodular goitre (MNG) is common particularly in iodine-deficient regions.1 Animal studies demonstrate an increased proliferative rate of thyroid follicular cells in iodine deficiency, suggesting that low iodine intake may promote…
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In this paper we assessed the rates of thyroid cancer identified by the pathologist after surgical removal of the thyroid gland when cancer was not suspected prior to surgery. Removal of the thyroid was performed for a reason other than the suspicion of cancer such as pressure symptoms from a large gland (goitre) or overactivity of the gland. Of the group with normal thyroid hormone levels, 8% had an incidental thyroid cancer and of those with an overactive thyroid gland, 10% of patients has a thyroid cancer identified on routine pathological assessment of the specimen. Most of these incidental cancers were small and of a type which would be expected to be unlikely to alter survival even if diagnosis had been delayed.
Previously the risk of concomitant thyroid cancer in multinodular goitre (MNG) has been reported as approximately 4%. Cancer risk in toxic MNG was often considered lower than for non-toxic MNG, due to a possible protective effect of TSH suppression. However, recent American data suggest an approximately 18% risk of occult malignancy in both toxic and non-toxic MNG.
To assess malignancy risk in a New Zealand population undergoing thyroidectomy for MNG.
Single-centre study of patients undergoing thyroidectomy for MNG from 1 December 2006 to 30 November 2016.
Six hundred and two patients underwent surgery for MNG (448 non-toxic and 154 toxic). Of these, 95/602 (16%) had thyroid cancer. After excluding patients operated for preoperative suspicion for cancer, 30/401 (8%) patients with non-toxic MNG and 15/151 (10%) with toxic MNG had unsuspected or occult thyroid cancer (p=0.358). Patients with toxic MNG were less likely to undergo preoperative fine needle aspiration than those with non-toxic MNG (34% vs 52%, respectively p=0.0001). Two-thirds of unsuspected thyroid cancers were incidental micropapillary carcinomas and unlikely to alter survival irrespective of therapy.
Malignancy rates in MNG are higher than historically reported, although most unsuspected cancers are unlikely to alter mortality even if diagnosis is delayed.
- Carle A, Krejbjerg A, Laurberg P. Epidemiology of nodular goitre. Influence of iodine intake. Best Pract Res Clin Endocrinol Metab. 2014; 28:465–79.
- Boltze C, Brabant G, Dralle H, et al. Radiation-induced thyroid carcinogenesis as a function of time and dietary iodine supply: an in vivo model of tumorigenesis in the rat. Endocrinology. 2002; 143:2584–92.
- Zimmermann MB, Galetti V. Iodine intake as a risk factor for thyroid cancer: a comprehensive review of animal and human studies. Thyroid research. 2015; 8:8.
- Hercus CE, Benson WN, Carter CL. Endemic Goitre in New Zealand, and its Relation to the Soil-iodine: Studies from the University of Otago, New Zealand. The Journal of hygiene. 1925; 24:321–402 3.
- Jones E, McLean R, Davies B, et al. Adequate Iodine Status in New Zealand School Children Post-Fortification of Bread with Iodised Salt. Nutrients. 2016; 8:298.
- Kang AS, Grant CS, Thompson GB, van Heerden JA. Current treatment of nodular goiter with hyperthyroidism (Plummer’s disease): surgery versus radioiodine. Surgery. 2002; 132:916–23; discussion 23.
- Smith JJ, Chen X, Schneider DF, et al. Cancer after thyroidectomy: a multi-institutional experience with 1,523 patients. Journal of the American College of Surgeons. 2013; 216:571–7; discussion 7–9.
- Smith JJ, Chen X, Schneider DF, et al. Toxic nodular goiter and cancer: a compelling case for thyroidectomy. Ann Surg Oncol. 2013; 20:1336–40.
- Preece J, Grodski S, Yeung M, et al. Thyrotoxicosis does not protect against incidental papillary thyroid cancer. Surgery. 2014; 156:1153–6.
- Negro R, Valcavi R, Toulis KA. Incidental thyroid cancer in toxic and nontoxic goiter: Is TSH associated with malignancy rate? Results of a meta-analysis. Endocr Pract. 2013; 19:212–8.
- Cutfield RG, Croxson MS. A clinico-pathological study of 100 patients with solitary ‘cold’ thyroid nodules. N Z Med J. 1981; 93:331–3.
- Tamatea JA, Tu’akoi K, Conaglen JV, et al. Thyroid cancer in Graves’ disease: is surgery the best treatment for Graves’ disease? ANZ J Surg. 2014 Apr;84:231–4.
- Ito Y, Uruno T, Nakano K, et al. An observation trial without surgical treatment in patients with papillary microcarcinoma of the thyroid. Thyroid. 2003; 13:381–7.
- Hay ID, Hutchinson ME, Gonzalez-Losada T, et al. Papillary thyroid microcarcinoma: a study of 900 cases observed in a 60-year period. Surgery. 2008; 144:980–7; discussion 7–8.
- Ito Y, Miyauchi A, Inoue H, et al. An observational trial for papillary thyroid microcarcinoma in Japanese patients. World J Surg. 2010; 34:28–35.
- Grodski S, Brown T, Sidhu S, et al. Increasing incidence of thyroid cancer is due to increased pathologic detection. Surgery. 2008; 144:1038–43; discussion 43.
- Iodine Global Network. Iodine status by region [Available from: http://www.ign.org/p142000957.html] Accessed 20 June 2017.
- Royal College of Pathologists of Australasia. Thyroid [Available from: http://www.rcpa.edu.au/Library/Practising-Pathology/Macroscopic-Cut-Up/Specimen/Endocrine/Thyroid] Accessed 20 June 2017.
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