Elsevier

Endocrine Practice

Volume 17, Issue 2, March–April 2011, Pages 201-209
Endocrine Practice

Original Article
Autoimmune Thyroid Disease: A Risk Factor for Thyroid Cancer

https://doi.org/10.4158/EP10123.ORGet rights and content

ABSTRACT

Objective

To examine the relationship between clinical markers of autoimmune thyroid disease and the risk of thyroid cancer in patients with thyroid nodules.

Methods

A retrospective cohort analysis was performed in a single clinical practice. In 2, 500 consecutive patients, fine-needle aspiration biopsy (FNAB) was performed on all 3, 658 ultrasonography-positive thyroid nodules that were ≥ 1.0 cm in diameter or ≥ 0.5 cm in diameter with ultrasound features suspicious for thyroid cancer. Serum concentrations of thyroglobulin antibodies (TgAb), thyroid peroxidase antibodies, and thyroid-stimulating hormone were measured before FNAB. Diagnosis of thyroid cancer was based on pathologic analysis of thyroidectomy tissue. Associations of thyroid cancer with the independent variables were determined by multivariate logistic regression analysis and reported as the adjusted odds ratio (OR) with the 95% confidence interval (CI).

Results

There were 202 patients with malignant thyroid nodules, 51 patients with microscopic unsuspected thyroid cancer distal to the nodule under investigation (found at thyroidectomy), and 2, 247 patients with benign thyroid nodules. To evaluate the association of clinical markers for autoimmune thyroid disease with thyroid cancer, we included all 253 patients with thyroid cancer in the malignant cohort. Thyroid cancer was associated with elevated levels of TgAb (OR = 1.57; CI = 1.11 to 2.23) and age < 55 years (OR = 2.01; CI = 1.45 to 2.78), and a strong trend was demonstrated for association with male sex (OR = 1.45; CI = 0.99 to 2.12). Thyroid cancer was not associated with elevated levels of thyroid peroxidase antibodies.

Conclusion

In patients who have thyroid nodules with indications for FNAB, elevated levels of TgAb are associated with thyroid cancer. (Endocr Pract. 2011;17: 201-209)

Section snippets

INTRODUCTION

Chronic tissue inflammation is associated with an increased risk of tissue-specific malignant disease (1, 2). Multiple mechanisms may contribute to inflammation-induced tumorigenesis (1., 2., 3.).

Autoimmune thyroid diseases (Hashimoto disease and Graves disease) cause chronic thyroid inflammation, and their prevalence in the general population is about 10% (4). The association between autoimmune thyroid diseases and the risk of thyroid carcinoma is controversial. Some retrospective pathology

Study Subjects

The patient population was 2, 500 consecutive patients with at least one ultrasonography-confirmed thyroid nodule with an indication for FNAB, as described in the subsequent material. All patients underwent assessment in the office of a single endocrinologist in North Carolina from January 1, 2004, to October 1, 2009. The Institutional Review Board of the New Hanover Regional Medical Center, Wilmington, North Carolina, approved this study.

Investigations

All patients with a known or suspected thyroid disorder

RESULTS

In a total of 2, 500 patients, there were 3, 658 thyroid nodules that met the criteria for FNAB, and FNAB was performed on all 3, 658 nodules. A total of 550 patients underwent thyroidectomy, 253 of whom had thyroid cancer. Thyroid cancer was found in the nodule (or nodules) under investigation in 202 of these patients. In an additional 51 patients undergoing thyroidectomy, a thyroid cancer was found that was less than 0.5 cm in diameter and had not been suspected preoperatively. These lesions

DISCUSSION

Our first goal was to test the hypothesis that an association exists between thyroid cancer and clinical markers of autoimmune thyroid disease. The statistical power of finding such a relationship was enhanced by investigating an endocrine referral population with a higher prevalence of autoimmune thyroid disease than that of about 10% observed in unselected populations (4). The thyroid cancer cohort included all patients with thyroid cancer in the nodule under investigation plus all patients

CONCLUSION

In patients with ultrasonography-confirmed thyroid nodules, elevated levels of TgAb were associated with an increased risk of any thyroid cancer as well as clinically significant thyroid cancer. Elevated TPOAb levels were not associated with an increased risk of thyroid cancer. These results are consistent with the hypothesis that thyroid inflammation is tumorigenic, but other interpretations may explain this relationship. If these results can be confirmed in a prospective study of an

DISCLOSURE

The authors have no multiplicity of interest to disclose.

ACKNOWLEDGMENT

For performing the statistical analysis and for expert statistical advice, we acknowledge Maggie N. Kuchibhatla, PhD, Associate Professor of Biostatistics, Duke University Department of Statistics, Durham, North Carolina. For advice about presenting and interpreting our results, we are grateful to Dr. Lewis E. Braverman. We also thank the Wilmington Endocrinology staff, especially Brandy Lundberg, Karly Rivenbark, and Jessica Burcham, for their tireless effort and assistance in helping with

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