Increased risk of papillary thyroid cancer in systemic sclerosis associated with autoimmune thyroiditis

Patients with SSc have an increased risk of malignancy compared with the general population. Before now, no study has evaluated the risk of thyroid cancer (TC) in SSc patients. The aim of the study was to evaluate the prevalence of TC in SSc patients.

We studied the prevalence of TC in 327 unselected SSc patients in comparison with two population-based, gender- and age-matched control groups (654 subjects from an iodine-deficient area and 654 subjects from an iodine-sufficient area). Thyroid status was assessed by measurement of circulating thyroid hormones and autoantibodies, thyroid ultrasonography and fine-needle aspiration cytology (when necessary).

Circulating thyroid-stimulating hormone, anti-thyroglobulin and anti-thyroperoxidase antibody levels, and the prevalence of hypothyroidism were significantly higher in SSc patients (P < 0.01, for all). Six patients with papillary TC (PTC) were detected among SSc patients, whereas only one case was observed in each of controls 1 and 2 (P = 0.007, for both). In SSc all patients with TC had evidence of thyroid autoimmunity vs 40% of the other SSc patients (P = 0.001).

These data suggest a high prevalence of papillary TC in SSc patients, in particular in the presence of thyroid autoimmunity; careful thyroid monitoring would be opportune during the follow-up of these patients.