Hashimoto’s thyroiditis predicts outcome in intrathyroidal papillary thyroid cancer.
Ultrasound of a patient with Hashimoto’s thyroiditis with a coexistent papillary thyroid cancer
Hashimoto’s thyroiditis (HT) seems to have favourable prognostic impact on papillary thyroid cancer (PTC), but data were obtained analyzing all disease stages. Given that HT-related microenvironment involves solely the thyroid, we aimed to assess relationship between HT, as detected through pathological assessment, and outcome in intrathyroidal PTC. This was a multicenter, retrospective, observational study including 301 PTC with no evidence of extrathyroidal disease. Primary study endpoint was the rate of clinical remission. Auxiliary endpoint was recurrence-free survival (RFS). HT was detected in 42.5% of the cohort and was associated to female gender, smaller tumour size, lower rate of aggressive PTC variants, and less frequent post-surgery radio-iodine administration. HT showed relationship with significantly higher rate of clinical remission (p<0.001, OR 4, 95% CI 1.78-8.94). PTCs with concomitant HT had significantly longer RFS, as compared with non-HT tumours (p=0.004). After adjustment for other parameters affecting disease outcome at univariate analysis (age at diagnosis, histology, tumour size, and multifocality), prognostic effect of HT remained significant (p=0.006, OR 3.28, 95% CI 1.39-7.72). Nevertheless, assessment of HT accuracy as prognostic marker showed poor capability of identifying patients with unfavourable outcome (negative predictive value of clinical remission was 21.05, 95% CI 18.2-24.22). Our data show that HT represents an independent prognostic parameter in intrathyroidal PTC, but cannot improve prognostic specificity.
Comment: While HT is a good marker for favorable outcomes in papillary cancer it was not able to determine which HT/PTC cases had unfavorable outcomes.