ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2017) 49 EP1407 | DOI: 10.1530/endoabs.49.EP1407

Histologically-proven Hashimoto's thyroiditis significantly decreases the risk of structural recurrence in patients with low risk intra-thyroidal papillary thyroid cancer

Vincenzo Marotta1,2, Concetta Sciammarella2, Maria Grazia Chiofalo3, Claudio Gambardella4, Claudio Bellevicine5, Marica Grasso6, Giovanni Conzo4, Gerardo Botti6, Simona Losito6,7, Giancarlo Troncone5, Luciano Pezzullo3, Annamaria Colao1 & Antongiulio Faggiano3

1Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy; 2IOS & COLEMAN s.r.l., Naples, Italy; 3Thyroid and Parathyroid Surgery Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori-IRCCS ‘Fondazione G. Pascale’, Naples, Italy; 4Department of Anesthesiologic, Surgical and Emergency Sciences, Division of General and Oncologic Surgery, University of Campania Luigi Vanvitelli, Naples, Italy; 5Department of Public Health, University of Naples ‘Federico II’, Naples, Italy; 6San Giovanni di Dio e Ruggi D’Aragona, Universitary Hospital, Division of General Surgery, University of Salerno, Salerno, Italy; 7Department of Pathology, Istituto Nazionale per lo Studio e la Cura dei Tumori-IRCCS ‘Fondazione G. Pascale’, Naples, Italy.

Introduction: Due to the absence of randomized controlled trials, management of low risk papillary thyroid cancer (PTC), which represents the most commonly diagnosed form of thyroid malignancy, remains controversial. Hashimoto’s thyroiditis (HT) is significantly more frequent in patients with PTC, as compared with subjects carrying benign lesions as well as different tumour histotypes. Despite still controversial, HT is considered a protective factor in PTC being associated with favourable tumour features and better outcome. Nevertheless, all studies dealing with this issue included all PTC stages. We aimed to assess prognostic value of histologically-proven HT in a large cohort of consecutive low-risk intra-thyroidal PTC.

Patients and methods: Multicenter retrospective study including pT1/2 PTC without any evidence of extra-thyroidal disease, who were subjected to surgery and follow-up within the involved centers. Pathological review of all specimens was performed. Co-existing HT was defined by the presence of diffuse/focal lymphoplasmacytic infiltrate, oxyphilic cells, lymphoid follicles with germinal centers, and atrophic changes involving normal thyroid tissue, whereas isolated peri- and intra-tumoral lymphocytic infiltration was not considered as HT. Study endpoint was recurrent structural disease.

Results: Two-hundred eighty-four patients (156 without and 128 without HT) were included. Mean follow-up was 75±61 months (6.3 years). Concomitant HT was related to significantly lower rate of recurrent structural disease (P=0.018, OR 0.33 95% CI 0.13–0.86). This finding was confirmed by survival analysis, where PTC with HT showed significantly higher recurrence-free time. After adjustment for other variables affecting prognosis at univariate analysis (age at diagnosis, tumour size, multifocality, and post-surgery radiometabolic treatment), concomitant HT retained its protective effect (P=0.036, OR 0.34 95% CI 0.12–0.93).

Conclusions: In our series of low risk intra-thyroidal PTC, concomitant HT independently predicted recurrent structural disease and may therefore represent a useful tool for the decision-making process of these patients.