Dottorato in TECNOLOGIE AVANZATE IN CHIRURGIA

Titolo della tesi: IL CARCINOMA DELLA PARATIROIDE IN ITALIA: STUDIO MULTICENTRICO NAZIONALE

Introduction Parathyroid cancer (PC) is an uncommon malignancy accounting for 0.5-5% of primary hyperparathyroidism (PHPT) cases, with no gender predominance and peak incidence in the fifth decade of life. PC presents with the clinical manifestations of the PHPT, while those attributable to the tumour burden appear only belatedly, due to an indolent tendency to local invasion Atypical parathyroid tumour (APT) demonstrates atypical cytological and architectural features similar to PC and has uncertain malignant potential. The literature is lacking evidence from large series that examines the incidence of PC and APT as diagnosed after parathyroid surgery and that may help analyse the diagnostic and prognostic features of these diseases, informing timely and adequate surgical treatment. The IPCSG designed a multicenter retrospective study to specify the incidence of PC among parathyroidectomies, to contribute to the existing knowledge of the peculiar clinical, functional, and imaging characteristics of PC, and to better focus on its differences from APT. Materials and Methods Data were obtained through a form sent to the 23 Italian Institutions part of the IPCSG, collecting all relevant information about PC and APT patients treated between January 1, 2009, and December 31, 2021. Minimum follow-up period was of at least 6 months. The study population consisted of 7857 patients who had undergone parathyroidectomy. Perioperative, pathologic and follow-up variables were obtained for PCs and APTs, which constituted the two study groups; statistical comparison of clinico-pathological variables was between the study groups. Results Of 7857 patients who had undergone parathyroidectomy, 336 patients (4.3%; mean age: 59.0±14.6; range: 16-88 years; F= 203, 60.4%), were divided in the APT group (n= 218, 2.8%) and in the PC group (n=118, 1.5%). Significant differences were found between PCs and APTs in terms of clinical features at presentation (male gender, thyroid disorders, bone, abdominal, cardiovascular and neurological symptoms), preoperative laboratory tests (serum albumin-corrected calcium, intact PTH, inorganic phosphorus), imaging (size >3cm, suspect nodal metastasis), operative (concomitant thyroid surgery, central compartment dissection, surrounding structures resection), perioperative complications (transient hypoparathyroidism, unilateral permanent vocal fold palsy). WHO 2022 criteria application to formerly classified PC and APT specimens did not result in a significant change in the relative proportion of cases of PC and APT in the study groups. Conclusion Symptomatic hyperparathyroidism, especially with bone involvement, high values of PTH and albumin-corrected serum calcium, and a US diameter of more than 3 cm, may be considered features of high suspicion of parathyroid carcinoma, differentiating it from the atypical parathyroid tumour. Evidence produced by this study may help raise appropriate suspect of PC preoperatively and guide timely and adequate surgical approach to PC