Factores pronósticos en el microcarcinoma papilar familiar de tiroidesestudio multicéntrico español

Abstract

The incidence of papillary thyroid carcinoma has risen over the last few decades. Generally it has an excellent prognosis and a less aggressive behaviour than carcinomas of >1 cm, which is why some groups suggest conservative treatment with active surveillance. Familial affection in papillary carcinoma is a recognised condition and generally considered more aggressive and with a worse prognosis. With familial screening it presents more and more often as a microcarcinoma, for which reason the incidence of familial papillary microcarcinoma has also risen. However, while there are many studies that analyse the prognostic factors in sporadic microcarcinoma, there is little information on these factors in the familial form, and although familial microcarcinoma shows a more aggressive behaviour, there are no conclusive data to indicate a more aggressive treatment. The aim of the present study is to analyse the recurrence rate, disease-free interval (DFI) and prognostic factors associated with the recurrence of familial papillary microcarcinoma, as well as the relevance of staging according to the 7th and 8th edition of the AJCC staging system in relation to this prognosis. A multicentre observational study, endorsed by the Spanish Association of Surgeons, was conducted nationwide over a period of 4 years (2015-2018). The study includes 94 patients with a diagnosis of familial papillary microcarcinoma, who belonged to 60 families with familial papillary carcinoma and had at least 2 first-degree relatives diagnosed with FPC. Sociofamilial, clinical, histopathological and prognostic variables were analysed as risk factors for recurrence (TNM according to AJCC 7th and 8th edition and American Thyroid Association risk stratification). The recurrence rate was studied for each variable, a Cox analysis done, and the DFI and overall survival rate studied using the Kaplan-Meier method. After a mean follow-up of 73.32 ± 59.391 months we diagnosed 13 recurrences (13.8%) in the 94 cases of familial papillary thyroid microcarcinoma (FPTMC). The overall DFI was 207.96±11.56 months. The prognostic factors showing significant association with recurrence were tumour size (p=0.029), histological variant of diffuse sclerosis (p=0.040), lymph-node involvement (p=0.010), vascular involvement (p=0.013), extracapsular spread (p<0.001), presence of metastatic adenopathies (p=0.032) and evaluation of the ATA risk of recurrence (p<0.001). In the survival analysis we also found a significant difference in DFI for all these factors. The most relevant factors, obtained from the multivariate analysis, were tumour size (p=0.011), ATA risk of recurrence (p<0.001) and histological variant of diffuse sclerosis (p=0.034). No association was found with age, gender, number of affected family members, thyroid function or clinical features. There was also no association found with bilateralness and multifocality, although there was a high percentage (56.4%) of multifocal lesions. The recurrence rate of familial papillary thyroid microcarcinoma in our Spanish multicentric study is 13.8%. There is a high rate of multifocality: more than 50% of the cases. The most significant prognostic factor for recurrence was tumour size and there was also a considerable predictive value for risk of recurrence according to the American Thyroid Association. The 8th edition of the American Joint Committee on Cancer is not more effective for the prognosis of familial papillary thyroid microcarcinoma. The number of family members with papillary thyroid microcarcinoma was not found to be related to.