RESUMEN
BACKGROUND: Familial papillary thyroid microcarcinoma (FPTMC) appears to be more aggressive than sporadic papillary thyroid microcarcinoma (SPTMC). However, there are authors who indicate that unicentric FPTMC has a similar prognosis to SPTMC. The objective is to analyze whether unicentric FPTMC has a better prognosis than multicentric FPTMC. DESIGN AND METHODS: Type of study: National multicenter longitudinal analytical observational study. STUDY POPULATION: Patients with FPTMC. STUDY GROUPS: Two groups were compared: Group A (unicentric FPTMC) vs. Group B (multicentric FPTMC). STUDY VARIABLES: It is analyzed whether between the groups there are: a) differentiating characteristics; and b) prognostic differences. STATISTICAL ANALYSIS: Cox regression analysis and survival analysis. RESULTS: Ninety-four patients were included, 44% (n = 41) with unicentric FPTMC and 56% (n = 53) with multicentric FPTMC. No differences were observed between the groups according to socio-familial, clinical or histological variables. In the group B a more aggressive treatment was performed, with higher frequency of total thyroidectomy (99 vs. 78%; p = 0.003), lymph node dissection (41 vs. 15%; p = 0.005) and therapy with radioactive iodine (96 vs. 73%; p = 0.002). Tumor stage was similar in both groups (p = 0.237), with a higher number of T3 cases in the group B (24 vs. 5%; p = 0.009). After a mean follow-up of 90 ± 68.95 months, the oncological results were similar, with a similar disease persistence rate (9 vs. 5%; p = 0.337), disease recurrence rate (21 vs. 8%; p = 0.159) and disease-free survival (p = 0.075). CONCLUSIONS: Unicentric FPTMC should not be considered as a SPTMC due to its prognosis is similar to multicentric FPTMC.