Prognostic Value of Histological and Immunohistochemical Characteristics for Predicting the Recurrence of Medullary Thyroid Carcinoma

Introduction: In medullary thyroid carcinoma, there is currently no consensus about the prognostic value of histological and immunohistochemical parameters. This study was designed to analyze the value of various histological and immunohistochemical characteristics for predicting the recurrence of medullary carcinoma.

Methods: A total of 55 cases of medullary thyroid carcinoma have been reviewed. These were operated on consecutively between 1971 and 2004 after histological confirmation. The data referring to clinical characteristics and evolution were taken from the patient's clinical history. The macroscopic, microscopic, and immunohistochemical characteristics of the tumors were taken from the pathological anatomy report.

Results: In 14 (27%) cases, there was recurrence of the disease. The disease-free interval at 1 year was 88 +/- 5%; at 5 years 73 +/- 7%; at 10 years 73 +/- 7%; at 15 years 61 +/- 10%; and at 20 years or more 61 +/- 10%. Of the histological parameters, only vascular invasion (0.0098) was related to a higher relapse rate. No epidemiological variable or immunohistochemical marker was associated with relapse. However, it was found that staging (P = 0.0102), as well as tumor size (P = 0.0211) and lymph node affectation (P = 0.0012), are factors significantly related to relapse of the disease. According to Cox's regression model, the only variable with a statistically significant effect was vascular invasion (P = 0.0056; odds ratio = 5.2308).

Conclusions: The overall recurrence rate was 27%, and the main independent prognostic factor of recurrence was tumoral vascular invasion at diagnosis. Staging, tumor size, and lymph node metastasis are prognostic factors of recurrence, although they are not significant in the multivariate analysis.