Risk factors for malignancy in multinodular goitres.

Background: Multinodular goitre (MNG) is quite often associated with thyroid carcinoma, but the risk factors for malignancy are not well known. The aim is to analyse patients with thyroid carcinoma associated with MNG to determine the clinical risk factors for malignancy.

Method: From a series of 672 MNGs we analysed a subgroup of 59 patients presenting with an associated thyroid carcinoma. The variables analysed were age, sex, family history, cervical radiation therapy, residence in areas of endemic goitre, prior thyroid surgery, time of evolution, asymptomatic status, hyperthyroidism, compressive syndromes, intrathoracic prolongation, goitre consistency and cervical adenopathies. These were compared to MNGs not developing malignancy using the Chi-squared test, Student's t test and a logistic regression test.

Results: Of the 59 cases, 37 corresponded to a microcarcinoma (< or =1 cm). The most common histological type was papillary (n=48), followed by follicular (n=6). In 20 cases the carcinoma was multifocal, and capsular involvement was noted in 16 patients, lymph node involvement in five and vascular involvement in another five. The multivariate analysis confirmed the following as independent variables associated with the presence of carcinoma: family history of thyroid pathology (RR=1.6), history of cervical radiation therapy (RR=1.8), recurrent goitre (RR=2.1) and presence of adenopathies on physical exploration (RR=1.6).

Conclusion: The risk factors for carcinoma associated with MNG are family history of thyroid pathology, personal history of cervical radiation therapy, prior surgery and presence of cervical adenopathies.