Thyroid carcinoma associated with other primary neoplasms, a single center study

Thyroid carcinoma is the most frequent endocrine malignancy. It develops following a complex interaction of environmental and genetic factors. Its incidence is on the rise mostly due to the frequent diagnosis of microcarcinomas (tumor <1 cm). In most cases, it has very good prognosis and survival rates. The incidence of a second primary malignancy in thyroid cancer patients is higher than in the general population. In this article, we focus on the role of BRAF V600E mutation in the development of other primary neoplasms associated with thyroid carcinoma.

This study was conducted in the department of Nuclear Medicine and Genetics of the "Prof. Dr. Ion Chiricuță" Institute of Oncology of Cluj-Napoca. We evaluated patients with thyroid carcinoma, who were diagnosed and treated for other malignancies such as breast, colorectal, lung cancer and malignant melanoma. In addition, we tested for the BRAF V600E mutation using paraffin samples of patients.

We identified 17 patients that had thyroid carcinoma associated with other primary malignancies. Two of the patients included in the study had three associated primary cancers. The time interval between the diagnoses of two primary neoplasms in the same patient was 6.15 years, with a standard deviation (SD) of 5.39 years. The most common primary tumor associated with thyroid carcinoma in this study was breast cancer. We applied genetic testing for the BRAF V600E mutation in 12 patients. The BRAF V600E mutation positivity rate was 26.9% and most of the cancer associations were metachronous (occurring at least 6 months after thyroid cancer).

The BRAF V600E mutation is an important prognostic factor in the neoplasms included in this study, but its presence is not a predictive factor for the appearance of a metachronous or synchronous associated primary neoplasm to thyroid cancer.