Metastasis of breast cancer to the thyroid gland a case report and review of literature

Metastasis to the thyroid is not as rare as previously was believed. Its incidence has been shown in autopsy series, to be more than the incidence of primary thyroid malignancy. Breast cancer is the most common cancer in women and one of the cancers that metastasize to the thyroid gland.We had a young patient with breast cancer who presented with thyroid mass confirmed to be a metastasis from breast cancer so we reviewed the literature. We reviewed all available papers about secondary thyroid malignancies from 1960 to 2007.Total of 41 papers were found that most of them had discussions about breast cancer metastasis to the thyroid gland. We extracted the incidence, time between diagnosis of breast cancer and thyroid involvement, common signs and diagnosis and treatments that were recommended. The overall incidence of metastasis in the thyroid gland varies from 1.25% in unselected autopsy series to 25% in autopsy of patients with widespread malignancies. The most frequent metastasis to thyroid is from renal cancer, lung cancer and breast cancer. The time between breast cancer diagnosis and metastasis to the thyroid has been reported 2 to 180 months. Almost inarticles breast cancer was one of three most common cancers with tendency for metastasis to the thyroid. The presenting symptom was thyroid solitary or multiple nodule, the diagnosis was made by FNA in most cases but core or open biopsy was necessary in few patients for diagnosis. Treatment was thyroidectomy or lobectomy in most patients except for patients with widespread metastasis to other organs that were treated with chemotherapy alone. Breast cancer is one of most common cancers that metastasize to thyroid gland. It its recommended in any patient with a known history of previous carcinoma, the appearance of a new thyroid mass should be regarded as potentially metastasis. If we consider high incidence of breast cancer among women and also high incidence of thyroid masses in Iranian women, we find it is not a rare condition if we meet a breast cancer survivor who has thyroid mass too. So it is important for a clinician to have enough information about thyroid metastatic cancers.