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Metastatic disease of the parathyroid gland often overlooked
Parathyroid gland metastases are frequently overlooked and generally indicate a poor prognosis, according to recent findings.
In the literature review, researchers searched the PubMed database up until May 2014 using keywords pertaining to parathyroid cancer, parathyroid metastasis, tumor-to-tumor metastasis and parathyroid carcinoma. The researchers also included data from their own institutional experience of 392 consecutive parathyroidectomies between January 2008 and October 2014.
The researchers analyzed the available evidence on primary and secondary thyroid malignancies, which were place into one of the following three categories: primary parathyroid carcinoma, spread of carcinoma into the parathyroid gland via adjoining extension from the thyroid gland or other head/neck cancer and distant metastases to the parathyroid gland.
After reviewing the studies on tumor-to-tumor metastases, the researchers identified a tendency for endocrine tumors (such as adrenal cortical, thyroid and parathyroid) to be the recipient tumors. This may be due to the abundant blood supply in endocrine tumors, which may promote metastatic disease. The data reported on tumor-to-tumor parathyroid metastases originating from breast cancer, renal cell carcinoma, hepatocellular carcinoma and melanoma.
Of the 392 parathyroidectomies performed by the researchers in their institutional experience, two (0.5%) had cancer, one of which metastasized from a thymic neuroendocrine tumor and another which was primary parathyroid carcinoma.
According to the researchers, parathyroid metastases may be overlooked due to a wish to retain parathyroid function.
“Metastatic disease from other cancers to a benign parathyroid gland or to a parathyroid adenoma probably indicates a grave prognosis for the patient since it likely indicates widespread metastatic disease,” the researchers wrote. “A few case reports, however, indicate that isolated metastases to the parathyroid may occur.”
Disclosure: The researchers report no relevant financial disclosures.