Article reviews rare cardiac metastases of thyroid cancer

Even among the most virulent types of metastatic thyroid cancer, the carcinoma is very unlikely to migrate to the heart, which is why a team of Australian researchers recently compiled a list of all cardiac metastases of thyroid tumors (CMTTs) recorded in the last 130 years.

Creating the list involved a far-reaching search of more than a century of medical literature, which contains very few instances of CMTTs. The group, which is based in Melbourne's Alfred Health Hospital and Monash University, counted just 54 cases since 1881.

Their full meta-study, including pathological and clinical summaries of all 54 instances of CMTT, appeared in the journal Thyroid.

While primary malignant cancers of the cardiac muscle are quite rare - hence the exotic sound of the phrase "heart cancer" - they are not unheard of, according to a report in the journal Cancer. CMTTs are slightly more common, but they still entail a very poor prognosis, based on the new study.

The team found that the form of thyroid cancer most likely to result in a CMTT is anaplastic thyroid cancer (ATC), the gravest of all carcinomas associated with the gland.

ATC accounts for just 1 percent of all thyroid cancers, but it nearly always results in death, typically within six months of the initial diagnosis, the National Institutes of Health states.

The next most common primary thyroid tumors associated with CMTTs were follicular thyroid carcinomas, followed by papillary thyroid cancer.

How long do patients with a CMTT typically survive beyond their diagnosis? It is difficult to say, not least because prior to the 1980s, doctors almost unilaterally discovered these cardiac masses during patients' autopsies.

Also, many of the surveyed reports did not list the circumstances of diagnosis. Nevertheless, the authors noted that the most common survival time for living patients diagnosed with a CMTT was three months.

Despite the rarity of the condition, researchers concluded that doctors should screen for CMTTs in thyroid cancer patients with unusual cardiac symptoms.

"In patients with established thyroid malignancy, particularly FTC, who develop cardiac arrhythmias, new murmurs or signs of cardiac decompensation, it is essential that cardiac metastases be considered," the authors concluded.