New research has found that measuring sections of genetic material within papillary thyroid cancer tumors could predict the chance of recurrence following surgery. This is according to a study published in the journal Cancer.

Researchers from Australia say they also discovered that elevated blood levels of this genetic material, known as microRNAs, could also indicate an increased chance of recurrence after thyroidectomy – the surgical removal of all or part of the thyroid gland.

Previous research has shown that abnormalities in microRNAs – short segments of genetic material that regulate gene expression – may play a part in the development of cancer. The researchers say that microRNA “signatures” can be used to determine different types of thyroid tumors.

For their study, the researchers analyzed tumor tissue from patients with papillary thyroid cancer and multinodular goiter – lumps on the thyroid glands.

Their findings showed that high levels of two microRNAs found in tumor tissue – microRNA-222 and -146b – suggested that the cancer was more likely to recur in patients after their tumors had been surgically removed.

When testing the blood of thyroid cancer patients, the researchers found that high levels of the same two microRNAs were present. However, the levels of these two microRNAs reduced to normal levels following thyroidectomy.

Explaining their findings, the researchers say:

In this study, we identified tumor miR-222 and miR-146b as strong predictors of PTC (papillary thyroid cancer) recurrence, and they may be useful in guiding adjuvant therapy and surveillance intensity.

Circulating levels of the same miRNAs also were correlated with the presence of PTC and MNG (mutinodular goitre). Therefore, these are potential, noninvasive markers of PTC recurrence to be used in the context of thyroid cancer surveillance.”

Dr. James Lee of the Kolling Institute of Medical Research and the University of Sydney explains that results may help doctors select which patients with thyroid cancer may benefit from more aggressive additional treatment or closer monitoring following surgery.

“As most patients with papillary type thyroid cancer do very well with standard treatment,” he adds, “we are always working on ways to help us select the small group that do not fair so well so we can use our medical resources more efficiently and minimize interruptions to patients’ lives.”

Furthermore, Dr. Lee says that the elevated levels of the two microRNAs found in the blood of thyroid cancer patients suggests that doctors could test for the presence of thyroid cancer using a microRNA blood test.

Although there is already a blood test available that can detect thyroid cancer, Dr. Lee says that the results are inaccurate in up to 25% of patients as a result of interference from the patients’ antibodies, among other factors.

“Therefore, an alternative blood test measuring microRNA levels would be a great complement to what is already available,” he adds.

The researchers say that further studies are needed to find out whether blood levels of microRNA-222 and -146b increase when cancer recurs. They add that they also need to improve the accuracy of both tests before they go to clinical trials.