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Novel Blood Test Enhances Current Method of Detecting Thyroid Cancer,
Potentially Reducing Unnecessary Surgery

(PALM BEACH, FLA., Sept. 19, 2003) - For the first time, a blood test has been shown to distinguish between thyroid cancer and non-cancerous thyroid nodules, potentially reducing some unnecessary surgeries, according to the results of a new study being presented today at the 75th Annual Meeting of the American Thyroid Association.

Currently, the distinction between thyroid cancer and benign nodules can only be made by fine needle aspiration (FNA) biopsy, which involves removing cells from the body and identifying cancer cells under the microscope. The limitation of FNA is that a significant number of these biopsies lack adequate cellular material to make or rule out conclusively the diagnosis of cancer, which can lead to unnecessary surgeries to remove harmless nodules.

"This blood test can complement fine needle aspiration biopsy and can actually reduce the necessity for some thyroid surgeries," said Manjula Gupta, PhD, senior author of the study and medical director of the Endocrinology and Cancer Marker Laboratory at The Cleveland Clinic Foundation.

Thyroid stimulating hormone (TSH) receptors are cell-surface proteins specific to normal or cancerous thyroid cells. Presence of this protein is necessary for thyroid cells to respond to TSH signals to make thyroid hormones as well as to maintain their growth. Although both normal and thyroid cancer cells express TSH receptors, only cancer cells attempt to make their way into the bloodstream. Armed with this knowledge, researchers at The Cleveland Clinic previously found that when the TSH receptor message ribonucleic acid (TSHR mRNA) is detected in blood, cancer cells are present.

For these reasons, the researchers wanted to assess the use of the blood test for TSHR mRNA to find out if the test could accurately distinguish between benign and malignant cells before operating to remove a nodule. Pre-operatively, they tested 38 patients, 16 with benign disease and 22 with thyroid cancer, and compared the results with the FNA results. Post-operatively, they also tested 28 of the original group. In this study, 39% of the FNA samples were considered inadequate to test accurately for cancer. However, TSHR mRNA correctly classified 10 of 13, or 77 percent, of inadequate FNA samples, enhancing the accuracy of FNA from 61 percent to 91percent. The diagnostic sensitivity -percentage of cancer cases detected by the blood test- was 73 percent, and the specificity -percentage of benign cases not detected by the test -was 81 percent.

Sensitivity and specificity are both important to correctly classify disease state. "High sensitivity is desirable for the screening test even if the test shows relatively low specificity," explained Dr Gupta. "Such a test must then be confirmed by another more specific test. In our case, the two tests complimented each other to enhance both sensitivity and specificity and must be performed simultaneously to obtain the best disease differential."

All patients with positive results preoperatively were negative the day following surgery, except one with pulmonary metastases. "This is a small study, and the findings are preliminary," added Dr. Gupta. "We intend to follow this study with a larger one to confirm these findings."

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