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Medicine

Precision in double

Combined exams perfect the diagnosis of cancer of the thyroid

Months ago, with two thyroid nodules, Neide G.W., 60 years of age, found herself on the edge of being submitted to an unnecessary surgery. The biopsy of the larger nodule, done from a sample of the tissue extracted with a fine needle, was not conclusive about the possibility of being a cancer. The most common procedure in this type of case, given the size of the nodule of two centimeters in diameter, is the partial or total removal of the thyroid gland, an option that implies risks through the location of this gland, the neck, intensely irrigated and rich in nerve endings. Neide escaped from the scalpel thanks to a new method of diagnosis of thyroid cancer developed by the specialist in ultra-sound Eduardo Kiyoshi Tomimori and the endocrinologist Rosalinda Camargo, doctors at the Hospital das Clínicas of the Medical School of the University of São Paulo (USP).

Instead of using only one parameter to decide on surgery, the researchers formulated a method which takes into consideration two indicators. Firstly, they take an ultra-sound, a low cost exam, capable of providing information about the volume, solid or liquid content, contours and presence of not of calcification in the nodules. If the images indicate something abnormal, they make a punch and carry out a biopsy only in the suspected formations, in order to have a microscopic evaluation of the cells of the lumps. Combining the results of the ultra-sound and the biopsy, they manage an index of correctness of 76% in the detection of thyroid cancer.

Through this approach, three of every four people who are sent to the operating table have malignant tumors. According to Rosalinda, the doubtful cases will not be neglected. “It is highly improbable that a patient would pass through the double evaluation with a false negative diagnosis.” In the surgeries recommended through the traditional method of diagnosis (palpation and punch biopsy of the largest nodule only), the suspicion of cancer is confirmed in, at the maximum, 20% of the cases operated.

Japanese inspiration
The idea for the method began to gain ground in 1996, with their visit to a center specialized in thyroid illnesses in Kobe, Japan. There, all the biopsy punches were guided by the results of the ultra-sound test, and the nodules classified, in accordance with the images, in degrees that indicate the chances of them being malignant. Back to São Paulo, Rosalinda and Tomimori prepared a specific classification for Brazilian reality, different from the Japanese. In that country, thyroid cancer is much more frequent than here, where 2% of the population show this type of tumor.

For the next step, they carried out a study relating the ultra-sound images and cytological findings on 2,025 patients with thyroid nodules. This was when they arrived at a system of number arbitration for the tumors, based on the potential of a malignant formation. Each nodule receives two scores, one provided by the biopsy (1, 2, 3 or 6) and the other by the ultra-sound (1, 2, 3 or 4). When the sum of the scores is equal to or higher than 6, the patient goes forward for surgery. The nodules whose final score lies between 2 and 4 are considered to be benign, and those with 5 points are doubtful, but probably benign. Tumors with 6 points are suspect cases and between 7 and 10 points are probably malignant.

This result came from the comparison of the diagnostics provided by the new method with the analyses of the nodules extracted from 224 patients operated on at the Hospital das Clínicas of USP. Of the 52 patients of nodules seen as benign, only two (3.8%) showed papilliferous carcinoma, the less aggressive thyroid tumor. Among the 35 with lumps on the neck classified as doubtful, four (11.4%) had cancer. The percentage of malignancy jumped to 44.6% among the 56 people with suspect nodules. Almost 99% of the 81 patients with an index higher or equal to 7, clearly malignant, had cancer.

Conclusion: If only those who had a final score equal to or greater than 6 had been sent to the operating theater, they would arrive at an elevated index of correctness in the diagnosis of the disease, 76.9% of the cases. From that point onwards the score of six became the watershed. As a general norm for the procedure, the doctors of the HC recommend that all the biopsy punches, whenever possible, should be guided by the ultra-sound.

With the help of this exam, the punch of small nodules, not palpable but of a suspect aspect, becomes more productive. The ultra-sound permits the choice of the region of the nodule with a greater chance of containing malignant cells, reducing the percentage of suctions that need to be repeated due to insufficient or inadequate collection of material.

“What we will spend more on ultra-sound is a lot less than what we will save with expenses and the suffering involved in unnecessary punches and surgeries”, says Tomimori. According to him, the extraction of the thyroid can cost as much as R$ 5,000.00 when it is not covered by a health plan. Besides the HC in São Paulo, the Socor Hospital of Belo Horizonte, is already using the method created at USP.

The Project
New Methodology for the Precocious Diagnosis of Distinct Thyroid Cancer based on the Results of Ultra-sound and Cytological Evaluation (nº 97/07713-8); Modality Regular line of research assistance; Coordinator Dr. Rosalinda Yossie Asato de Camargo – Medical Faculty/USP; Investment R$ 60,367.30 and US$ 18,343.95

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