Thyroid Research Thyroid Research Archive Thyroid Cancer

Small papillary thyroid carcinomas grow very slowly

(July 2003)

The background of the study. Papillary thyroid carcinomas that are ≤1 cm (0.4 in.) in diameter are called microcarcinomas. They are usually detected by chance, and the diagnosis is confirmed by fine-needle aspiration biopsy. In this study, the growth rate of microcarcinomas was studied in patients who declined surgery at the time of initial diagnosis.

How the study was done. The study subjects were 732 patients with thyroid nodules ≤1 cm in diameter detected by ultrasonography and found on fine-needle aspiration biopsy to have the cytologic changes of papillary carcinoma. The patients were offered two options—immediate surgery, or observation with periodic ultrasonography and repeat biopsy.

The results of the study. Among the 732 patients, 570 chose immediate surgery and 162 chose to be followed. The mean tumor diameter was 7 mm. During an average follow-up period of 46 months (range, 18 to 113), the microcarcinoma did not change (as defined by an increase or decrease of <2 mm in maximal diameter) in approximately 65 percent of the patients, it increased by ≥2 cm in 25 percent, and it decreased by ≥2 cm in 10 percent.

Among the 162 patients not operated on initially, 56 had surgery 19 to 56 months later. The tumor had increased in size in 23 percent, had decreased in 13 percent, and had not changed in 64 percent. On histologic study, all the tumors proved to be papillary carcinomas.

During an average postoperative follow-up period of 49 months, 16 of the 626 patients (3 percent) who were operated on had a recurrence. No patient died from papillary carcinoma.

The conclusions of the study. Most papillary thyroid microcarcinomas do not enlarge during the first five years after diagnosis.

The original article. Ito Y, Uruno T, Nakano K, Takamura Y, Miya A, Kobayashi K, Yokozawa T, Matsuzuka F, Kuma S, Kuma K, Miyauchi A. An observation trial without surgical treatment in patients with papillary microcarcinoma of the thyroid. Thyroid 2003;13:381-7.