PHOENIX — Younger age and male sex were significantly associated with an increased risk of malignancy in thyroid nodules, according to the results of a study of 371 thyroid cancer patients.
Few risk factors—aside from childhood radiation exposure—have been shown to predict whether a patient's thyroid nodule is malignant, wrote Dr. Leila Yassa of Harvard University and her colleagues in a poster presented at the annual meeting of the American Thyroid Association.
To assess the impact of age and sex on the risk of malignancy, the researchers reviewed data from 2,601 consecutive patients (ages 18–94) with thyroid nodules who had ultrasound-guided fine-needle aspiration of nodules at least 1 cm in size. The patients' mean age was 49 years, and 88% were women. Overall, thyroid cancer (a malignancy at least 1 cm in size) was identified in 297 of 2,280 women (13%) and 74 of 321 men (23%).
Both the presence of multiple nodules and the risk that a nodule was cancerous decreased significantly among women as they aged. Neither of these factors was associated with age in men. In men and women, the highest incidence of cancer occurred among 18- to 30-year-olds: 53 of 235 (23%) women and 9 of 27 (33%) men. But male sex was associated with a 63% increased risk of thyroid cancer independent of age.
An additional 39 patients were diagnosed with a papillary carcinoma less than 1 cm in size in the aspirated nodule, and another 38 patients had an incidental papillary carcinoma less than 1 cm in size in an otherwise benign tissue sample that was not the aspirated nodule. Based on these findings, age and gender can be used to stratify cancer risk in patients with thyroid nodules at least 1 cm in size and to guide counseling efforts and prioritize further evaluation, the researchers said.