Association Between Breast and Thyroid Lesions: A Cross-Sectional Study Based on Ultrasonography Screening in China.

Prior research has shown an association between breast and thyroid cancers, although their relationship is unclear. In China, asymptomatic women undergoing regular health checkups usually undergo breast and thyroid ultrasonography screening. The present cross-sectional ultrasound-based study estimated the prevalence of breast masses (BM) and thyroid nodules (TN) and their relationship among a population-based cohort of Chinese women. This study included 34,184 consecutive asymptomatic Chinese women who underwent both breast and thyroid ultrasound evaluation during one health care examination. Detected lesions were assigned into categories of different malignant risks according to the Breast and Thyroid Imaging Reporting and Data System (BI-/TI-RADS). Binomial logistic regression was used to determine the association between occurrence of BM and TN, and multinomial logistic regression was used to analyze the correlation of BM and TN in different BI-/TI-RADS categories. Associations between BM and TN, as well as anthropometric and biochemical markers, were also explored. Of those enrolled, 6371 (18.6%) had BM, 12,153 (35.6%) had TN, and 2279 (6.7%) had both. After adjusting for age, body mass index (BMI), and height, females with TN had a higher risk of BM (odds ratio [OR] = 1.151, 95% confidence interval [CI 1.081-1.225],  < 0.0001) than those with normal thyroids, and females with BM had a higher risk of TN (OR = 1.165 [CI 1.096-1.238],  < 0.0001) than those without BM. Women with a TN >10 mm (OR = 1.249 [CI 1.104-1.413],  = 0.0004) and those with a TN ≤10 mm (OR = 1.134 [CI 1.062-1.211],  = 0.0002) were at higher risk of BM compared with those with normal thyroids. As RADS categories increased, so did the correlation between BM and TN. The increased risk of TN was associated with a higher BMI, height, systolic blood pressure, and a lower plasma albumin level. The increased risk of BM was associated with a lower BMI, plasma albumin levels, and higher height. A high prevalence of BM and TN was detected by ultrasonography screening in this cohort of Chinese women. These lesions occurred frequently and simultaneously, particularly in women with lesions in higher RADS categories.