Correlation between urinary iodine and clinical characteristics in breast cancer

Objective To explore the relationship between urinary iodine level and breast cancer, we compare urinary iodine excretion levels in patients with breast cancer, benign breast disease, other female malignant tumors and control subjects in Xiangya Hospital of Central South University. Methods From December 2018 to January 2019, 64 patients with newly diagnosed breast cancer in Xiangya Hospital of Central South University were selected as case group, benign breast disease group (n=49), other female malignant tumor group (n=39) and health examination group (n=50) as control group. Urinary iodine was determined by colorimetry. According to the urinary iodine level the patients divided into three groups: iodine excess (>300 μg/L), medium iodine (100-300 μg/L) and iodine deficiency (<100 μg/L). The relationship between urinary iodine and clinicopathology of breast cancer was analyzed. Results The level of urinary iodine in benign breast nodule group 319.13(163.98)μg/L > breast cancer group 273.96(151.30)μg/L > female other malignant tumor group 212.95(161.71)μg/L > normal control group 199.15(194.45)μg/L, with significantly differance (H=9.936, P=0.019). Urinary iodine level in the normal control group was significantly lower than that in the benign breast disease group (P=0.013). The patients were further divided into three groups according to the urinary iodine level: iodine excess, iodine medium and iodine deficiency, the number of urine iodine <100 μg/L in the normal control group was significantly higher than that in the breast cancer group (P=0.021). The level of urinary iodine was negatively correlated with the size of the primary focus of breast cancer (Z=-2.307, P=0.021). The effect of urinary iodine was analyzed by multiple linear regression method. The size of primary focus was included in the regression equation (R2=0.136 , P=0.007), but had nothing to do with lymph node metastasis and the expression status of estrogen receptor (ER), androgen receptor (AR), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER-2). Conclusions There is a negative linear correlation between urinary iodine level and the size of primary focus of breast cancer, but it has nothing to do with lymph node metastasis and the expression of ER, AR, PR and HER-2. Key words: Breast neoplasms; Urinary iodine; Sodium iodine symporters