Breast cancer is the most prevalent malignancy in the world. Endocrine therapy reduces the level of estrogen in vivo, thus affecting the blood lipid level, which reduces the quality of life and the treatment compliance of patients.

To analyze the clinical characteristics and traditional Chinese medicine (TCM) prescription of hyperlipidemia in estrogen receptor (ER) positive breast cancer patients during endocrine therapy in real world.

Based on method of retrospective study, a total of 238 patients with ER positive breast cancer who received endocrine therapy in Affiliated Hospital of Shandong University of Traditional Chinese Medicine from January 2012 to March 2022 were selected as the study subjects. The data including age, triglyceride, total cholesterol, low density lipoprotein, endocrine therapy drugs, TCM prescriptions of the patients were exported through the search platform of scientific research big data to establish a clinical data table of the patients. ER positive breast cancer patients with normal baseline blood lipid levels were divided into the normal group and dyslipidemia group according to the blood lipid levels during endocrine therapy, and hyperlipidemia was classified into hypercholesterolemia, hypertriglyceridemia and mixed hyperlipidemia. The exported prescriptions were analyzed for frequency, four properties, five flavors, channel tropism and medication regularity by using the "prescription analysis", an auxiliary platform for TCM inheritance, to obtain new prescriptions.

Among 238 ER positive breast cancer patients, 97 patients (40.8%) had normal baseline blood lipid levels, of whom 42 patients (205 person-time return visit) developed dyslipidemia during standardized endocrine therapy. Among the patients with dyslipidemia, 37.6% (77/205) occurred in the age group of 51 to 60 years as the highest number; 86 person-time with dyslipidemia received exemestane treatment, accounting for the highest proportion of 42.0%. Among the 42 patients with dyslipidemia (205 person-time return visit) , hyperlipidemia occurred in 99 person-time, and hypercholesterolemia occurred in 49.5% (49/99) . There was no statistically significance difference in the age of patients with three types of hyperlipidemia (P>0.05) . There were statistically significance differences in the proportion of endocrine therapy types among patients with three types of hyperlipidemia (P<0.05) . There were 189 kinds of TCM prescriptions for hyperlipidemia in ER positive breast cancer patients during endocrine treatment, licorice was the most frequently used medicine (408 times) , the highest frequency of use was tonifying qi drug (22.6%) . The channels of TCM collected by the big data platform were mainly distributed in the spleen, lung and liver channels. The properties of TCM were mainly cold, flat and warm, and the flavors were mainly sweet, bitter and pungent. The combination of "Astragalus and Licorice" had the highest frequency. Six core drug combinations and three new prescriptions were obtained through complex system entropy clustering analysis.

The highest incidence of hyperlipidemia in ER positive breast cancer patients during endocrine therapy is 51-60 years old, and hypercholesterolemia is the most common. The position of hyperlipidemia in ER positive breast cancer patients during endocrine therapy is in the spleen. The medication are maily used for invigorating spleen to remove dampness, tonifying qi and regulating stomach.