The incidence of breast cancer in Chinese women has increased year by year, and luminal A breast cancer commonly occurs in early-stage and postmenopausal women. This type of breast cancer is not sensitive to chemotherapy, although it has a low mortality rate and distant metastasis rate. Studies have shown that luminal A breast cancer is sensitive to endocrine therapy. Patients with breast cancer who undergo excision should be followed up and their prognosis should be monitored regularly. At present, imaging detection is mainly used in the conventional follow-up of breast cancer, but the cost of many imaging examinations is high, so a cost-effective examination is urgently needed.

Recent studies have found that circulating tumor cells can be used as a new type of tumor molecular marker, which can be used to diagnose tumors, judge the prognosis and monitor the efficacy by detecting the number and characteristic protein expression of circulating tumor cells. Because circulating tumor cells may develop abnormalities 4-6 months earlier than conventional imaging examination, as long as circulating tumor cells of patients are abnormal, timely PET-CT examination will neither miss diagnosis nor delay the condition. Simultaneously, the cost of hospitalization can be obviously reduced.

This non-inferiority randomized controlled clinical trial is designed to compare the differences in postoperative conditions between circulating tumor cell detection and conventional imaging examination in patients with luminal A breast cancer without lymph node metastasis.

Breast cancer ranks first in the incidence of female malignant tumors and second in mortality. It is mainly classified into luminal A, luminal B, human epidermal growth factor receptor 2 positive, basal-like and other special types of breast cancer. Epidemiological studies have shown that the incidence of luminal A breast cancer is 44.5-69.0%, mostly in early-stage patients and postmenopausal women, with a low mortality rate and distant metastasis rate. Luminal A breast cancer is usually invasive. Although it is not sensitive to chemotherapy, luminal A breast cancer is sensitive to endocrine therapy. Therefore, the treatment of luminal A breast cancer is a combination of surgery, chemotherapy, radiotherapy and endocrine therapy.

After surgical removal of breast cancer, follow-up should be conducted according to the National Comprehensive Cancer Network guidelines to monitor the prognosis at any time. Conventional follow-up is mainly based on imaging examination, but the cost of many imaging examinations is high, so a cost-effective examination is urgently needed.

Circulating tumor cells are tumor cells that fall off from solid tumors (primary and metastatic foci) and enter the peripheral blood. In recent 30 years, circulating tumor cells have become one of the new tumor molecular markers. Detection of the number and protein expression of circulating tumor cells can diagnose the disease, judge the prognosis and monitor the therapeutic effect. Epithelial-mesenchymal transition and overexpression of epithelial cell adhesion molecule in circulating tumor cells suggest that the prognosis of cancer patients is not good. By comparing the number of circulating tumor cells in blood before and after surgery or radiotherapy and chemotherapy,whether the treatment is effective or not can be judged, which has important clinical research and application value. Currently, many clinical trials have used circulating tumor cells to monitor the prognosis in breast cancer. Circulating tumor cells may develop abnormalities 4-6 months earlier than conventional imaging examination, and PET-CT can only find subclinical lesions 4-6 weeks in advance. Thus, as long as circulating tumor cells of patients are abnormal, timely PET-CT examination will neither miss diagnosis nor delay the condition. Simultaneously, the cost of hospitalization can be obviously reduced.

This non-inferiority randomized controlled clinical trial is designed to compare the differences in postoperative conditions between circulating tumor cell detection and conventional imaging examination in patients with luminal A breast cancer without lymph node metastasis.

Inclusion Criteria:

• estrogen receptor (≥ 10%), progesterone receptor (≥ 10%) and epidermal growth factor receptor 2 negative;
• proliferation index Ki-67 < 20%;
• no lymph node metastasis;
• systemic therapy (chemotherapy, radiotherapy and endocrine therapy) in accordance with the National Comprehensive Cancer Network guidelines;
• provision of informed consent of patients and their families.

Exclusion Criteria:

• Bilateral breast cancer;
• inflammatory breast cancer;
• pregnancy or lactation;
• history of other cancers or chest radiotherapy.

500 patients will be recruited from outpatients and admission office of Shengjing Hospital of China Medical University by posting recruitment notice listing the study details on the bulletin board. The patients will be randomly divided into trial group and control group, with 250 patients per group.