I. Clinical manifestations and diagnosis of male breast cancer 75%～95% male breast cancer patients’ first symptom is painless lump under areola or breast area, the average lump is 3.0～3.5cm, easy to invade the skin and nipple, and there may be skin oedema, ulceration, nipple overflow, blood overflow, nipple inversion and other symptoms. It is usually unilateral, and bilateral is rare. It is often accompanied by axillary lymph node enlargement. Most patients are seen late. When there are multiple risk factors combined, it is more important to pay high attention to timely consultation. Clinical auxiliary diagnosis of male breast cancer in foreign countries is generally preferred to molybdenum target, supplemented by ultrasonography. However, it is difficult to perform mammography for male breast cancer patients in China due to small breast size. In our hospital, only 2 cases of male breast cancer patients have undergone mammogram examination. Ultrasound has higher diagnostic sensitivity and specificity for male breast cancer patients in China, and helps in differential diagnosis. For those who are highly suspected of malignancy by auxiliary examination, it is necessary to perform coarse needle aspiration biopsy on the lump to clarify the pathologic diagnosis. Treatment of male breast cancer Most of the clinical information about male breast cancer comes from the retrospective analysis of the case reports in the past decades, and the corresponding treatment also draws on the results of the clinical research and analysis of female breast cancer. The treatment principle of early male breast cancer is the same as that of female breast cancer: surgery is the main treatment, supplemented by chemotherapy, radiotherapy, endocrine therapy and other comprehensive treatment measures. 1. Surgery The breast size of male breast cancer patients in China is small, and the mass is easy to invade the pectoral muscle and metastasize to the inter-pectoral muscle and axillary lymph nodes, therefore, modified radical surgery can not completely replace the typical radical surgery. For patients whose lesions have invaded the pectoral muscle, typical radical surgery is the main surgical method; for those whose lesions have not yet invaded the pectoral muscle, modified radical surgery can be chosen. In addition, the staging of male breast cancer is often later than that of female patients, men do not have enough glandular tissue to delay the infiltration of the tumor into the periphery, and the tumor is located in the areola region, etc. This makes breast-conserving surgery inappropriate for most male breast cancer patients. However, some studies suggest that breast-conserving surgery is an option when the mass has not yet involved the nipple or areola and the patient has a large breast size. maraz et al. suggest that clinical consideration be given to performing sentinel lymph node biopsy in male breast cancer patients with negative axillary lymph nodes. 2. chemotherapy and radiotherapy A number of retrospective studies have shown that adjuvant chemotherapy can benefit patient survival, but there is a lack of prospective studies to support this. The choice of treatment regimen can be based on female breast cancer. Further studies are needed to determine whether the molecular staging of female breast cancer is also applicable to male breast cancer patients. Overseas studies have suggested that the indications for postoperative adjuvant radiotherapy in female breast cancer are also applicable to men, and that male breast cancer patients should receive radiotherapy more aggressively because of the higher rate of nipple and local skin invasion in men. In recent years, Madden et al. found that radiotherapy can improve the overall survival of male breast cancer patients in stage I, and there is a tendency to improve the survival rate of patients in stage II and III. 3. Endocrine therapy The proportion of sex hormone receptor positive male breast cancer patients is higher than that of female, and postoperative adjuvant endocrine therapy is the main treatment means. At present, endocrine therapy is preferred to oral tamoxifen treatment for 5 years. A study showed that among 116 male breast cancer patients with sex hormone receptor-positive breast cancer, the 5- and 10-year survival rates of patients who adhered to tamoxifen for 5 years after surgery were 97.9% and 79.6%, respectively, while those who did not adhere to it for 5 years were 84.7% and 50.4%. Reasons for non-adherence to medication include hot flashes, sexual dysfunction, decreased libido, weight gain, fatigue and bone pain. In sex hormone receptor-positive postmenopausal women with breast cancer, third-generation aromatase inhibitors have been shown to be more effective than tamoxifen. However, studies have also shown that third-generation aromatase inhibitors are less effective than tamoxifen in men with breast cancer. This is because 80% of estrogen in men is androgen converted in peripheral tissues by the enzyme aromatase; whereas 20% of estrogen is produced by the testes and is not dependent on aromatase. Some studies have suggested that third-generation aromatase inhibitors in combination with gonadotropin-releasing hormone inhibitors may improve efficacy in male breast cancer. A clinical study showed that 73.9% of hormone receptor positive metastatic male breast cancer patients benefited from treatment with Fulvestrant. 4. Targeted therapy Arslan et al. retrospectively analyzed the data of 118 non-metastatic male breast cancer patients and found that the disease-free survival of HER2-positive and negative patients was 52 and 120 months, and the overall survival was 85 and 144 months, suggesting that the prognosis of HER2-positive male breast cancer patients is as poor as that of HER2-positive female breast cancer patients. About 15% of male breast cancer patients have positive HER2 expression, and it has been reported that the use of trastuzumab in some advanced HER2-positive male breast cancer patients can alleviate symptoms and prolong survival. Prognosis of male breast cancer Prognostic factors of male breast cancer are similar to those of female, mainly related to tumor grading, tumor size, vascular embolism, margins, receptor status, axillary lymph node metastasis and so on. It has been reported that male breast cancer patients have a poorer prognosis with later staging at the time of first diagnosis. However, some studies have found that matching male and female breast cancer patients according to stage, age, and time of diagnosis showed that male breast cancer had a similar prognosis to female breast cancer patients. In conclusion, although the incidence rate of male breast cancer is low, the number of incidence patients is increasing year by year. Due to insufficient clinical attention to this disease, there is a phenomenon of missed diagnosis and treatment. The diagnosis is made at an older age, the staging is relatively late, and the prognosis is poorer. Therefore, we should strengthen the popularization of male breast cancer, pay attention to its high-risk groups, and perform regular breast examination, so that early diagnosis, early treatment and comprehensive treatment are the keys to improve the prognosis of male breast cancer.