Male breast cancer is clinically rare, accounting for <1% of all breast cancers and <1% of malignant tumors in men. Because of its lower incidence and gender-specific features, it is often overlooked by patients and physicians. Compared with female breast cancer, male breast cancer is characterized by older age of onset, higher pathological malignancy and higher mortality rate. In recent years, as the incidence of male breast cancer increases, it is gradually attracting people's attention. Risk factors 1. Genetic factors: Some studies have shown that family history of breast cancer increases the incidence of MBC by about 2.5 times, and about 20% of the first-degree relatives of MBC patients will develop breast cancer. Genetic susceptibility is highly correlated with breast cancer susceptibility gene1 and BRCA2 variants, among which BRCA2 variants are common. In addition, cell cycle checkpoint kinase 2 gene, androgen receptor-encoding gene and cytochrome P45017 enzyme gene, thymus cell selection-related high migration rate clade 3 gene and DNA repair gene also increase the risk of MBC. Endocrine factors: The main reason for the low incidence of MBC is that the estrogen level in men is lower than that in women, so the use of estrogen therapy in prostate cancer patients may increase the risk of MBC. In addition, other diseases that lead to lower androgen levels in the body, such as obesity, cryptorchidism, congenital inguinal hernia, orchitis, hepatic sclerosis, and adult mumps, are also risk factors for MBC. 3. Occupational factors: Long-term exposure to radiation increases the incidence of breast cancer in women, which also increases the incidence of MBC. In addition, paper workers, painters and furniture workers have a higher risk of male breast cancer, which may be related to the work environment rich in alkyl phenolic compounds that can cause hormonal disorders in the body. Men who are exposed to high temperature for a long period of time are also at increased risk of MBC because of testicular dysfunction. The most common clinical manifestation of MBC is a painless mass under the areola, accompanied by nipple depression, blood or fluid overflow, often accompanied by other malignant tumors, with prostate cancer and bladder cancer being the most common. Pathological features The most common pathological type is invasive ductal carcinoma, followed by ductal carcinoma in situ, and lobular carcinoma in situ is rare. Among them, invasive ductal carcinoma cells have low differentiation, large cell heterogeneity, increased nuclear division phase, and often appear pathological nuclear division phase, so the tumor malignancy is higher. Treatment At present, there is no standard treatment plan for MBC in the international arena, and surgery is still the preferred method. Surgery is still the first choice. Postoperative treatment is supplemented by radiotherapy, chemotherapy, endocrine therapy and targeted therapy according to the patient's symptoms, pathological type, hormone receptor status, infiltrative metastasis and general condition. In male breast cancer patients, ER and PR are highly expressed, and the most commonly used endocrine therapy drug is tamoxifen. V. Prognosis Compared with women, male breast cancer patients have a poorer prognosis, which may be related to the older age of MBC patients, higher pathological malignancy and often concomitant other diseases. The most definite prognostic factors are the size of the tumor and the presence or absence of axillary lymph node invasion at the time of diagnosis. The risk of death is 40% higher for tumors with a maximum diameter between 2 and 5 cm than for those with a maximum diameter less than 2 cm, and 50% higher for those with lymph node metastasis than for those without.