Breast cancer is the most common cancer among the Women that develops from breast tissue.Risk factors for developing breast cancer include obesity, a lack of physical exercise, alcoholism, hormone replacement therapy during menopause, ionizing radiation, an early age at first menstruation, having children late in life or not at all, older age, having a prior history of breast cancer, and a family history of breast cancer. About 5–10% of cases are the result of an inherited genetic predisposition, including BRCA mutations among others.

Breast Cancer Screening is usually done at the age of 40 to 70 years of age, and the organization recommends screening every two years in women 50 to 74 years of age. The medications tamoxifen or raloxifene may be used in an effort to prevent breast cancer in those who are at high risk of developing it. Surgical removal of both breasts is another preventive measure in some high risk women.

If all adults maintained the healthiest possible lifestyles, including not drinking alcoholic beverages, maintaining a healthy body composition, never smoking, eating healthful food, and other actions, then almost a quarter of breast cancer cases worldwide could be prevented. The remaining three-quarters of breast cancer cases cannot be prevented through lifestyle changes.

Breast cancer most commonly develops in cells from the lining of milk ducts and the lobules that supply these ducts with milk. Cancers developing from the ducts are known as ductal carcinomas, while those developing from lobules are known as lobular carcinomas. There are more sub-types of breast cancer. Some, such as ductal carcinoma in situ, develop from pre-invasive lesions. The diagnosis of breast cancer is confirmed by taking a biopsy of the concerning tissue. Once the diagnosis is made, further tests are done to determine if the cancer has spread beyond the breast and which treatments are most likely to be effective.

Breast cancer showing an inverted nipple, lump, and skin dimpling: signs of possible breast cancer

Breast cancer most commonly presents as a lump that feels different from the rest of the breast tissue. More than 80% of cases are discovered when a person detects such a lump with the fingertips. The earliest breast cancers, however, are detected by a mammogram. Lumps found in lymph nodes located in the armpits may also indicate breast cancer.

Indications of breast cancer other than a lump may include thickening different from the other breast tissue, one breast becoming larger or lower, a nipple changing position or shape or becoming inverted, skin puckering or dimpling, a rash on or around a nipple, discharge from nipple/s, constant pain in part of the breast or armpit and swelling beneath the armpit or around the collarbone. Pain (“mastodynia“) is an unreliable tool in determining the presence or absence of breast cancer, but may be indicative of other breast health issues.

In those with distant spread of the disease, there may be bone pain, swollen lymph nodes, shortness of breath, or yellow skin.

In those who have been diagnosed with cancer, a number of treatments may be used, including surgery, radiation therapy, chemotherapy, hormonal therapy, and targeted therapy. Types of surgery vary from breast-conserving surgery to mastectomy. Breast reconstruction may take place at the time of surgery or at a later date. In those in whom the cancer has spread to other parts of the body, treatments are mostly aimed at improving quality of life and comfort.

Outcomes for breast cancer vary depending on the cancer type, the extent of disease, and the person’s performance status. Worldwide, breast cancer is the leading type of cancer in women, accounting for 25% of all cases. In 2018, it resulted in 2 million new cases and 627,000 deaths. It is more common in developed countries and is more than 100 times more common in women than in men.