Signs and symptoms

The first symptom, or subjective sign, of breast cancer is typically a lump that feels different than the surrounding breast tissue. According to the Merck Manual, more than 80% of breast cancer cases are discovered when the woman feels a lump. According to the American Cancer Society (ACS), the first medical sign, or objective indication of breast cancer as detected by a physician, is discovered by mammogram. Lumps found in lymph nodes located in the armpits and/or collarbone can also indicate breast cancer.

The primary risk factors that have been identified are sex, age, childbearing, hormones, a high-fat diet, alcohol intake, obesity, and environmental factors such as tobacco use, radiation and shiftwork. No etiology is known for 95% of breast cancer cases, while approximately 5% of new breast cancers are attributable to hereditary syndromes.

Prevention

Lower age of first childbirth (less than 24 years maternal age), having more children (about 7% lowered risk per child), and breastfeeding (4% per breastfeeding year, with an average relative risk around 0.7.