What is the most common type of breast cancer diagnosed in women in the United States?

Infiltrating ductal carcinoma is identified as the most common type of breast cancer diagnosed in women in the United States. This cancer originates in the milk ducts of the breast and then invades the surrounding breast tissue. It accounts for the majority of breast cancer cases, with estimates indicating that it makes up approximately 70-80% of all breast cancers.

The predominance of infiltrating ductal carcinoma is attributable to its characteristics, which can include its aggressive behavior and the potential for early metastasis. The diagnosis is typically made through imaging studies such as mammography, followed by biopsy to confirm the presence of cancerous cells.

Other types of breast cancer, such as infiltrating lobular carcinoma, Paget's disease of the nipple, and medullary carcinoma, are less common. Infiltrating lobular carcinoma, while significant, occurs with a lower frequency and has distinct pathological features compared to ductal carcinoma. Paget's disease primarily affects the nipple and is associated with underlying ductal carcinoma but is not a predominant form of breast cancer itself. Medullary carcinoma is a rarer subtype that may show better prognosis due to its well-circumscribed nature, but its incidence is lower in the overall breast cancer population.