ABSTRACT
Breast cancer is the most common cancer in women. Death from breast cancer has steadily declined since 1989—a trend attributable to a combination of early detection and advancements in treatment. A variety of hormones—including estrogen, progesterone, insulin, and growth factors—contribute to breast tissue development in utero and during puberty, pregnancy, and lactation. More recently, breast tumors have been subtyped based on histological characteristics and molecular profiling as these inform more directly on treatment approaches. Noninvasive breast cancers include ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). There are several risk factors for breast cancer including age, family history, and prior breast biopsy, especially when atypical hyperplasia is identified. Genetic breast cancer, in which one dominant cancer gene is passed on to future generations, accounts for only 5"–10" of all breast cancer cases. Most women treated with breast-conserving surgery will also receive follow-up treatment with radiation therapy (RT).
