Pathophysiology and Diagnosis
Breasts, or mammary glands, function to produce milk. Breast tissue is composed of ducts and lobules contained in fatty tissue.
The development of all cancers, including breast cancer, occurs at the cellular level. It is a complex phenomenon between cellular proliferationand regression that normally occurs in the breast. These changes are influenced by hormones—primarily estrogen and progesterone—and growth factors. Briefly, the continuum of normal and abnormal changes is summarized here (ACS 2013):
NORMAL cell cycles of proliferation and regression are controlled by hormones and growth factors.
ABNORMAL cellular changes progress from proliferative disease→atypical hyperplasia→carcinoma in situ→invasive breast cancer.
ABNORMAL varied histology prohibits describing carcinogenesis by a single pathway. Instead, breast cancer may develop as a result of:
Alterations in several of 200 genes
A single gene alteration that affects many cell functions
The definitive diagnosis of breast cancer is made by biopsy.