What Is Breast Cancer?
Breast cancer is the uncontrolled proliferation of abnormal cells originating in breast tissue. It is the most commonly diagnosed cancer in women globally (approximately 2.3 million new cases annually) and can also occur in men. The vast majority originate in the ductal or lobular epithelium. Most breast cancers are not hereditary — approximately 10–15% are attributable to identifiable genetic mutations (primarily BRCA1 and BRCA2); the remainder occur sporadically.
Types of Breast Cancer
Invasive ductal carcinoma (IDC) accounts for approximately 80% of breast cancers — originating in the ductal epithelium and invading surrounding tissue. Invasive lobular carcinoma (ILC) accounts for approximately 10–15%, originating in the lobules and often presenting without a discrete lump. Ductal carcinoma in situ (DCIS) is a non-invasive pre-cancerous condition confined to the ductal lumen. Less common types include inflammatory breast cancer, triple-negative breast cancer, and HER2-positive breast cancer.
Risk Factors
Risk factors include: increasing age, female sex, BRCA1/2 mutations, personal or family history of breast cancer, early menarche, late menopause, nulliparity or late first pregnancy, long-term hormone replacement therapy, high breast density, obesity (particularly post-menopause), alcohol consumption, and prior chest radiation therapy. Most people with risk factors do not develop breast cancer; most who develop breast cancer have no known specific risk factors.
Breast Implants and Cancer Risk
Standard silicone and saline breast implants are not associated with increased risk of standard breast cancer types. Multiple large studies have confirmed this. The exception is BIA-ALCL (Breast Implant-Associated Anaplastic Large Cell Lymphoma) — a lymphoma associated specifically with textured implants that is not a breast carcinoma but a lymphoma arising in the capsule. Breast implants do not cause breast carcinoma.
