Structural and Functional Basis
To understand the localization of pathological processes, basic anatomy is essential. The mammary gland consists of 15–20 lobes separated by adipose tissue and fibrous septa.
The main structural and functional unit is the terminal duct lobular unit (TDLU). It is located within the loose interlobular stroma and consists of a terminal duct with branching alveoli and acini.
Normally, the ducts and alveoli are lined by two layers of cells:
- Cuboidal epithelium (inner layer).
- Myoepithelial cells (outer layer).
Hyperplastic and neoplastic processes most frequently originate from the epithelial elements of this terminal unit.
Conditions Increasing Cancer Risk
The development of invasive cancer is often preceded by background and precancerous tissue changes.
Fibrocystic Changes This is the most common pathology, diagnosed in over 10% of women aged 35–40. Macroscopically, it presents as painful nodules. If the process is accompanied by atypical epithelial hyperplasia (formation of multi-layered solid, cribriform, or papillary structures), it is officially considered a precancerous condition.
Radial Scar A stellate sclerosing lesion characterized by a central zone of hyalinized collagen and obliterated ducts, surrounded by hyperplastic tubular structures. It can macroscopically mimic cancer and serves as a potential source of malignancy (risk depends on the degree of dysplasia).
Intraductal Papilloma Papillary growths within the ducts, typically manifesting as bloody nipple discharge. Single papillomas carry a favorable prognosis, whereas multiple lesions (frequently seen in younger women) increase the risk of cancer development by 4–6 times.
Epidemiology and Risk Factors
Breast cancer (Carcinoma mammae) is more prevalent in high-income countries, where it accounts for over 26% of female malignancies. Tumor development is multifactorial, but fundamentally driven by hyperestrogenism.
Risk-enhancing factors:
- Prolonged reproductive lifespan (early menarche and late menopause).
- Nulliparity or first full-term pregnancy after age 30.
- Exogenous estrogen therapy.
- Presence of hormonally active tumors (e.g., estrogen-synthesizing granulosa cell tumors or thecomas of the ovary).
Protective factors:
- Early pregnancy and childbirth.
- Prolonged and exclusive breastfeeding.
The "Western Lifestyle" Concept
According to WHO frameworks, specific lifestyle factors directly influence breast cancer risk. This involves a combination of a high-calorie diet (rich in fats and proteins) and low physical activity, inevitably leading to obesity and insulin resistance.
Pathogenetic mechanism:
- Hyperinsulinemia develops alongside elevated levels of insulin-like growth factor (IGF).
- Peripheral estrogen synthesis is upregulated in adipose tissue.
- Sex hormone-binding globulin (SHBG) levels decrease.
- Result: A sharp increase in free (bioavailable) estrogen in the blood plasma, which continuously stimulates epithelial proliferation within the breast tissue.