Mechanisms of development (pathogenesis) of breast cancer

Almost all breast cancers arise from glandular epithelial cells lining the alveolar and lobular milk ducts, and therefore are typical adenocarcinomas. True, during screening, real in situ ductal carcinomas in situ (DCIS) are especially often found. Most primary cancers invade the stroma of the gland (invasive carcinoma) at the time of diagnosis.

The overwhelming majority of tumors are dense neoplasms located inside the gland, sometimes by the time the diagnosis is made, ulceration of the skin is observed, and the tumor becomes infiltrating. With a small lesion of the skin, wrinkling or retraction of the skin is observed, with infiltration of the skin by a tumor, local lymphatic ducts obstruct and an orange peel develops.

Tumors are highly polymorphic, and their classification is based on microscopic data. Recently, histochemical dyes have been widely used. The stage of tumor development, and especially the degree of its differentiation, is of great prognostic value.

Obviously, non-invasive carcinoma of the milk ducts (DCIS and lobular structures in situ) is a precancerous change. Sometimes it is accompanied by the development of various anomalies of the breast. Since mass screening studies have become widespread, DCIS has become more often diagnosed. In fact, true duct carcinoma is correctly called the “new disease”. The nature of this tumor is not completely clear, however, radiation and tamoxifen reduce the risk of its transition to an invasive form.

Pathways of mammary gland tumors have been the subject of discussion. The answer to the question was clarified: does breast cancer always spread “radially” or through the lymphatic system, and then the bloodstream is actively involved in the pathological process, or is the hematogenous pathway realized even without the involvement of regional lymph nodes? Currently, it is known that metastases of hematogenous origin, indeed, can be formed independently, however, the defeat of the axillary lymph nodes indicates a high probability of hematogenous spread of the tumor.