métastases

Metastases are secondary tumors that arise when cancer cells spread from a primary site to distant organs. They result from cancer cells detaching, invading blood vessels or lymphatics, surviving circulation, and colonizing new tissue. The pattern of spread reflects both tumor biology and the vascular architecture of potential target organs.

Spread occurs mainly through the hematogenous route, lymphatic dissemination, or, less commonly, direct seeding across body cavities. The liver and lungs are frequent metastatic destinations because of their rich blood supply; bone is a common site for breast, prostate, and thyroid cancers; brain metastases occur with several malignancies, notably lung and breast cancer; peritoneal metastases arise with ovarian and gastrointestinal cancers.

Clinical presentation varies by location and extent. Some metastases cause organ dysfunction, pain, or neurologic symptoms, while others remain asymptomatic until discovered on imaging for other reasons. Diagnosis combines imaging studies (such as CT, MRI, or PET scans) with tissue biopsy and histopathology to confirm metastasis and identify the tissue of origin. Molecular and immunohistochemical analyses may guide treatment.

Staging classifies metastatic spread as stage IV in many cancers and informs prognosis and treatment planning. Management typically involves systemic therapies—such as chemotherapy, targeted therapy, or immunotherapy—aimed at controlling disease and prolonging survival, along with local treatments like surgery or radiotherapy to relieve symptoms or treat life-threatening lesions. The goal is palliation and improvement of quality of life, rather than cure in most advanced cases.