malignancy

Malignancy is a property of certain neoplasms in which cells acquire the ability to invade adjacent tissues and to spread (metastasize) to distant sites. Malignant tumors, or cancers, contrast with benign neoplasms that remain localized. Malignancies can arise in virtually any tissue and are classified by cell type and tissue origin, such as carcinomas (epithelial), sarcomas (mesenchymal), leukemias, lymphomas, and gliomas.

Malignancy results from cumulative genetic and epigenetic changes that disrupt normal cell regulation. Common features include sustained proliferative signaling, evasion of growth suppression, resistance to cell death, replicative immortality, induction of angiogenesis, and the ability to invade surrounding tissue and disseminate. Cancer cells may also exhibit genomic instability and immune evasion. These alterations accumulate through somatic mutations, environmental exposures, and inherited predispositions, leading to heterogeneous tumor behavior and responses to therapy.

Diagnosis typically involves biopsy with histopathologic examination, often complemented by imaging and laboratory tests. Staging uses criteria such as the TNM system to assess tumor size, nodal involvement, and metastasis, guiding treatment decisions. Risk factors include tobacco use, excessive alcohol, obesity, infections (for example, certain viruses), radiation exposure, and environmental carcinogens. Prevention focuses on risk reduction, vaccination, screening programs, and lifestyle modification.

Treatment is usually multidisciplinary and tailored to tumor type and stage. Main modalities include surgery to remove tumors, radiotherapy, and systemic therapies such as chemotherapy, targeted therapies, immunotherapies, and hormone therapies. Early-stage cancers may be curable, while advanced disease commonly aims to control growth and palliate symptoms. Prognosis depends on cancer type, stage at diagnosis, molecular characteristics, patient health, and response to therapy, with survival improving in many cancers through prompt detection and advances in treatment.