Malignancy

 The tumor–node–metastasis (TNM) staging system used for many solid tumors considers the tumor size and degree of local invasion (T), the amount , size, and site of lymph nodes (N), and therefore the presence or absence of distant metastases (M). Metastases of tumors originating in several sites, like the breast or lung, are treated differently because they're thought to behave just like the tissue of origin, with characteristic patterns and kinetics of spread, and distinct profiles of chemosensitivity. Lymph nodes are of paramount importance in current staging practices, but it's hard to interpret the clinical significance of the space of metastases from the first site (e.g., a supraclavicular N3 vs. a mediastinal N2 lymph gland in lung cancer). Indeed, the space from the first tumor to the organ of metastasis doesn't affect staging. For this reason, the important value of staging is to function an indicator of the first cancer’s composite capability to metastasize, instead of to make sure that the tumor lies within the prescribed limits of an area intervention. Recent advances bring hope for characterizing the metastatic behavior of cancer cells beyond the simplistic TNM stage. within the future, staging could include identification of subpopulations of tumor cells that have different metastatic behavior. A deeper understanding of the molecular and genetic concepts and processes involved in metastasis may pave the way toward new prognostic models and ways of designing treatment.