Cancers can either grow locally, in their site of origin, or spread via the bloodstream or Lymphatic channels to a distant site. Most cancers have a unique pattern of spread, which is discussed in each individual cancer, and is a guideline in planning a staging work up . Cancer cells, as they grow and form a mass or tumor, produce chemicals that stimulate production of blood vessels in nearby tissues, as well as inside the cancer tissue itself.
Cancer cells have the ability to break into the blood vessels and travel to distant sites.
Cells traveling in the blood become dislodged in another organ, i.e., brain or bone, etc. There they can grow and form another tumor. Some organs in the body have a greater tendency to accept metastasis than other tissues. Bones , lungs and brain are frequently among these. Spleen, kidneys and heart are among the organs which rarely accept metastasis.