Family Health Matters. Cancer Care Widens Its Reach. Detecting Colorectal Cancer. Editor: Harrison Wein, Ph. Managing Editor: Tianna Hicklin, Ph. Illustrator: Alan Defibaugh. Attention Editors: Reprint our articles and illustrations in your own publication. But cancer that is thought to be cured can still come back even years later. This is why some doctors prefer to say that the cancer is in remission. Remission means there are fewer signs and symptoms of a disease such as cancer or that they have completely gone away.
Home Cancer information What is cancer? How cancer starts, grows and spreads. See topics What is cancer? Types of cancer Human body Immune system Lymphatic system Blood and bone marrow Endocrine system and hormones Female sex organs and reproductive system Male sex organs and reproductive system How cancer starts, grows and spreads Types of tumours Genes and cancer Stage and grade Prognosis and survival What causes cancer?
What is cancer? Diagram of cell division. Diagram of how cancer grows. Diagram of how cancer spreads. Where cancer can spread and staging. Why does cancer sometimes come back? Cure or remission. References American Society of Clinical Oncology.
Although cancer is not contagious, there are some situations that can make people think that cancer has spread from one person to another. Although cancer itself is not contagious, there are some germs that can play a role in the development of certain types of cancer.
If cancer were contagious, we would have cancer outbreaks just as we do with the flu. We would expect a high rate of cancer among the families and friends of people with cancer and among health professionals who care for them. This is not the case. The circulatory system is the primary route of spread to distant organs, while lymphatic vessels provide a route to local lymph nodes , after which metastases often travel through the blood 4 While the circulatory system appears to be the most common route, the extent of lymphatic versus hematogenous spread appears to depend on the origin and location of the primary tumor.
In order for tumor cells to gain access to lymphatic or blood vessels, tumors need to promote the growth of these vessels into and around the tumor. Growth of blood vessels is called angiogenesis, and growth of lymphatic vessels is lymphangiogenesis. Learn more about angiogenesis. The Lymphatic System The lymphatic system plays an important role in controlling the movement of fluid throughout the body.
There are some similarities and differences between the more well known circulatory system and the lymphatic system. Small lymphatic vessels merge into larger ones and these large vessels eventually empty into lymph nodes.
Lymph nodes are kidney bean shaped tissues that are found in grape-like clusters in several locations around the body. Lymph nodes are sites of immune system activation and immune cell proliferation growth. The fluid in this extensive network flows throughout the body, much like the blood supply. It is the movement of cancer cells into the lymphatic system, specifically the lymph nodes, that is used in the detection of metastatic disease. The staging of cancer is discussed in more detail in the Diagnosis and Detection section.
The Anatomic Model In the anatomic model of metastsis, secondary tumors occur in the organs which they encounter first during their dissemination from the primary tumor. This scenario appears to occur in regional metastases, where tumor cells gain access to nearby tissue or lymph nodes through the blood or lymphatic circulation.
In this case, the capillary bed of the liver is the first encountered by the tumor cells after leaving the colon, and the liver seems to provide a suitable environment for the growth of these secondary tumors. The Seed and Soil Hypothesis Early cancer researchers noticed a propensity for certain cancers to metastasize to the same organ.
In Stephen Paget observed that patients with breast cancer often developed secondary tumors in the liver. He considered it unlikely that this occurrence was due primarily to accessibility of the liver by the blood supply, as other organs receiving equivalent blood supply rarely developed metastases.
He instead developed the "Seed and Soil" hypothesis, in which certain tumor cells the seeds can only successfully colonize selective organs the soil that have suitable growth environments At the heart of the Seed and Soil hypothesis is the idea that successful metastasis depends on the interaction of the metastasizing tumor cells with the cells of the target organ the stroma, or tumor microenvironment.
Not only must tumor cells must be able to produce factors that alter the stromal cells in such a way as to better serve the survival and growth of the tumor, but the environment in which the cancer cell finds itself must be capable of responding to those signals.
If the cancer cell finds itself in an inhospitable soil i. Recent studies examining the profile of genes expressed in tumors that metastasis to specific organs have identified specific genetic signatures of these tumors.
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