Lymphoma cancers develop in cells of the immune system or in cells of the lymphatic system. They are classified as Hodgkin's or non-Hodgkin's lymphomas and whether they are slow-growing or aggressive. More than 10 different types of non-Hodgkin’s lymphomas exist. The National Cancer Institute or NCI reports that the age-adjusted incidence rate for lymphoma is 22.4 per 100,000 men and women per year. The NCI also notes that the overall five-year survival of people with lymphoma is 70 percent.
The lymphatic system is composed of a network of interconnected nodes and vessels that transport fluids and nutrients and immune system cells. The thymus and bone marrow are involved in synthesis or maturation of the cells of the immune system that are transported by the lymphatic system. Lymphomas can develop in multiple different types of white blood cells and because they are within the lymphatic system the tumor cells can spread from one lymph node to another via lymphatic vessels. The NCI reports that people with lymphoma often have non-localized cancer in which tumor cells have moved to other parts of the lymphatic system.
The lymphoma-derived tumor cells transported in the lymphatic system need not be malignant. This contrasts with other solid tumors, because these tumor cells must transform into malignant cells to be transported to distant sites. Malignant cells are cancer cells that have acquired more mutations, allowing them to invade blood vessels and other tissues.
Metastasis is the process by which malignant cancer cells from a primary tumor spread to another site. In this process, tumor cells are shed from the primary tumor and move into blood or lymphatic vessels. The tumor cells are transported to other areas in the body where they invade other tissues. The NCI reports that the lungs, bones, liver, and brain are the most common sites of metastasis. Although it is rare, lymphomas can transform into malignant tumors and metastasize, or spread to other organs not in the lymphatic system.
Staging of Lymphomas
Lymphomas are categorized into four different stages, which characterize how far the cancer has spread in the body. According to the website eHealthMD, the four stages of lymphoma are the following; stage one refers to lymphomas that are localized to one lymph node or one non-lymphatic site; stage two lymphomas may have spread to two or more lymph nodes that are on the same side of the diaphragm, which separates the body into the thoracic and head region and the abdomen and legs; stage three lymphomas have spread to lymph nodes on both sides of the diaphragm or may have a second tumor in a non-lymphatic site; stage four lymphomas have spread diffusely in lymph nodes and to one or more other organ or tissue.
The intensity of treatment of lymphomas is dependent on the stage that it is classified and whether it is slow-growing or aggressive. The website Health Central purports that patients with slow-growing stage one and two lymphomas may carefully be monitored for symptom onset or treated with chemotherapy and radiation therapy or newer biological therapies. The same type of watchful waiting prior to starting treatment is recommended for slow-growing stage three and four lymphomas. However, after the onset of symptoms in people with these lymphoma types or those with fast-growing stage three and four lymphomas, they are aggressively treated with combination chemotherapy, immunological agents, radiation and possible bone marrow or stem cell transplantation.