Malignant Lymphoma Health Article

Definition

Lymphomas are a group of cancers in which cells of the lymphatic system become abnormal and start to grow uncontrollably. Because there is lymph tissue in many parts of the body, lymphomas can start in almost any organ of the body.

Description

The lymphatic system is made up of ducts or tubules that carry lymph to all parts of the body. Lymph is a milky fluid that contains lymphocytes. These, along with monocytes and granulocytes make up the leukocytes, or white blood cells, the infection-fighting and reparative bodies in the blood. Small pea-shaped organs found along the network of lymph vessels are called lymph nodes; their main function is to make and store lymphocytes. Clusters of lymph nodes are found in the pelvic region, underarm, neck, chest, and abdomen. The spleen (an organ in the upper abdomen), the tonsils, and the thymus (a small organ beneath the breastbone) are also part of the lymphatic system. Lymphocytes are held within the lymphoid tissue until they join the flow of lymph through the node. There are two main types of lymphocytes: the T cell and the B cell. Lymphomas develop from these two types. B-cell lymphomas are more common among adults, while among children, the incidence of T- and B-cell lymphomas are almost equal.

The T and the B cells perform different jobs within the immune system. When an infectious bacterium enters the body, the B cells make proteins called antibodies, which attach themselves to the bacteria, and flag them for destruction by other immune cells. The T cells help protect the body against viruses. When a virus enters a cell, it generally produces certain proteins that it projects onto the surface of the infected cell. T cells recognize these proteins and produce cytokines to destroy the infected cells. Some cytokines attract other cell types, which can digest the virus-infected cell. T cells can also destroy some types of cancer cells.

Lymphomas can be divided into two main types: Hodgkin's and non-Hodgkin's. There are at least 10 types of non-Hodgkin's lymphomas that are grouped (staged) by how aggressively they grow: slow growing (low grade), intermediate growing, and rapidly growing (high grade); and how far they spread.

Most non-Hodgkin's lymphomas begin in the lymph nodes; about 20% start in other organs, such as the lungs, liver or gastrointestinal tract. When lymphomas begin, malignant lymphocytes multiply uncontrollably and do not perform their normal functions, which affects the body's ability to fight infections. In addition, malignant cells may crowd the bone marrow, and, depending on the stage, prevent the production of normal red blood cells, white blood cells, and platelets. A low red blood cell count causes anemia, while a reduction in the number of platelets makes the person susceptible to excessive bleeding. Cancerous cells can also invade other organs through the circulatory system of the lymph, causing those organs to malfunction.

Causes & symptoms

The exact cause of non-Hodgkin's lymphomas is unknown. In general, males are at a higher risk than females, and the risk increases with age. Though it can strike people as young as 40, people between the ages of 60 and 69 are at the highest risk. In addition, the number of non-Hodgkin's cases has increased significantly in recent years, many of them due to the AIDS epidemic. (For reasons that are still poorly understood, AIDS patients have a higher likelihood of developing non-Hodgkin's lymphomas.)

People exposed to certain pesticides and ionizing radiation have a higher-than-average chance of developing this disease. For example, an increased incidence of lymphomas has been seen in survivors of the atomic bomb explosion in Hiroshima, and in people who have under-gone aggressive radiation therapy. People who suffer from immune-deficient disorders, as well as those who have been treated with immune-suppressive drugs for heart or kidney transplants, and for conditions such as rheumatoid arthritis and autoimmune diseases, are at an increased risk for this disease. Some studies have shown a loose association between retroviruses, such as HTLV-I, and some rare forms of lymphoma. The Epstein-Barr virus has been linked to Burkitt's lymphoma in African countries. However, a direct cause- and-effect relationship has not been established.

The symptoms of lymphomas are often vague and nonspecific. Patients may experience loss of appetite, weight loss, nausea, vomiting, abdominal discomfort, and indigestion. The patient may complain of a feeling of fullness, which is a result of enlarged lymph nodes in the abdomen. Pressure or pain in the lower back is another symptom. In the advanced stages, the patient may have bone pain, headaches, constant coughing, and abnormal pressure and congestion in the face, neck, and upper chest. Some may have fevers and night sweats. In most cases, patients go to the doctor because of the presence of swollen glands in the neck, armpits, or groin area. Since all the symptoms are common to many other illnesses, it is essential to seek medical attention if any of the conditions persist for two weeks or more. Only a qualified physician can correctly diagnose if the symptoms are due to lymphoma or some other ailment.