What Causes Lymphoma?
The cause of lymphoma is still a subject of much debate, and many lymphoma patients do not have obvious risk factors.
Epstein Barr and Herpes Viruses. The Epstein Barr virus is thought to cause one third of all HD cases (Jarrett RF 2003). In addition, HD patients often show high numbers of herpes-infected cells (Krueger GR et al 1994). These viruses are thought to contribute to the development of lymphoma (Krueger GR et al 1994), and are also linked to the development of NHL (Danese C et al 2004; Muller AM et al 2005).
Weakened Immune System. Individuals with suppressed immune systems associated with HIV infection appear to be at higher risk of developing HD (Lim ST et al 2005; Thompson LD et al 2004).
Factors that play a role in susceptibility to non-Hodgkin’s lymphoma include nutrition, medical history, environment, and use of medications.
Diet/Nutrition. NHL is more common in individuals with weakened immune systems (Zhang S et al 1999; Zhang SM et al 2000). Clinical studies have now shown that diets rich in animal protein and fats, which are thought to diminish immune function (Calder PC et al 2002; Jones DE 2005; Plat J et al 2005), are associated with an increased risk of developing NHL (Chang ET et al 2005; Chiu BC et al 1996; De SE et al 1998; Zhang S et al 1999). Clinical studies have also shown that diets rich in fruits and vegetables, which are thought to enhance immune cell function (Gaisbauer M et al 1990; Rossing N 1988; van LOGHEM JJ 1951), are associated with a reduced risk of developing NHL (Zhang SM et al 2000; Zheng T et al 2004).
Medical History. Evidence suggests that some medical conditions or procedures, especially those that reduce immune system activity, increase the risk of developing non-Hodgkin’s lymphoma. These include:
- Blood transfusions and organ transplantation
- Celiac disease
- Hepatitis C
- Epstein Barr virus
- Gastric ulcers (Helicobacter pylori)
- HTLV (human T-lymphotropic virus)
Numerous studies have examined the link between blood transfusions and the development of NHL. However, the data are conflicting, with some studies showing that allogeneic blood transfusions (i.e., from other people/donors) are associated with a twofold increase in the risk of developing NHL (Cerhan JR 1997a; Vamvakas EC 2000). Similarly, the risk of NHL is thought to increase in organ transplant patients (Vamvakas EC 2000), most likely as a result of post-transplant immunosuppression.
In older women, adult-onset (type II) diabetes of long duration has also been shown to increase the risk of developing NHL (Cerhan JR et al 1997b). Other clinical studies have also shown that diabetes sufferers are at greater risk of developing NHL (Natazuka T et al 1994), presumably because diabetes impairs the efficiency of the immune system (Jackson RM et al 1987; Kohn LD et al 2005).
Celiac disease, a condition characterized by inflammation of the intestinal lining due to sensitivity to a protein called gluten (found in wheat and rye), is also associated with increased risk of developing NHL, particularly localized in the gut (Catassi C et al 2002; Smedby KE et al 2005; Sonet A et al 2004).
Hepatitis C virus, a common infection in the US, is linked to the development of B-cell NHL (Fiorilli M et al 2003; Vallisa D et al 2005), MALT lymphoma (Seve P et al 2004), and a rare type of NHL known as primary hepatic lymphoma (Noronha V et al 2005). Interestingly, this association appears to have some geographical variations, although some studies do not support it (Giannoulis E et al 2004; Morgensztern D et al 2004).
Helicobacter pylori infection, normally associated with peptic ulcers, is also linked to the development of gastric MALT lymphomas (Franco M et al 2005; Wotherspoon AC 1998).
The immunosuppression caused by infection with the human immunodeficiency virus (HIV) is associated with a greater risk of developing NHL (Irwin D et al 1993; Kaplan LD 1990; Tulpule A et al 1999). The incidence of NHL in HIV-positive individuals is 60 times greater than that observed in the general population (Tulpule A et al 1999).
The human T-lymphotropic virus, a close relative of HIV, is also known to cause T-cell lymphomas (Nicot C 2005).
Environment. Exposure to pesticides and herbicides is associated with an increased risk of developing non-Hodgkin’s lymphoma, particularly in rural farming communities where these substances are used routinely (Quintana PJ et al 2004; Waddell BL et al 2001; Weisenburger DD 1990). Asthmatics exposed to pesticides have a higher risk of developing NHL compared to non-asthmatics (Lee WJ et al 2004). Chemicals known as dioxins, which are emitted from solid waste incinerators, are thought to increase the risk of non-Hodgkin’s lymphoma (Floret N et al 2003). Contamination of drinking water with nitrates is also thought to increase the risk of developing NHL (Ward MH et al 1996), though other studies show that contamination levels would have to be very high to pose this risk (Freedman DM et al 2000).
Medications. Long-term use of medications such as conventional hormone replacement therapy (primarily unopposed estrogens with synthetic, equine-derived estrogens), certain antibiotics, and pain relievers is associated with an increased risk of certain types of NHL (Cerhan JR et al 2002; Kato I et al 2002; Kato I et al 2003). In particular, individuals with rheumatoid arthritis who are long-term users of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) have a greater risk of developing NHL (Cerhan JR et al 2003).
What You Have Learned So Far
- Lymphomas are cancers of the lymphatic tissues that are involved in storage and distribution of infection- and tumor-fighting white blood cells.
- Because lymph tissue is found throughout the body, lymphoma can begin in almost any part of the body and spread to almost any tissue or organ.
- Risk factors linked to the development of lymphoma include diet, medical history, certain viruses, chemical exposure, and conditions that weaken the immune system.
- Swollen lymph nodes and weight loss are possible signs of lymphoma.
- Tests that examine the lymph nodes are used to detect and diagnose lymphoma.
- Medical treatment for lymphoma traditionally has been based on combinations of chemotherapy, radiotherapy, and stem cell therapy.
- Innovative treatments include radioimmunotherapy and chemoimmunotherapy.
- Nutritional supplements that can be used to complement conventional treatments include curcumin, genistein in soy extract, vitamins A, C, D, and E, green tea, resveratrol, ginger, fish oil, and garlic.