Several categories of risk
factors have been identified that are linked to an increased likelihood of
developing lymphoma. Having one or more of these risk factors does not
necessarily mean, however, that you will develop lymphoma. Risk factors are
merely attributes that have been associated with a statistically greater chance
of developing the disease.
Non-Hodgkin lymphoma (NHL) is
the fifth most common cancer, while Hodgkin lymphoma is relatively rare.
Elderly patients diagnosed with Hodgkin lymphoma tend to have a worse prognosis
than younger patients. Although NHL can strike at any age, advanced age is
associated with a somewhat greater risk of developing the disease. For
instance, people in their early 20s are afflicted with NHL at a rate of about 2.4
cases per 100,000 people. The incidence of the disease climbs to about 46 cases
per 100,000 among people in their early 60s. Men are afflicted more often than
women, and Caucasians are slightly more likely to develop lymphoma than Asian
Americans or African-Americans.
No specific hereditary or
genetic link has been identified, but people with a close family member who has
been diagnosed with NHL are slightly more likely to be diagnosed with NHL.
Certain infections have been
linked to an increased risk of NHL. Most of these cause diseases that affect
the immune system. They include human immunodeficiency virus (HIV),
Epstein-Barr virus, hepatitis B and C, and Helicobacter pylori infection.
HIV infection, the cause of
AIDS, is associated with an increased risk of high-grade lymphomas, including
Burkitt lymphoma and diffuse large B-cell lymphoma. The advent of AIDS has been
suggested as a possible explanation for the sharp increase in cases of
lymphomas since the 1970s. Although cases have nearly doubled since then,
advances in diagnosis and treatment have significantly improved prognosis.
Epstein-Barr virus, the cause
of mononucleosis (the “kissing disease”), is highly associated with NHLs such
as Burkitt lymphoma. Infection with the virus is also linked to an increased
risk of Hodgkin lymphoma.
The human herpes virus 8 (HHV8)
is capable of infecting lymphocytes, and has been linked to a rare type of
lymphoma most commonly found among people who are also infected with HIV.
Hepatitis B and hepatitis C are
viruses that attack the liver. Infection with hepatitis C has been linked to a
20 percent to 30 percent increase in the risk of NHL. People infected with
hepatitis B are about twice as likely to develop lymphoma as people who have
not been infected with the virus.
Helicobacter pylori is a
bacterium that lives in the digestive tracts of nearly two-thirds of people
around the world. Although a majority of people are evidently unaffected by the
bacteria, in some individuals, H. pylori infection causes peptic ulcers. H.
pylori is also a risk factor for a type of lymphoma known as gastric
mucosa-associated lymphoid tissue lymphoma (MALT).
Compromised Immune System
Any of a number of conditions
linked to a compromised immune system may also raise a person’s risk of
developing lymphoma. These include: HIV infection, autoimmune diseases, use of
drugs and other therapies to suppress the immune system, and hereditary
The HIV virus specifically
targets the immune system, including lymphocytes called T cells. The emergence
and spread of HIV in the early 1980s is believed to account for a near doubling
in cases of lymphoma since the 1970s.
Autoimmune diseases occur when
the immune system mistakenly attacks the body’s own tissues. Examples include
rheumatoid arthritis, systemic lupus erythematous and, type 1 diabetes.
Evidence suggests a strong link between some autoimmune diseases and risk of
Immune system suppression,
primarily used to prevent tissue rejection after organ transplant, is
associated with an increased risk of developing lymphoma. Intensive
immunosuppressive therapy, with modern immunity suppressing drugs, is a major
risk factor for so-called lymphoproliferative disorders, including lymphoma.
affects the viability of the body’s immune system. One of the most dramatic
examples is severe combined immunodeficiency (SCID), also known as the “bubble
boy” disease, so named for the well-publicized case of a victim who survived
for 12 years by living in an isolated, sterile environment. Patients with these
disorders are at increased risk of developing lymphoma.
Scientists are presently
examining the issue of toxins and lymphoma risk. Exposure to certain toxins—including
pesticides, herbicides and environmental carcinogens—have all been linked to an
increased risk of lymphoma. Carcinogenic chemicals such as benzene may also
increase risk. Certain drugs used to treat other cancers have also been linked
to an increased risk of NHL. Ironically, patients who receive chemotherapy to
combat Hodgkin lymphoma are at increased risk for subsequently developing NHL.
Radiation is classified as a
carcinogen, and radiation exposure has been linked to an increased risk of NHL.
Radiation exposure, even from common sources such as diagnostic X-rays, is
cumulative. On average, Americans are exposed to seven times more radiation now
that they were in the 1980s, primarily due to the growing use (some would argue,
overuse) of modern computerized tomography (CT) scanners. A report published in
2007 in the New England Journal of
Medicine estimates that CT scans may account for up to 2 percent of new
cases of cancer in the United States.