Researchers found that men who use cocaine are twice as likely as abstainers to develop intermediate- or high-grade non-Hodgkin’s lymphoma (NHL). For those who use cocaine more frequently, ie, on at least nine occasions, the risk is more than triple what nonusers face, says Rebecca Nelson, a doctoral student in the preventive medicine department at the University of Southern California (USC) School of Medicine, in an article published recently in the British Journal of Cancer.
Coauthors of the study were USC School of Medicine faculty members Leslie Bernstein, PhD, professor of preventive medicine; Alexandra Levine, MD, professor and chief of hematology; and Gary Marks, MD, associated professor of preventive medicine.
In 1994, 45,000 people in the US were diagnosed with NHL; roughly half of all NHL patients survive 5 years or more.
Researchers studied 378 Los Angeles residents diagnosed with NHL. The patients, 18 to 75 years old, were matched with healthy controls of the same age, ethnicity, gender, and social background. All patients and controls tested negative for the AIDS virus, HIV-1. Researchers asked patients and controls about their use of tobacco, alcohol, and 10 recreational drugs, including cocaine, marijuana, heroin, amphetamines, barbiturates, Quaaludes, LSD, PCP, “magic mushrooms,” and “poppers,” such as butyl and amyl nitrates.
“In general, the patients used more drugs than controls, but less alcohol,” Dr. Bernstein says. Researchers also found that men reported using drugs much more often than women did. After taking other factors, such as past medical history, into account, researchers found the link between cocaine and cancer.
“We saw a similar increased risk for the cancer in women using cocaine, but there were so few female drug-takers in the study that it’s impossible to draw any conclusions,” Nelson says.
First Link Between Cocaine and Cancer
This is the first time anyone has found a link between cocaine and cancer, says Dr. Bernstein. The authors speculate that cocaine may stimulate white blood cell activity and growth, thereby speeding up the propagation of chance genetic errors that could lead to cancer.
Dr. Bernstein notes, however, that the study needs to be repeated before scientists can say with any certainty whether cocaine itself triggers the disease or whether some other unknown factors play a role.
In any case, cocaine use alone cannot fully explain the steady rise in NHL cases over the last 30 years. Between 1973 and 1991, there was a 70% increase in the incidence of the disease. While some of that increase has been tied to the AIDS epidemic—HIV-positive patients face 60 times the risk of developing NHL as the general population—evidence shows that AIDS does not account for most of this trend.
A weakened immune system is known to render people at higher risk of NHL. Researchers have also found links between certain herbicides, such as 2,4-D, and NHL. Others are investigating Epstein-Barr virus.
“In many ways,” says Dr. Bernstein, “epidemiologists are just beginning to unravel the complex pattern of risk factors for this disease.”