Venezuela's president has mused that the US may have given him and other leftist leaders cancer. That's unlikely to be possible

Five South American presidents and former presidents, including Venezuela’s Hugo Chavez, have been recently diagnosed with cancer. Chavez speculated that US agents may be inducing the disease in South American leaders by feeding them or injecting them with an unspecified substance. The state department has rejected Chavez’s insinuation.

Can you give someone cancer? Not reliably. Injecting cancerous cells into a person isn’t enough to give him the disease. The abnormal tissue has to penetrate and grow in other areas of the body. If you injected someone with live cancer cells, their immune system would almost certainly attack and destroy the foreign tissue. In theory, secret agents might be able to induce cancer in a leftist South American president with a severely weakened immune system. Or perhaps they could harvest tissue from him, expose it to a carcinogen, and then reintroduce it into his body. As far as we know, however, these techniques have never successfully caused cancer in a human.

While it’s tough to induce cancer in an enemy, it’s certainly possible to increase his chances of developing the disease. The most effective option would be radiation. Oncologists implant radiation-emitting devices the size of a seed into some patients to combat existing cancers. It’s hard to say just how much the device would increase a healthy individual’s risk of cancer, but leaving a high-intensity model inside the body for weeks or months would result in a significant dose of radiation. The victim would likely notice the implant, though. They’re too big for an ordinary needle, and need to be inserted through a catheter.

You could, alternatively, contaminate the victim’s diet with high levels of aflatoxin, which is associated with liver cancer. Or you could infect her or him with any of a number of cancer-causing biological agents. Helicobacter pylori contributes to the development of gastric cancer, and human papillomaviruses can cause cervical, anal and a few other forms of cancer. But these tactics probably wouldn’t produce cancer in the short term and aren’t guaranteed to have any effect at all. In countries with high aflatoxin exposure, like China and parts of Africa, fewer than 1 in 1000 people develop liver cancer.


Most of the research on infusing cancer into humans is decades old. In the 1950s, Chester Southam gained notoriety by injecting hundreds of cancer patients and healthy prison inmates with live cancer cells. Southam wasn’t trying to give his subjects cancer. Rather, he was testing the efficiency with which the patients’ immune systems would reject the cells. He was so confident that the patients would fight off the invaders that he thought it unnecessary to tell them what he was doing. None of Southam’s patients seems to have developed metastatic cancer from his injections, and most modern oncologists believe the experiment posed little risk to the subjects. (One of the patients showed signs of a potentially spreading disease before dying of a separate illness.) Southam was sanctioned for fraudulent practices, however, and the case helped establish modern informed consent standards.

Southam’s experiments were abandoned in the 1950s, but he wasn’t the last doctor to inject a patient with live cancer cells. In 2009, a Taiwanese doctor was accused of implanting cancerous uterine cells into healthy patients as part of an insurance scam. While the insurance companies were out more than $660,000, none of the victims developed cancer.

Today, ethical physicians inject live cancer cells only into laboratory animals such as mice and rats. In most cases, the animals’ immune systems are compromised, or the rodents have been genetically engineered to rapidly spread mutant cells.