Nicotine patches and gum meant to help quit smoking may promote brain tumors in lung cancer patients: Study
Nicotine patches, gum and other replacement options that help lung cancer patients quit smoking can induce brain tumors, claims a new study. Experts suggest that these patients should consider steering clear of these withdrawal products. The study could also explain why many lung cancer patients with smoking history develop lumps in the brain. Up to 40% develop metastatic brain tumors and they often do not survive beyond six months.
"Many cancer patients find it difficult to quit smoking even after their diagnosis due to nicotine addiction," says Dr Kounosuke Watabe, professor of cancer biology at Wake Forest School of Medicine and lead author of the study. "E-cigarette, nicotine patch and nicotine gum are commonly used as nicotine replacement therapies to help these patients cease smoking. However, our results clearly show that nicotine has profound and long-term effects on brain metastasis progression, suggesting that cancer patients should be cautious in their use of nicotine for smoking cessation," he adds.
Understanding how nicotine induces brain tumor has another advantage: discovering new drugs. "Currently, the only treatment for this devastating illness is radiation therapy," Watabe explains. In this study, Watabe's team studied 281 lung cancer patients. Analyzing their data showed a pattern — brain tumor commonly struck smokers than their non-smoker counterparts or those who gave it up. These findings establish a link but do not explain why these patients develop brain metastasis. So Watabe and his team set out to explore more.
They enlisted mice in their study to understand whether nicotine had something to do with the lung cells spreading to the brain. They observed that the nicotine traveled to the brain and transformed a cell involved in immunity: microglia. So instead of being protective, the scientists claim, these cells turned destructive. In other words, the altered microglia began enhancing tumor growth.
However, when they removed the transformed brain cell from the brains of the mice, they found that nicotine could no longer promote tumor in the brain. What is more, the mice survived the assault. Watabe and colleagues then looked for drugs that might reverse the effects of nicotine and a compound named parthenolide appeared to fit the bill. It is present at high levels in the medicinal herb Feverfew, which has been used for centuries to treat headaches and inflammation. Because the drug is known to be safe, Watabe believes it may provide a new approach to fight brain metastasis, particularly for patients who have smoked or still smoke.
Testing the drug on mice showed that it rescued rats, helping them survive. It works by preventing nicotine from transforming the microglia, thereby blocking the spread of lung cancer cells to the brain, researchers explain. "Traditional chemotherapy drugs can't cross the blood-brain barrier, but parthenolide can, and thus holds promise as a treatment or possibly even a way to prevent brain metastasis," he adds.
"We, therefore, think that parthenolide could be useful for the prevention and treatment of brain metastasis, particularly for patients with past and current smoking history," Watabe says. The study appears in the June 4 edition of the Journal of Experimental Medicine.