Scientists have warned lung cancer patients that nicotine could cause the disease to spread to the brain.
Smokers are far more likely to develop lung cancer than non-smokers.
Around 40 per cent of lung cancer patients also develop brain metastasis, but a new study has found this number is dramatically higher among smokers.
It is believed nicotine — which is found in cigarettes but is not in itself carcinogenic — is not only highly addictive but could be responsible for spreading the cancer.
A a result, scientists urge lung cancer patients who are habitual smokers to not only quit smoking, but instead go cold turkey and ditch nicotine altogether.
Once cancer spreads to the brain, the average life expectancy for patients is less than six months.
It is believed nicotine is not only highly addictive but could be responsible for spreading the cancer. A a result, scientists urge lung cancer patients who are habitual smokers to not only quit smoking, but instead go cold turkey and ditch nicotine patches (stock)
Analysis of 281 lung cancer patients in the US revealed a significantly higher incidence of brain cancer among cigarette smokers.
Researchers wondered what caused this relationship, so they analysed tumours from deceased patients and found large amounts of immune cells called M2 microglia.
These create and release chemicals which are capable of enhancing tumour growth.
In lab experiments on mice, the team from Wake Forest University then discovered that the nicotine encourages the formation of these microglia.
Removing the offending microglia from the brains of living mice prevented nicotine from inducing brain metastasis and enhanced the survival of mice with lung cancer.
US-based researchers found that nicotine promotes brain metastasis by stimulating the formation of immune cells called M2 microglia. Pictured, large numbers of M2 microglia (brown) in a metastatic brain tumour from a lung cancer patient who continued to smoke
Pod-based e-cigarettes like Juul make people more dependent on nicotine than other vapes
Electronic cigarettes that use flavoured pods are increasing dependency on nicotine, according to a new study.
The specific form of vaping has been dominated by US-based firm Juul and the easily-replaceable pods are extremely efficient at delivering a nicotine hit to users.
This type of e-cigarette is wildly popular with adolescents and young adults and the mixture of chemicals has been found to be more acidic than in other types of vape.
A new study found this acidity makes the fruity flavours more palatable, less harsh and therefore encourages deeper inhalation and increased nicotine absorbance.
Other manufacturers that use a similar pod-based system include Suorin, Bo, Phix, and Vuse Alto.
Pods are inserted into the main vape device and are intensely flavoured to resemble mango, mint and berries, for example.
Professor Kounosuke Watabe, lead author of the study, said: 'Many cancer patients find it difficult to quit smoking even after their diagnosis due to nicotine addiction.
'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.'
Professor Watabe and colleagues then looked for medicines that might reverse the effects of nicotine and identified parthenolide as a potential therapy.
The naturally occurring substance, which comes from the medicinal herb feverfew, blocked nicotine-induced brain metastasis in the mice.
Feverfew has been used for years to treat headaches and inflammation and is considered safe.
Professor Watabe believes parthenolide could provide a new approach to fight brain tumours, particularly for patients who are smokers or ex-smokers.
He said: 'Currently, the only treatment for this devastating illness is radiation therapy.
'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.'
Professor Watabe said he hopes to develop a clinical trial to test parthenolide in the near future, working with oncologists at Wake Forest School of Medicine, part of Wake Forest Baptist Health.