Scientists uncover link between air pollution and lung cancer

What did the researchers find?

The findings, based on research led by the Francis Crick Institute in London and funded by Cancer Research UK, were released at the European Society for Medical Oncology Congress in Paris on Saturday.

X-ray of a lung cancer patient. (Creative Commons)

They found that the cells with Epidermal Growth Factor Receptor (EGFR) and KRAS gene mutation can turn cancerous when exposed to air pollutants like car fumes, which “awaken” dormant mutations in lung cells and move them into a cancerous state. 

“The risk of lung cancer from air pollution is lower than from smoking, but we have no control over what we all breathe,” said Prof Charles Swanton of the Francis Crick Institute, who presented the findings at the European Society for Medical Oncology conference in Paris on Saturday, 10 September.

What does EGFR mutation mean?

Explaining the EGFR gene mutation, which is very common in lung cancer patients of nonsmokers in India, Dr Nitin Yashas, a consultant on medical oncology at the Sarjapur and Jayanagar campuses of the Manipal Hospital in Bengaluru, who is not associated with the study, told South First that EGFR was a protein found on the surface of body cells.

He said each and every function of the cell, which is the basic structure of the human body, is governed by the DNA, which can be assumed to be the software of our body.

“The DNA contains the message for every cell to perform its functions and regulate it. Now, just like a software bug, an error in the DNA — this is called a mutation — can occur due to a variety of factors, including just the normal process of ageing. Some of these mutations such as EGFR and KRAS generate signals for the cells to continually divide. When cells, which already have these mutations as part of the ageing process, are exposed to carcinogens like those causing air pollution, these become cancerous,” Yashas explained.

He added that a majority of nonsmokers getting lung cancer in India have this mutation.

It has been known for many years that nonsmokers always carry a mutation.

“In clinical practice, when we see patients who are nonsmokers diagnosed with lung cancers, we send the tumour tissue to test for the mutation. This EGFR mutation is the most common one in them,” said Yashas.

He explained that the finding of the EGFR mutation paved the way for targeted therapy instead of chemotherapy in lung-cancer patients.

“There are tablets and other medicines to help in target-based therapy. But several patients come to us only during their fourth stage,” he said. 

How will this research help us?

The study shows the importance of addressing climate health in the improvement of human health, said the researchers from London.

This holds good globally, with about 300,000 lung-cancer deaths in 2019 attributed to the exposure to fine particulate matter — PM2.5 — contained in air pollution. Yashash said every other lung-cancer patient in India is a nonsmoker. 

“Doctors used to make blanket statements to every patient when they would ask: ‘Why me? I don’t smoke or drink, and I exercise!’ We would say it was multifactorial and air pollution was also one of the reasons causing lung cancer,” said Yashas. 

“The researchers for the first time found that the two mutations — in the EGFR and KRAS genes — commonly found in lung cancers are actually present in any normal lung tissue. And when they exposed these cells carrying dormant mutations to PM2.5 particles, they turned cancerous. And also, they occurred quicker than when lung cells with these mutations were not exposed to pollutants,” he added.

Meanwhile, Dr Ravi Thippeswamy, a consultant medical, hemat, and paediatric oncologist at the Sri Shankara Cancer Hospital in Bengaluru, said, “We need to wait for more analysis and research in this area. Though we knew that there was a link between pollution and lung cancer for a long time, we now have an explanation for this. It is like a wake-up call to look into climate change and pollution.”