Screening non-smokers for lung cancer just as important & effective, finds Taiwan study

Study by National Taiwan University College of Medicine which screened never-smokers based on family history, other risk factors identified a high baseline prevalence of lung cancer.

Representational image | Commons

Nagpur: Lung cancer in ‘never-smokers’ or people who have never smoked is a rising threat, and a new study from Taiwan has emphasised the importance of screening among certain risk groups to identify the disease early. 

According to researchers from the National Taiwan University College of Medicine, Taipei, low-dose computed tomography (LDCT) screening — currently the only recommended test for lung cancer screening — may be “feasible” in never-smokers exposed to certain risk factors, such as a family history of lung cancer and exposure to second-hand smoke. 

The findings of the team, which was led by Dr Pan Chyr Yang of the National Taiwan University College of Medicine, were presented at the International Association for the Study of Lung Cancer (IASLC) 2020 World Conference on Lung Cancer (WCLC) in Singapore this January.

For their study, the researchers developed the Taiwan Lung Cancer Screening for Never-Smoker Trial (TALENT), a nationwide study for which more than 12,000 individuals aged 55 to 70 years were enrolled. 

The participants were never-smokers as well as those who hadn’t smoked in more than 15 years. All had at least one among a group of risk factors — family history of the disease, passive smoke exposure or regular exposure to fumes from frying food. Of the 12,011 individuals enrolled in the trial, lung cancer was detected in 313 participants (2.6 per cent). 

“The study revealed that LDCT screening for lung cancer in never-smokers with high risk may be feasible, which is very important to all who are fighting against lung cancer, (considering) the increasing global threat for lung cancer in never-smoker. Most importantly, the study showed that family history of lung cancer may increase the risk of lung cancer,” principal investigator Pan Chyr Yang said in a statement presented alongside the study.

The study comes as a growing number of non- or light smokers are diagnosed with lung cancer. According to a 2018 study by researchers from China, this percentage is believed to be substantially higher in East Asian countries, where approximately one-third of all lung cancer patients are reportedly never-smokers. 

Researchers not involved with the Taiwanese study described it as a welcome initiative, flagging the absence of any recommended lung cancer screening framework for non-smokers. 

Some patients battling lung cancer also want people to reject the commonly held belief that smoking alone leads to the disease, which is one of the top 10 causes of death around the world. This narrative, they say, can be dangerous.

Smoking not the only cause of lung cancer

An estimated 72,510 new lung cancer cases were diagnosed in India last year, with the disease resulting in 66,279 deaths, according to the GLOBOCAN report 2020. GLOBOCAN is a WHO-affiliated web-based platform for cancer statistics.

Many studies conducted in recent years have pointed out that non-smokers could also be at high risk of being diagnosed with lung cancer. 

A 2018 study by Delhi’s Sir Ganga Ram Hospital (SGRH) showed that the number of non-smokers with lung cancer in north India was the same as that of smokers. Of the 150 lung cancer cases studied between March 2012 and June 2018 for the study, 50 per cent were found to be non-smokers. 

This is in line with the findings of a 2012 study carried out by researchers at Mumbai’s Tata Memorial Hospital. According to the study, 52.1 per cent of lung cancer patients had no history of smoking. Indoor air pollutants such as cooking oil fumes and coal-stove smoke, it added, could be contributing factors among patients from rural India.

Large randomised studies like the 2013 National Lung Screening Trial (NLST) and the 2020 NELSON trial have previously demonstrated that the use of low-dose CT is effective for lung cancer screening. These results have led to recommendations on appropriate lung cancer screening for a certain group of high-risk individuals — mainly patients who are active smokers or have a substantial smoking history.

However, no guidelines for screening exist for non-smokers and light-smokers.

“Currently, there is no recommended screening for patients not meeting such criteria, and there is certainly a great need for further data to address the appropriateness and impact of screening in non-smokers — especially in populations where the incidence seems particularly high, such as in East Asia,” said Dr Balazs Halmos, professor of Medicine and chief of Thoracic Oncology at Montefiore Medical Center, Albert Einstein College of Medicine, US. 

“For this reason, the results of the TALENT study are very welcome. This study looked at a large enriched non-smoking patient cohort from Taiwan based on family history and other lesser risk factors and identified a strikingly high baseline prevalence of lung cancers — 2.6 per cent, higher than what was noted in the NLST and NELSON studies,” he added.

Dr Vanita Noronha, a thoracic oncologist at Tata Memorial Hospital, said the results of the TALENT study are very promising for the Indian population. 

“The prevalence of lung cancer in never-smokers in India is very high, about 53 per cent. Although these numbers might seem surprising, similar results have been obtained in other Asian countries like Taiwan and Singapore,” she added.

It is a common notion that if you have never puffed on a cigarette in your life, you won’t get lung cancer. But Jill Feldman, a US-based lung cancer patient and awareness advocate, believes “the single story that only people with a smoking history can get lung cancer is dangerous”.

“The stigma has created barriers to diagnosis and treatment, but also to critical research into the other risk factors associated with lung cancer, which leaves people with a false sense of security that if they have never smoked, then they won’t get lung cancer,” she said.

Feldman has presented patient perspectives internationally at the World Conference on Lung Cancer, hosted by the International Association for the Study of Lung Cancer (IASLC), an international network dedicated to the study and elimination of lung cancer. She continues to work with the organisation as a member of its patient advisory board. 

Asked about the TALENT study, she said, “I think the TALENT study is significant and something that warrants further studies globally. The fact that if cigarettes never existed, lung cancer would still be one of the top 10 cancer diagnoses each year is reason enough!”

Chinmay Haridas is a medical student and works with the American Lung Cancer Screening Initiative (ALCSI), a US-based non-profit