Lung screening for non-smokers


IN Malaysia, lung cancer is one of the most prevalent cancers and a leading cause of cancer-related mortality among men.

As with all cancers, the survival or prognosis for lung cancer depends very much on the stage of the disease. Poor outcomes here are largely due to late-stage presentation and hence delayed diagnosis in almost 95% of cases.

Traditionally a male smokers’ disease, an emerging global trend in recent years is the alarming rise in cases among non-smokers, particularly women of East Asian ethnicity.

Findings of a landmark study from Taiwan (TALENT study) presented at the virtual congress of the World Conference on Lung Cancer (WCLC) in Singapore last month demonstrated the feasibility and value of screening high-risk non-smokers for early detection of lung cancer.

Before this, screening with a low dose computed tomography (LDCT) scan had been advocated only for heavy chronic smokers and former smokers largely based on two major international trials, the National Lung Screening Trial in the United States and the Dutch-Belgian Lung Cancer Screening trial (NELSON).

This latest Taiwanese study highlights the importance of genetics and correlated risk with a family history of the disease among first, second and third degree relatives. A significant family history was a highly relevant risk factor.

Smoking prevalence among Malaysian women remains low (2%) compared with men (about 45%), hence most female lung cancer victims here are non-smokers. Local data suggests that Malaysian Chinese females are almost twice as likely as Malay or Indian women to develop lung cancer even adjusting for age.

In comparison with the West, lung cancer victims here are slightly younger on average with a higher proportion of non-smokers. The cause of the disease in non-smoking Asian females, especially those of Oriental ethnicity, seems to have a strong genetic basis.

In today’s era of precision medicine, doctors and scientists can identify specific genomic molecular mutations within the cancer that may be amenable to bespoke targeted therapies. Such genetic anomalies, for example epidermal growth factor receptor (EGFR) mutation, are over-represented in lung cancers found in non-smoking East Asian women.

Given our relatively higher incidence of lung cancer in non- or never smokers compared with the West, it may be unwise to focus future screenings solely on those with a smoking history. LDCT screening may be a reasonable investigation for the high-risk non-smoker, for example a Chinese lady with a strong family history.

Other risk factors include a high cooking index (indoor wok cooking), exposure to passive smoking and previous tuberculosis. Paradoxically, as more cases of lung cancer are diagnosed in non-smokers, the nihilism and stigma associated with this curable disease will gradually wane.

Tomorrow is World Cancer Day.

DR HILMI LOCKMAN (Pulmonologist)

DR RAJA RIZAL AZMAN (Radiologist)

DR ANAND SACHITHANANDAN (Cardiothoracic surgeon) and DR THO LYE MUN (Clinical oncologist)

Members of Lung Cancer Network Malaysia

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Health; cancer screening

   

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