World Lung Cancer Day: Doctor Explains Why Lung Cancer In Non-Smokers Is On The Rise

World Lung Cancer Day is observed globally on August 1 to raise awareness about lung cancer, its impact, and the importance of prevention, early detection, and treatment options. The day also aims to educate individuals about the risk factors for lung cancer, including smoking, air pollution and exposure to harmful substances. It also provides a platform to support those affected by lung cancer and emphasises on the urgent need to fight against this lung cancer.

According to the World Health Organisation, lung cancer is the leading cause of cancer-related deaths worldwide, with highest mortality rates among both men and women.

WHO has also identified smoking as the leading cause of lung cancer, responsible for approximately 85% of all cases.

Smoking not only affects the smoker but also those exposed to secondhand smoke, which can also contribute to the development of lung cancer in non-smokers. Other than secondhand smoke, many other environmental factors further exacerbate lung cancer risk in non-smokers.

Understanding lung cancer in non-smokers

"No cancer kills more than lung cancer. It is the most common cancer in men worldwide and is placed second when considering the number of new cancer cases in both sexes combined. It accounts for staggering 18% of all cancer deaths each year, while adding 11% to the new cancer burden during the same period. To put it straight, it's one of the cancers which have the poorest outcome," says Dr. Bhuvan Chugh, Principal Consultant - Medical Oncology, Max Hospital, Gurugram.

"The primary risk factor is smoking, which accounts for up to 90% cases of all lung cancers. Smoking increases the relative risk of lung cancer by 10-30-fold, and cessation brings it down by 20-90% and is evident within 5 years of cessation," he adds.

The expert further highlights that a rise in lung cancer cases has been observed in non-smokers over the past decade. "The reasons are a complex interplay between genetic and environmental factors. Environmental smoke exposure remains an important attributable risk in this population. Studies report that females have a 27 percent increased risk if partnered with an individual who smokes," Dr. Chugh states.

The second most important risk factor is air pollution; the International Agency for Research on Cancer (IARC) has classified outdoor pollution and particulate matter (PM) as a Group 1 human carcinogen for lung cancer. For each 10 micrograms of a substance per cubic meter of air increase in PM2.5 and PM10 concentration over the WHO-recommended air quality guidelines, there is an 8% & 9% increase in lung cancer incidence and deaths, respectively.

The difference between smokers' and non-smokers' lung cancer

"There are some vital differences in the lung cancer seen in smokers vs non-smokers. The lung cancer observed in non-smokers is significantly more likely to be driven by one gene, called a driver mutation, and hence is termed as onco-gene addicted lung cancer. This onco-gene addiction provides an opportunity to target the disease by an oral tablet or targeted therapy, both in early as well as advanced stages."

"This has led to improvement in tolerance to the treatment and overall survival. There are more than 10 genes identified that have been termed oncogenes for which targeted therapies are available. The majority of lung cancer patients who are diagnosed undergo genomic sequencing of their tumour for identification of these driver gene mutations before any treatment is given. This precise treatment of lung cancer, leading to improvement in survival, is a marvel of modern medicine," explains Dr. Chugh.

Smoking is a modifiable risk factor for lung cancer. Quitting smoking can greatly reduce the risk of lung cancer and many other serious health conditions.

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