Quit Smoking? Here’s How Your Lung Cancer Risk Changes Over Time

Quitting Smoking Can Lower Lung Cancer Risk: Oncologist Explains What Changes Over Time

Smoking is one of the major risk factors for lung cancer and can have lasting effects on the respiratory system. However, stopping smoking begins to benefit the body relatively quickly, while the risk of developing lung cancer declines progressively over the years.

Dr Kumar Prabhash, Professor of Medical Oncology and Head of the Solid Tumour Unit at Tata Memorial Hospital and Director of Homi Bhabha Cancer Institute, Muzaffarpur, explained to HT Lifestyle how quitting smoking affects lung cancer risk and why former smokers may still need to remain vigilant.

Benefits begin soon after quitting

According to Dr Prabhash, the body starts recovering soon after a person stops smoking.

“Within about 12 hours of quitting, carbon monoxide levels in the blood can fall to normal,” he said.

Over the following weeks and months, lung function can improve, while symptoms such as coughing and breathlessness may decrease.

The reduction in cancer risk, however, takes considerably longer and continues over the years.

Dr Prabhash said that after 10 years without smoking, the risk of developing lung cancer can be around 30–60% lower than it would be for someone who continues to smoke.

Quitting smoking also lowers the risk of several other cancers. The benefits extend beyond the lungs, with smoking cessation associated with reduced risk of cancers including those of the liver, pancreas, bladder, kidney, stomach and colorectum.

Does the risk become the same as a never-smoker?

Stopping smoking substantially reduces the risk, but it does not necessarily bring it down to the level of someone who has never smoked.

“Quitting significantly lowers lung cancer risk, but former smokers continue to have a higher risk than never-smokers,” Dr Prabhash explained.

The extent of risk reduction differs between individuals and depends partly on their previous smoking exposure.

“Quitting does not reset the clock, but it does stop further exposure and gives the body an opportunity to recover,” he said.

This means that while quitting cannot completely erase the effects of years of smoking, it prevents continued exposure to harmful substances and gives the body a chance to repair some of the damage.

Former smokers may need to consider screening

Because former smokers can continue to face an elevated risk of lung cancer, people with a significant smoking history should discuss their individual risk with a healthcare professional.

Screening can help identify suspicious lung nodules at an earlier stage in people who meet appropriate criteria.

Dr Prabhash also pointed to advances in cancer diagnosis and treatment, including next-generation sequencing, which can provide more detailed information about the characteristics of a tumour.

Treatment options have also expanded.

“Treatment now involves many options, such as surgery, radiotherapy, chemotherapy, targeted therapy or immunotherapy, used alone or in combination depending on the type and stage of the cancer,” he said.

Access to care remains a challenge

While early detection and newer treatments have improved the management of lung cancer, access to specialised care remains uneven across India.

Patients living outside major cities can encounter delays at several stages, including diagnosis, specialist consultation and treatment. Dr Prabhash emphasised the need for stronger healthcare networks and collaboration to make comprehensive lung cancer care more accessible.

He also highlighted industry collaborations aimed at improving access to precision diagnostics.

According to him, initiatives such as the LuNGS Alliance can help address gaps in molecular testing and assist doctors in determining appropriate treatment options. The Cancer Research and Statistics Foundation has also developed an industry consortium involving organisations from healthcare, pharmaceutical and diagnostic sectors, including AstraZeneca, Pfizer, Roche and 4baseCare.

The broader message remains straightforward: quitting smoking is beneficial at any stage. While previous smoking exposure can leave a lasting impact on cancer risk, stopping prevents further exposure and allows the body to begin recovering.