Smoking status must be captured in cancer trials: Experts

NT Correspondent

Bengaluru: A group of experts from AIIMS McMaster University in Canada and the International Agency for Re search on Cancer (IARC) in France has stressed the need to record smoking status in cancer clinical trials, warning that continued tobacco use can reduce treatment efficacy and patient survival.

In a commentary published in the Lancet Oncology this month, the seven authors, including Dr Abhishek Shankar from AIIMS Delhi, said knowl edge of smoking status during therapy could influence clinical decisions. They argued that ad dressing barriers to to bacco-use assessment and embedding smoking cessation initiatives into oncology research protocols will improve trial outcomes, enhance therapeutic efficacy and save lives.

The researchers cited the 2014 US Surgeon General's report 'The Health Consequences of Smoking -- 50 Years of Prog ress', which for the first time concluded there was a causal link between cigarette smoking and adverse cancer-related outcomes, including higher all-cause and cancer specific mortality.

This report underscores the need to systematically capture smoking status in clinical trials, to refine estimates of efficacy of novel therapies and to better understand the impact of continued tobacco use across treatment modalities and disease sites.

Since 2014, research has increasingly shown that continued tobacco use negatively impacts patients receiving surgery, radiotherapy or systemic therapies. The mechanisms by which tobacco smoke worsens outcomes remain unclear but may include tumour hypoxia, altered drug metabolism, stimulation of signalling pathways by nicotine and changes to the immune system, including re duced natural killer cells, the authors noted.

"Little is known about how best to overcome the effects of tobacco smoke, apart from cessation of tobacco use. Knowledge of smoking status during cancer therapy could po tentially influence clinical decisions," the authors said in the commentary. They cited how the dose of erlotinib has to be doubled (from 150 mg to 300 mg daily) to achieve ther apeutic concentrations in patients who continue smoking.

"These findings high light a large gap in our understanding of how continued tobacco use might influence drug metabolism, therapeutic response and long-term outcomes," the experts said, adding that the is sue is most pressing in low and middle-income countries with 80 per cent of tobacco users.

Meta-analyses of lung, head and neck, hormone-responsive and other cancers show that quitting smoking after diagnosis results in longer survival, with early quitting offering the great est benefits. The authors stressed that the survival advantage of quitting could even exceed the impact of the therapy under investigation.

They also cautioned that failure to collect smoking data risks confounding trial results, especially if treatment groups are unbalanced for tobacco use. The commentary pointed out that the 2020 US Surgeon General's report recommended structured cessation efforts as standard cancer care, though it said more data was needed to confirm a causal link with improved survival.