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Smokers with higher C-reactive protein concentrations may have greater lung cancer risk

By Melanie Hinze
Current and former smokers with higher circulating high­-sensitivity C reactive protein (hsCRP) concentrations may have a greater risk of lung cancer, according to research published in the BMJ.

C-reactive protein (CRP), a biomarker of systemic inflamma­tion, has previously been shown to be associated with lung cancer risk. However, this study looked at the association specifically with respect to smoking status.

The nested case­-control study analysed circulating hsCRP concentrations in prediagnostic serum or plasma samples from 5299 patients with incident lung cancer and 5299 matched controls. Patients were sourced from the Lung Cancer Cohort Consortium, which included 20 population­-based cohort studies in Asia, Europe, Australia and the USA.

It found that current and former smokers with higher hsCRP concentrations had an increased risk for some histological subtypes of lung cancer, but not for adenocarcinoma. No association was found between higher hsCRP concentrations and lung cancer in people who had never smoked.

One of the study authors, Associate Professor Allison Hodge, from the Cancer Epidemiology and Intelligence Division, Cancer Council Victoria and the Centre for Epidemiology and Biostatistics at The University of Melbourne, said, ‘We included people who had never smoked, along with current and former smokers to further our understanding of the association between smoking, hsCRP and lung cancer risk’.

‘We hoped that if CRP added to the prediction of lung cancer risk, based on smoking, it could be used in addition to smoking and other risk factors to identify people for CT screening. However, as it happens we did not really see that it would be of benefit to find people at high risk for screening.’

What was seen was a substantial association between hsCRP concentration and risk of lung cancer in the first two years of follow up, particularly in current smokers.

‘Thus it seems likely that, rather than predicting that cancer will develop, the high hsCRP may be a marker of something already going on,’ Associate Professor Hodge told Medicine Today.

‘Despite this, it is always worthwhile for smokers to follow a healthier lifestyle, including giving up smoking, which has many benefits such as being anti­-inflammatory and possibly reducing CRP.’

‘In the Melbourne Collaborative Cohort Study alone, we found that healthier, less inflammatory diets were associated with a lower risk of developing cancer in smokers,’ she added.
BMJ 2018; 364: k4981.