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Time to first cigarette associated with risk for lung, head and neck cancer
Muscat JE. Cancer. 2011;doi:10.1002/cncr.26235.
Muscat JE. Cancer. 2011;doi:10.1002/cncr.26236.
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The earlier that smokers have their first cigarette after waking, the greater their risk for both lung cancer and head and neck cancer, results from two new studies show.
The results were published Aug. 8 online in the journal Cancer.
HemOnc Today Editorial Board member Michael B. Steinberg, MD, MPH, said the combined results show that not all smokers are alike, and smokers’ disease risk depends on genetic makeup.
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“An individual smoker’s risk for developing lung or head and neck cancer may be related to how dependent they are on nicotine,” Steinberg said in an interview. “Asking a question like ‘How soon do you smoke in the morning?’ may be a way of getting at that information and giving an individual their own risk for developing cancer.”
Both studies were conducted by Joshua E. Muscat, PhD, of the department of public health sciences at Penn State College of Medicine. In the first study, researchers said the time-to-first cigarette (TTFC) is a nicotine-dependent phenotype that predicts lung cancer after adjustment for smoking history.
Researchers segregated patients into three groups: Group A had their first cigarette more than an hour after waking (n=575); group B had their first cigarette 31 to 60 minutes after waking (n=722); and group C had their first cigarette within 30 minutes of waking (n=3,478).
The unadjusted OR for lung cancer was 1.78 (95% CI, 1.53-2.07) for group B and 3.56 (95% CI, 3.15-4.03) for group C compared with group A. In multivariate models controlled for socio-demographic characteristics, the pack-years adjusted OR for lung cancer was 1.31 (95% CI, 1.11-1.54) for group B and 1.79 (95% CI, 1.56-2.07) for group C compared with group A.
“There is clearly interindividual variability in the way smokers regulate their nicotine intake per cigarette, with increasing frequency in a natural setting and in attempting to quit,” the researchers concluded. “It is not feasible to measure how smokers regulate their nicotine uptake in studies of disease risk, but the TTFC is a behavior that is strongly associated with the level of cotinine per cigarette smoked. TTFC is a distinct nicotine dependence phenotype and was also shown to be an independent risk factor for lung cancer in the current study.”
In the second study, Muscat and colleagues conducted a case-control study evaluating the link between TTFC and the risk for head and neck cancer. With 1,055 patients and 795 controls, researchers again segregated the cohort into those who had their first cigarette more than an hour after waking (group A), first cigarette 31 to 60 minutes after waking (group B) and first cigarette within 30 minutes of waking (group C).
The crude OR for head and neck cancer associated with TTFC was 1.71 (95% CI, 1.26-2.34) for group B and 2.54 (95% CI, 1.98-3.25) for group C vs. group A. The pack-years adjusted OR for cancer was 1.42 (95% CI, 1.02-1.99) for group B and 1.59 (95% CI, 1.19-2.11) for group C. For group B, the OR was 1.43 (95% CI, 1.02-2.0) for total years of smoking-adjusted OR and 1.69 (95% CI, 1.45-1.98) for group C.
Except for cancers of the anterior and base of the tongue for patients in group B, early TTFC was associated with an increased risk for cancers of the mouth floor, palate and pharynx. Researchers found the strongest association between early TTFC and cancer of the pharynx in group C (OR=2.19; 95% CI, 0.99-4.83).
“Some people who smoke are more dependent than others. There seem to be genetic predispositions in the brain neurochemistry as to how we respond to nicotine,” Steinberg said. “How our brains respond to nicotine may determine how dependent we become. For those smokers who are highly dependent, and an indication of that is smoking soon after waking, those people are at the highest risk for developing cancers compared with those who can go an hour after waking.”
Steinberg said these findings provide further evidence that quitting smoking is not just a matter of willpower, but something that, in many cases, needs the attention of a medical professional.
“As time goes on, getting the message out that treatment for tobacco dependence is something you can and should seek help for. People don’t go through their doctor or even use over-the-counter nicotine replacement medicines because it’s tied into the perception that quitting smoking is just a bad habit that one chooses to do, rather than looking at tobacco dependence as a chronic medical condition. We need to change that perception. You wouldn’t try to treat diabetes or coronary artery disease on your own.” – by Jason Harris
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