Cigarette Smoking and Cancer Risk: Modeling Total Exposure and Intensity

Abstract

A recent analysis showed that the excess odds ratio (EOR) for lung cancer due to smoking can be modeled by a function which is linear in total pack-years and exponential in the logarithm of smoking intensity and its square. Below 15-20 cigarettes per day, the EOR/pack-year increased with intensity (direct exposure rate or enhanced potency effect), suggesting greater risk for a total exposure delivered at higher intensity (for a shorter duration) than for an equivalent exposure delivered at lower intensity. Above 20 cigarettes per day, the EOR/pack-year decreased with increasing intensity (inverse exposure rate or reduced potency effect), suggesting greater risk for a total exposure delivered at lower intensity (for a longer duration) than for an equivalent exposure delivered at higher intensity. The authors applied this model to data from 10 case-control studies of cancer, including cancers of the lung, bladder, oral cavity, pancreas, and esophagus. At lower intensities, there was enhanced potency for several cancer sites, but narrow ranges for pack-years increased uncertainty, precluding definitive conclusions. At higher intensities, there was a consistent reduced potency effect across studies. The intensity effects were statistically homogeneous, indicating that after accounting for risk from total pack-years, intensity patterns were comparable across the diverse cancer sites.

Identifying patients with suspected lung cancer in primary care: derivation and validation of an algorithm

“…Evidence suggests that age, deprivation, previous diagnoses of other cancers, previous pneumonia, family history of lung cancer, and asbestos exposure also increase long-term risk independently of smoking. 8,11 In addition, 'red-flag' symptoms such as haemoptysis, loss of appetite, dyspnoea, and cough might herald an existing condition of lung cancer, 12 especially among individuals with a high baseline risk. However, an approach that focuses on individual 'red-flag' symptoms such as haemoptysis without taking account of other risk factors is likely to miss 80% of current lung cancers.…”

“…• 11,14,15,22 • chronic obstructive airways disease diagnosed ever (yes/no); 8,14 • Townsend deprivation score (continuous); 23 • family history of lung cancer (yes/no); 8,14 …”

Association Between C-reactive Protein and Risk of Cancer: A Meta-analysis of Prospective Cohort Studies

“…Because gender, obesity and smoking may be influential factors for cancer risk (Bianchini et al, 2002;Lubin et al, 2007), it is plausible to think that differences in gender composition and adjusted variables of BMI and smoking might be possible sources of heterogeneity. Unexpectedly, no supportive results were found from meta-regression analyses.…”

Effects of Radiation and Lifestyle Factors on Risks of Urothelial Carcinoma in the Life Span Study of Atomic Bomb Survivors

“…Lubin (45) and Baris (55) found increased excess odds ratios per pack-year of smoking at lower levels of smoking intensity. We found no statistical evidence that smoking intensity modified pack-years of smoking risk estimates.…”

“…Sub-analyses included calculations of radiation and smoking attributable fractions using an additive ERR model. Another sub-analysis modeled packyears of smoking as an additive ERR term to model total smoking exposure as suggested by Lubin et al (45).…”