The level of nicotine dependence is an independent risk factor for cancer: a case control study

Less than 20% of lifetime smokers will ever develop cancer. Smoking habits characteristics, particularly the level of nicotine dependence level, were not fully evaluated as a marker of risk.

Case-control study of voluntary patients prospectively enrolled in a smoking cessation program in a cancer hospital. For each cancer case, patients of the same age and sex were selected. The Beck Depression Inventory, an instrument for the diagnosis of depressive mood and clinical depression, and the Fagerström Test Questionnaire, a questionnaire that has a good correlation with nicotine levels, used to determine the degree of dependence on nicotine, were applied. Age on admission to the study, sex, and number of pack-years were also evaluated.

From May 1999 to May 2002, 56 cancer patients (case) and 85 matching controls (control) were identified in the population studied. There was no difference regarding pack-years. Fagerström Test Questionnaire was significantly higher in patients with cancer (7.5+/-1.9) compared to controls (6.3+/-2.0). We found a Fagerström Test Questionnaire>7 in 73.2% of the cancer cases versus 43.5% of the controls (p=0.001). The proportion of depressed patients was higher in the cancer group (37.5% x 17.6%). Logistic regression adjusted for age and tobacco consumption disclosed that Fagerström Test Questionnaire score>7 has an odds ratio for cancer of 3.45 (95% CI 1.52-7.83, p=0.003).

Fagerström Test Questionnaire higher than 7 was identified as a risk factor for cancer in smokers with similar tobacco consumption.