ABSTRACT
Many options are available to help with smoking cessation. Nonetheless, the success rates of smoking cessation programs are rather low, and half of all lung cancer cases occur in those who have stopped smoking. To help to reduce the incidence of lung cancer, recent efforts have been directed to chemoprevention. Chemoprevention is defined as the use of specific agents to reverse, suppress, or prevent the process of carcinogenesis. The rationale for chemoprevention is based on two main concepts, multistep carcinogenesis and ‘field cancerization ’ , which can be used to explain the process of lung carcinogenesis as it occurs over time and throughout the entire bronchoalveolar epithelium. Although chemoprevention as a means of reducing cancer incidence has been successful for breast and prostate cancer, it is a developing area of research for lung cancer. The main goal for lung cancer chemoprevention is to find a compound with a favorable toxicity profile for patients who are at high risk for primary or secondary lung cancer. A number of compounds have been tested, but results of trials to date have been negative or, in the case of beta-carotene and retinoids, even detrimental. A comprehensive overview of past and ongoing chemoprevention trials can be found in the paper by Omenn. 1 Based on these data, the American College of Chest Physicians (ACCP) formulated guidelines which are summarized in Table 4.1 . 2
Several recent papers deserve special attention. The first is on the effect of the inhalation of corticosteroids on lung cancer incidence. 3 Compared with control subjects, those receiving high-dose inhaled corticosteroids ( > 1200 µ g of triamcinolone equivalents, n = 219) had a decreased risk for lung cancer (hazard ratio 0.39, 95 % confidence interval (CI) 0.16 – 0.96). The weaknesses of this study are the relatively small number of subjects and incident cases of lung cancer and the fact that the diagnosis of chronic obstructive pulmonary disease (COPD) and the histopathology of lung cancer were not confirmed. 4 Recently, a metaanalysis of seven randomized trials on the effect of inhaled steroids on all-cause mortality in COPD patients was published. 5 None of the mortality causes were significantly reduced, but lung cancer mortality showed a trend toward a decreased risk (hazard ratio 0.47, 95 % CI 0.22 – 1.00). Although the available data are not definitive and need further investigation, inhaled corticosteroids
deserve further consideration for lung cancer chemoprevention. van den Berg et al investigated the effect of 500 µ g fluticasone on the number of pulmonary nodules detected on a single slice computed tomography (CT) scan of the chest. 6 Compared with a placebo control group ( n = 54), more nodules resolved in the fluticasone arm and fewer subjects had new nodules, although these trends did not reach significance.
