Nuclear morphometry as a biomarker for bronchial intraepithelial neoplasia: correlation with genetic damage and cancer development.

BACKGROUND: Bronchial carcinomas are preceded by epithelial morphologic changes. The variation in interpretation of these grades of intraepithelial neoplasia makes it difficult to determine its natural history and utility of histopathology as a surrogate endpoint biomarker. The objective of this study was to quantitate morphologic changes of intraepitherlial neoplasia and validate its utility through correlation with histopathology, allelic loss, and cancer development. METHODS: Quantitative nuclear morphometry was performed on 47 normal bronchial biopsies and 28 invasive cancer to generate a morphometry index (MI) that was applied to 1,096 bronchial biopsies from 230 volunteers who were current smokers (> or =25 pack-years) and 30 patients who had cancer. In a subset of 631 biopsies, MI was correlated with frequency of loss of heterozygosity at nine chromosomal regions (14 polymorphic markers). RESULTS: A significant correlation was found between MI and allelic loss in six of nine chromosomal regions. As part of patient long-term follow-up, 12 sites that progressed to cancer were identified and had significantly increased MIs relative to nonprogressing sites. Significant overlap in the MIs was found between most grades of intraepithelial neoplasia. CONCLUSIONS: In chemoprevention trials, nuclear morphometry can supplement histopathology as a Surrogate Endpont Biomarker (SEB) because it is quantitative, collelates well with genetic damage, and may predict cancer development.

Surrogate end-point biomarker analysis in a retinol chemoprevention trial in current and former smokers with bronchial dysplasia.

Epidemiological studies suggested that vitamin A may be protective against lung cancer, however, recent chemoprevention trials with beta-carotene, a precursor of vitamin A, demonstrated enhancement of lung carcinogenesis among smokers. Whether vitamin A is beneficial or harmful in chemoprevention of lung cancer in smokers has not been resolved. This study was designed to determine the effect of retinol alone in current and former smokers using bronchial dysplasia, nuclear morphometry and retinoic acid receptor-beta (RAR-beta) mRNA expression as surrogate end-point biomarkers (SEBs). Eighty-one current or former smokers with a smoking history of >/=30 pack-years were randomized to receive either placebo or retinol (50,000 IU per day) for six months. Fluorescence bronchoscopy was performed prior to treatment to localize areas suggestive of dysplasia. At least 4 bronchial biopsies were taken per subject including at least two biopsies from apparently normal areas. The same areas were precisely re-biopsied after 6 months. Any new areas suggestive of dysplasia were also biopsied. Changes in the SEBs were assessed before and after treatment. At baseline, the frequency of biopsies negative for RAR-beta expression was: normal (23%), hyperplasia (28%), metaplasia (41%), mild dysplasia (41%), and moderate/severe dysplasia (44%). There was no significant difference in the regression rate between the retinol and placebo groups using histopathology and nuclear morphometry as SEBs. The likelihood of regression was found to be lower in those who continued to smoke during the study (OR=1.86 for those smoking >10 cigarettes per day, p=0.084 to OR=0.95, p=0.26 for those smoking 20+ per day compared to ex-smokers). Retinol was not effective in the up-regulation of RAR-beta in lesions with bronchial dysplasia. We postulate that the lack of effect of retinol on RAR-beta expression among individuals who continued to smoke while taking retinol may be due to suppressive effect of tobacco smoke constituents on RAR-beta expression and/or altered cellular metabolism of retinol to retinoic acid and its isomers.

A randomized phase IIb trial of anethole dithiolethione in smokers with bronchial dysplasia.

BACKGROUND: Results from preclinical studies have suggested that the organosulfur compound anethole dithiolethione (ADT) may be an effective chemopreventive agent for lung cancer. We conducted a phase IIb study to determine the effects of ADT in smokers with bronchial dysplasia. METHODS: One hundred twelve current and former smokers with a smoking history of at least 30 pack-years and at least one site of bronchial dysplasia identified by an autofluorescence bronchoscopy-directed biopsy were randomly assigned to receive placebo or ADT at 25 mg orally thrice daily for 6 months. Each subject then underwent a follow-up bronchoscopy-directed biopsy. We used changes in histopathologic grade and nuclear morphometry index (MI) as the primary and secondary end point biomarkers, respectively. Chi-square tests with continuity correction were used to compare response rates on a lesion- and person-specific basis between the two study groups. All statistical tests were two-sided. RESULTS: One hundred one subjects had a follow-up bronchoscopy. In the lesion-specific analysis, progression rate of pre-existing dysplastic lesions by two or more grades and/or the appearance of new lesions was statistically significantly lower in the ADT group (8%) than in the placebo group (17%) (P<.001; difference = 9%, 95% confidence interval [CI] = 4% to 15%). In the person-specific analysis, the disease progression rate was statistically significantly lower in the ADT group (32%) than in the placebo group (59%) (P =.013; difference = 27%, 95% CI = 6% to 48%). The two treatment groups did not differ statistically significantly in terms of nuclear MI. Among individuals with an abnormal nuclear MI before treatment (29 in the ADT group and 25 in the placebo group), the progression rate in the ADT group (41%) was substantially lower than that in the placebo group (60%), although the difference was not statistically significant (P =.28; difference = 19%, 95% CI = -11% to 49%). Adverse events were mostly minor gastrointestinal symptoms that resolved with dose reduction or discontinuation of the medication. CONCLUSION: Our results suggest that, in smokers, ADT is a potentially efficacious chemoprevention agent for lung cancer.