Abstrak: The effect of duration of cigarette smoking cessation on colorectal cancer risk by molecular subtypes remains unclear. Using duplication-method Cox proportional-hazards regression analyses, we examined associations between duration of smoking cessation and colorectal cancer risk according to status of CpG island methylator phenotype (CIMP), microsatellite instability, v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation, or DNA methyltransferase-3B (DNMT3B) expression. Follow-up of 134,204 individuals in 2 US nationwide prospective cohorts (Nurses' Health Study (1980-2008) and Health Professionals Follow-up Study (1986-2008)) resulted in 1,260 incident rectal and colon cancers with available molecular data. Compared with current smoking, 10-19, 20-39, and ≥40 years of smoking cessation were associated with a lower risk of CIMP-high colorectal cancer, with multivariate hazard ratios (95% confidence intervals) of 0.53 (0.29, 0.95), 0.52 (0.32, 0.85), and 0.50 (0.27, 0.94), respectively (Ptrend = 0.001), but not with the risk of CIMP-low/CIMP-negative cancer (Ptrend = 0.25) (Pheterogeneity = 0.02, between CIMP-high and CIMP-low/CIMP-negative cancer risks). Differential associations between smoking cessation and cancer risks by microsatellite instability (Pheterogeneity = 0.02), DNMT3B expression (Pheterogeneity = 0.03), and BRAF (Pheterogeneity = 0.10) status appeared to be driven by the associations of CIMP-high cancer with microsatellite instability-high, DNMT3B-positive, and BRAF-mutated cancers. These molecular pathological epidemiology data suggest a protective effect of smoking cessation on a DNA methylation-related carcinogenesis pathway leading to CIMP-high colorectal cancer.

Abstrak: Purpose: To identify factors predictive of smoking cessation among adults with chronic obstructive pulmonary disease (COPD). Data from the 1997 to 2002 National Health Interview Surveys were analyzed for adults at least 25 years of age with COPD using logistic regression.

Results: Of the adults with COPD, 36.2% were current smokers. Of the current smokers and former smokers who had quit smoking during the past year, 22.9% reported not receiving cessation advice from a health care professional during the past year Although half of smokers with COPD had attempted to quit during the past year, only 14.6% were successful. Attempting to quit was negatively associated with heavy drinking but positively associated with being younger and having cardiovascular diseases, lung cancer, and activity limitation due to lung problems. Factors predictive of successful cessation included being at least 65 years old, not being poor, and activity limitation due to lung problems.

Conclusion: This study underscores the importance of continuing to develop smoking cessation strategies for COPD patients and implementing clinical guidelines on smoking cessation among health care providers.