Tobacco Smoking and Colorectal Cancer Risk: An Evaluation Based on a Systematic Review of Epidemiologic Evidence among the Japanese Population (original) (raw)
Related papers
Smoking and Colorectal Cancer in a Non-Western Population: a Prospective Cohort Study in Japan
Journal of Epidemiology, 2003
for the JACC Study Group. BACKGROUND: The risk of colorectal cancer in relation to smoking habits has been examined mostly in Caucasians, and evidence for other ethnic groups is still scarce. METHODS: Our data came from the Japan Collaborative Cohort (JACC) Study. From 1988 through 1990, 25,260 men and 34,619 women aged 40-79 years completed a questionnaire on cigarette smoking and other lifestyle factors. Hazard ratios (HR) were estimated by fitting proportional hazards models. RESULTS: During the mean follow-up of 7.6 years through December 1997, we documented 408 incident colon cancers and 204 rectal cancers. We found a non-significant increase in colon cancer risk in male current smokers compared with never smokers. The multivariate-adjusted hazard ratios were 1.07 (95% confidence interval [CI]: 0.72-1.59) for ex-smokers and 1.23 (95% Cl: 0.85-1.78) for current smokers. We however failed to observe a clear dose-response relationship between smoking intensity or duration and colon cancer risk. The adjusted hazard ratio was 1.07 (95% Cl: 0.71-1.61) even for 40+ years of smoking. Almost no increase in colon cancer risk was detected for female smokers, and male smokers were not at an enhanced risk of rectal cancer. CONCLUSIONS: Cigarette smoking was not a strong risk factor for colorectal cancer even after a long-term exposure, although a weak association remains open to discussion.
Japanese Journal of Clinical Oncology, 2006
Background: It is unclear whether tobacco smoking is related to colorectal cancer risk in Japan. We evaluated the association among the Japanese population based on a systematic review of epidemiologic evidence. Methods: Original data were obtained from searches of MEDLINE using PubMed, complemented with manual searches. The evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. Results: A total of six cohort studies and 15 case-control studies were thus identified. A substantial degree of heterogeneity was observed in the association between smoking and colon cancer; most case-control studies published before 1994 reported an inverse association, whereas studies conducted over the last decade did not find any significant association. Recent cohort studies have shown a non-significant 20-40% increase in colon cancer risk associated with current smoking. Several recent case-control studies and some cohort studies have identified a weak to strong positive association between smoking and rectal cancer. Conclusion: We conclude that tobacco smoking possibly increases the risk of colorectal cancer among the Japanese population. More specifically, tobacco smoking may possibly increase the risk of rectal cancer; however, epidemiologic evidence is still insufficient to demonstrate any clear association with colon cancer.
Smoking and colorectal cancer: A pooled analysis of 10 population‐based cohort studies in Japan
International Journal of Cancer, 2020
Smoking has been consistently associated with the risk of colorectal cancer (CRC) in Western populations; however, evidence is limited and inconsistent in Asian people. To assess the association of smoking status, smoking intensity and smoking cessation with colorectal risk in the Japanese population, we performed a pooled analysis of 10 population-based cohort studies. Study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox's proportional hazards model and then pooled using a random-effects model. Among 363 409 participants followed up for 2 666 004 person-years, 9232 incident CRCs were identified. In men, compared with never smokers, ever smokers showed higher risk of CRC. The HRs (95% CI) were
Japanese Journal of Clinical Oncology, 2005
Background: We evaluated the association between tobacco smoking and total cancer risk among Japanese populations based on a systematic review of epidemiological evidence. Methods: Original data were obtained from searches of MEDLINE using PubMed, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency for Research on Cancer. Meta-analysis of associations was also conducted to obtain summary estimates of association. Results: A total of eight cohort studies were identified. In men, all studies consistently showed a moderately increased risk of total cancer in current smokers compared with never-smokers. In women, an increase in risk was seen but was weaker than in men. The summary relative risk was estimated as 1.53 (95% confidence interval 1.41-1.65). Conclusion: We conclude that there is convincing evidence that current tobacco smoking moderately increases the risk (1.5 times) of total cancer in the Japanese population compared with never-smoking Japanese.
Smoking and Colorectal Cancer: A Meta-analysis
Jama-journal of The American Medical Association, 2008
Context Colorectal cancer is the third most common form of cancer and the fourth most frequent cause of cancer deaths worldwide. The association between cigarette smoking and colorectal cancer has been inconsistent among studies.
Cigarette Smoking and Colorectal Cancer Mortality in the Cancer Prevention Study II
2000
Background: Recent studies suggest that long-term cigarette smoking is associated with an increased risk of colorectal cancer. Whether the association is causal or due to confounding remains unclear. Methods: We examined cigarette smoking in relation to colorectal cancer mortality, evaluating smoking duration and recency and controlling for potential confounders in the Cancer Prevention Study II. This prospective nationwide mortality study of 1 184 657 adults (age ≥30 years) was begun by the American Cancer Society in 1982. After exclusions, our analytic cohort included 312 332 men and 469 019 women, among whom 4432 colon or rectal cancer deaths occurred between 1982 and 1996 among individuals who were cancer free in 1982. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated by fitting Cox proportional hazards models. All statistical tests were two-sided. Results: Multivariate-adjusted colorectal cancer mortality rates were highest among current smokers, were intermediate among former smokers, and were lowest in lifelong nonsmokers. The multivariate-adjusted RR (95% CI) for current compared with never smokers was ) among women. Increased risk was evident after 20 or more years of smoking for men and women combined as compared with never smokers. Risk among current and former smokers increased with duration of smoking and average number of cigarettes smoked per day; risk in former smokers decreased significantly with years since quitting. If the multivariate-adjusted RR estimates in this study do, in fact, reflect causality, then approximately 12% of colorectal cancer deaths among both men and women in the general U.S. population in 1997 were attributable to smoking. Conclusions: Long-term cigarette smoking is associated with increased risk of colorectal cancer mortality in both men and women. Clear reduction in risk is observed with early smoking cessation. [J Natl Cancer Inst 2000;92:1888-96]
Dietary patterns and colorectal cancer risk in Japan: the Ohsaki Cohort Study
Cancer Causes & Control, 2014
Purpose To evaluate dietary patterns in relation to colorectal cancer risk in Japanese. Methods We prospectively assessed the association between dietary patterns among the Japanese and the risk of colorectal cancer. Dietary information was collected from 44,097 Japanese men and women aged 40-79 years without a history of cancer at the baseline in 1994. Results During 11 years of follow-up, we documented 854 cases of colorectal cancer, which included 554 cases of colon cancer and 323 cases of rectal cancer. Factor analysis (principal component analysis) based on a validated food frequency questionnaire identified three dietary patterns: (1) a Japanese dietary pattern, (2) an ''animal food'' dietary pattern, and (3) a high-dairy, high-fruit-and-vegetable, lowalcohol (DFA) dietary pattern. After adjustment for potential confounders, the DFA pattern was inversely associated with the risk of colorectal cancer (hazard ratio of the highest quartile vs the lowest, 0.76; 95 % confidence interval 0.60-0.97; p for trend = 0.02). When colon and rectal cancers were separated, the inverse association between the DFA pattern and cancer risk was observed for rectal cancer (p for trend = 0.003), but not for colon cancer (p for trend = 0.43). No apparent association was observed for either the Japanese dietary pattern or the ''animal food'' dietary pattern. Conclusions The DFA dietary pattern was found to be inversely associated with the risk of colorectal cancer. This association was observed for rectal cancer, but not for colon cancer.
Cancer Epidemiology Biomarkers & Prevention, 2009
Background: Many studies have reported a 20% to 60% increase in risk of colorectal cancer associated with active smoking. However, neither the U.S. Surgeon General nor the IARC have classified the relationship as causal because of concern about residual confounding. Methods: In a prospective study of 184,187 people followed from 1992 to 2005, we used Cox proportional hazard models to examine the relationship of cigarette smoking to incident colorectal cancer, controlling for screening and multiple known and putative risk factors. Information on smoking and time-varying covariates was updated in 1997, 1999, 2001, and 2003. Results: The incidence of colorectal cancer was significantly higher in current [hazard ratios (HR), 1.27; 95% confidence intervals (CI), 1.06-1.52] and former smokers (HR, 1.23; 95% CI, 1.11-1.36) compared with lifelong nonsmokers in analyses that controlled for 13 covariates, including screening. The relative risk was greatest among current smokers with at least 50 years of smoking (HR, 1.38; 95% CI, 1.04-1.84). Among former smokers, risk of colorectal cancer decreased with greater time since cessation (P trend = 0.0003), and also decreased with earlier age at cessation (P trend = 0.0014). No association was seen among former smokers who had quit before age of 40 years or abstained for 31 years or more. Conclusions: Long-term cigarette smoking is associated with colorectal cancer, even after controlling for screening and multiple other risk factors. (Cancer Epidemiol Biomarkers Prev 2009;18(12):3362-7)
Cigarette Smoking and Colorectal Cancer: From Epidemiology to Bench
Journal of Experimental & Clinical Medicine, 2011
Colorectal cancer is the third most commonly diagnosed malignancy in the world. The risk factors include inherited genetic mutations and environmental elements such as a high-fat diet, low-fiber diet and sedentary lifestyle. Cigarette smoking is a serious worldwide health problem and the leading cause of preventable death. Although smoking increases the risk of cardiovascular disease and various cancers such as lung, oral and some gastrointestinal cancers, smoking is currently not recognized as a risk factor of colorectal cancer by either the International Agency for Research on Cancer (IARC) or the US Surgeon General. Accumulating epidemiological studies indicate that cigarette smoking is positively correlated to colorectal adenomatous polyps, and positive associations between cigarette smoking and colorectal cancer risk have been reported. Long-term cigarette smoking increases the risk of colorectal cancer mortality and the likelihood of a mutation occurring in the adenomatous polyposis coli (APC) tumor suppressor gene, which has a "gatekeeper" function in the colonic mucosa. Heavy smoking is associated with an increased risk of obtaining a mutation in BRAF, but not KRAS. Current and long-term smokers are at elevated risk of microsatellite instability high (MSI-H) colorectal cancers and an estimated one in five MSI-H colorectal cancers is attributable to cigarette smoking. Nicotine and its metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are two of the most causal elements for smoking-related cancers. Nicotine and NNK have been shown to induce colon cancer growth and even enhance the migration of colon cancer cells, which is a major cause of cancer death. In conclusion, cigarette smoking should be considered a risk factor of colorectal cancer.
Cancer …, 2009
BACKGROUNDThe majority of recent, well-designed studies have shown that long-term cigarette smoking increases colorectal cancer risk, but older studies with shorter durations of exposure often found no association. This study aimed to examine colorectal cancer risk by smoking exposure using data collected in the late 1950s and early 1960s.METHODSThis case-control study examined colorectal cancer risk by lifetime smoking history. There were 1,365 patients who visited Roswell Park Cancer Institute (RPCI) between 1957 and 1965 diagnosed with primary, incident colorectal cancers that were matched to 4,096 malignancy-free controls on gender and age. Odds ratios were calculated using separate logistic regression models for each smoking exposure, while controlling for other tobacco use, county of residence, race, age, gender, and body mass index (BMI).RESULTSThe adjusted OR for individuals who reported their greatest level of smoking to be more than 1 pack/day was 0.87 (95% CI=0.67–1.15). Among those who smoked 42 or more years, the adjusted OR was 0.89 (95% CI=0.68–1.15) compared to those who never smoked. For individuals who smoked more than 45 pack-years, the OR was 0.92 (95% CI=0.72–1.19). The results did not differ significantly by gender, although men had considerably greater exposure compared to women. Results also did not differ by colorectal sub-site.CONCLUSIONNo association was found between long-term cigarette smoking and colorectal cancer risk. These results are in accord with studies that followed cohorts throughout the 1950s and 1960s. Methodological limitations, such as missing data on covariates and the higher incidence of smoking-related illness in a hospital setting, may have contributed to the null results found in this study. Prolonged population exposure to cigarettes and perhaps a changing product may explain why more recent studies have reported a positive association between smoking and colorectal cancer.