Ann Chao

The American Cancer Society Cancer Prevention Study II Nutrition Cohort: Rationale, Study design, and baseline characteristics

Large‐scale, prospective cohort studies have played a critical role in discovering factors that contribute to variability in cancer risk in human populations. Epidemiologists and volunteers at the American Cancer Society (ACS) were among the first to establish such cohorts, beginning in the early 1950s and continuing through the present, and these ACS cohorts have made landmark contributions in many areas of epidemiologic research.

The American Cancer Society Cancer Prevention Study II Nutrition Cohort

Large‐scale, prospective cohort studies have played a critical role in discovering factors that contribute to variability in cancer risk in human populations. Epidemiologists and volunteers at the American Cancer Society (ACS) were among the first to establish such cohorts, beginning in the early 1950s and continuing through the present, and these ACS cohorts have made landmark contributions in many areas of epidemiologic research.

Obesity, Recreational Physical Activity, and Risk of Pancreatic Cancer In a Large U.S. Cohort

Background: Obesity and physical activity, in part through their effects on insulin sensitivity, may be modifiable risk factors for pancreatic cancer. Methods: The authors analyzed data from the American Cancer Society Cancer Prevention Study II Nutrition Cohort to examine the association between measures of adiposity, recreational physical activity, and pancreatic cancer risk. Information on current weight and weight at age 18, location of weight gain, and recreational physical activity were obtained at baseline in 1992 via a self-administered questionnaire for 145,627 men and women who were cancer-free at enrollment. During the 7 years of follow-up, 242 incident pancreatic cancer cases were identified among these participants. Cox proportional hazards modeling was used to compute hazard rate ratios (RR) and to adjust for potential confounding factors including personal history of diabetes and smoking. Results: We observed an increased risk of pancreatic cancer among obese [body mass index (BMI) ≥ 30] men and women compared with men and women of normal BMI [<25; RR, 2.08; 95% confidence interval (95% CI), 1.48-2.93, Ptrend = 0.0001]. After adjustment for between BMI, risk of pancreatic cancer was independently increased among men and women who reported a tendency for central weight gain compared with men and women reporting a tendency for peripheral weight gain (RR, 1.45; 95% CI, 1.02-2.07). We observed no difference in pancreatic cancer incidence rates between men and women who were most active (>31.5 metabolic equivalent hours per week) at baseline compared with men and women who reported no recreational physical activity (RR, 1.20; 95% CI, 0.63-2.27). Conclusion: This study, along with several recent studies, supports the hypothesis that obesity and central adiposity are associated with pancreatic cancer risk.

Calcium, vitamin D, dairy products, and risk of colorectal cancer in the Cancer Prevention Study II Nutrition Cohort (United States)

Objective: Calcium, vitamin D, and dairy product intake may reduce the risk of colorectal cancer. We therefore examined the association between these factors and risk of colorectal cancer in a large prospective cohort of United States men and women. Methods: Participants in the Cancer Prevention Study II Nutrition Cohort completed a detailed questionnaire on diet, medical history, and lifestyle in 1992–93. After excluding participants with a history of cancer or incomplete dietary information, 60,866 men and 66,883 women remained for analysis. During follow-up through 31 August 1997 we documented 421 and 262 cases of incident colorectal cancers among men and women, respectively. Multivariate-adjusted rate ratios (RR) were calculated using Cox proportional hazards models. Results: Total calcium intake (from diet and supplements) was associated with marginally lower colorectal cancer risk in men and women (RR = 0.87, 95% CI 0.67–1.12, highest vs lowest quintiles, p trend = 0.02). The association was strongest for calcium from supplements (RR = 0.69, 95% CI 0.49–0.96 for ≥500 mg/day vs none). Total vitamin D intake (from diet and multivitamins) was also inversely associated with risk of colorectal cancer, particularly among men (RR = 0.71, 95% CI 0.51–0.98, p trend = 0.02). Dairy product intake was not related to overall risk. Conclusions: Our results support the hypothesis that calcium modestly reduces risk of colorectal cancer. Vitamin D was associated with reduced risk of colorectal cancer only in men.

A prospective study of whole grains, fruits, vegetables, and colon cancer risk:

Objective: We examined the relation between whole grains, fruit, vegetables and dietary fiber and colon cancer risk in the prospective Cancer Prevention Study II Nutrition Cohort. Methods: In 1992–1993, 62,609 men and 70,554 women completed questionnaires on medical history, diet and lifestyle behaviors. After exclusions, we confirmed 298 cases of incident colon cancer among men and 210 among women through August 31, 1997. Results: Multivariate rate ratios (RR) and 95% confidence intervals (CI) for all dietary factors were null. However, a statistically non-significant 30% reduction in risk was observed for men with the highest vegetable intakes (RR = 0.69, CI = 0.47–1.03, top versus. bottom quintile, p trend = 0.10). Men with very low (lowest tertile within the lowest quintile) intakes of vegetables and dietary fiber were at increased risk compared to those in the highest four quintiles of intake (vegetables RR = 1.79, CI = 1.22–2.61, p trend = 0.04, and fiber RR = 1.96, CI = 1.24–3.10, p trend = 0.006). Women with very low intakes of fruit were also at increased risk (RR = 1.86, CI =1.18–2.94, p trend = 0.06). Conclusions: Higher intakes of plant foods or fiber were not related to lower risk of colon cancer. However, our data suggest that very low intakes of plant foods may increase risk, and that certain phytochemical subgroups may decrease risk.

Cigarette smoking, use of other tobacco products and stomach cancer mortality in US adults: The Cancer Prevention Study II

Cigarette smoking is associated with increased risk of stomach cancer in many studies but there are limited data on this relationship in women and on risk associated with use of tobacco products other than cigarettes. We examined stomach cancer death rates in relation to cigarette smoking in women and use of cigarette, cigar, pipe, or smokeless tobacco in men in a nationwide prospective mortality study in the United States (US). Cohort follow‐up from 1982–96 identified 996 and 509 stomach cancer deaths among 467,788 men and 588,053 women, respectively. Cox proportional hazards models were fitted to estimate rate ratios (RR) and 95% confidence intervals (CI) using non‐users of tobacco as the referent group. Multivariate‐adjusted RRs were the highest for men who currently smoked cigars (RR = 2.29, 95% CI = 1.49–3.51) or cigarettes (RR = 2.16, 95% CI = 1.75–2.67) and both increased with smoking duration. Women who currently (RR = 1.49, 95% CI = 1.18–1.88) or formerly (RR = 1.36, 95% CI = 1.08–1.71) smoked cigarettes were at significantly increased risk, as were men who formerly smoked cigarettes (RR = 1.55, 95% CI = 1.28–1.88), or currently (RR = 1.81, 95% CI = 1.40–2.35) or formerly (RR: 1.57, 95% CI = 1.22–2.03) used more than one type of tobacco. Men who reported a history of chronic indigestion or gastroduodenal ulcer had substantially higher mortality rates associated with current cigarette (RR = 3.45, 95% CI = 2.05–5.80) or cigar (RR = 8.93, 95% CI = 4.02–19.90) smoking, as did men who were current aspirin users. If causal, the estimated proportion of stomach cancer deaths attributable to tobacco use would be 28% in US men and 14% in women. We conclude that prolonged use of tobacco products is associated with increased stomach cancer mortality in men and women. The accumulated evidence from this and other studies support reconsidering stomach cancer as a tobacco‐related cancer.

Meat consumption among black and white men and risk of prostate cancer in the cancer prevention study II nutrition cohort

Previous epidemiologic studies have suggested that intake of red meat may be associated with increased risk of prostate cancer. Few studies, however, have examined these associations by race. We examined intake of red meat, processed meat, and poultry in relation to incident prostate cancer among Black and White men in the Cancer Prevention Study II Nutrition Cohort. Participants in the study completed a detailed questionnaire on diet, medical history, and lifestyle in 1992 to 1993. After excluding men with a history of cancer and incomplete dietary information, 692 Black and 64,856 White men were included in the cohort. During follow-up through August 31, 2001, we documented 85 and 5,028 cases of incident prostate cancer among Black and White men, respectively. Cox proportional hazards models were used to estimate rate ratios (RR) and 95% confidence intervals (95% CI). No measure of meat consumption was associated with risk of prostate cancer among White men. Among Black men, total red meat intake (processed plus unprocessed red meat) was associated with higher risk of prostate cancer (RR, 2.0; 95% CI, 1.0-4.2 for highest versus lowest quartile; Ptrend = 0.05); this increase in risk was mainly due to risk associated with consumption of cooked processed meats (sausages, bacon, and hot dogs; RR, 2.7; 95% CI, 1.3-5.3 for highest versus lowest quartile; Ptrend = 0.008). This study suggests that high consumption of cooked processed meats may contribute to prostate cancer risk among Black men in the United States.(Cancer Epidemiol Biomarkers Prev 2006;15(2):211–6)

Underuse of Screening Sigmoidoscopy and Colonoscopy in a Large Cohort of US Adults

OBJECTIVES We examined the prevalence of endoscopy (sigmoidoscopy or colonoscopy) by indication and by demographic and lifestyle factors. METHODS We analyzed cross-sectional data collected in 1997 from participants aged 50 years and older in the Cancer Prevention Study (CPS) II Nutrition Cohort. RESULTS Fifty-eight percent of men and 51% of women reported ever having undergone endoscopy; only 42% of men and 31% of women reported endoscopy for screening rather than for disease diagnosis or follow-up. Prevalence varied by demographic and lifestyle factors. CONCLUSIONS Efforts to increase colorectal cancer screening need to target women, all persons aged 50-64 years, and those with colorectal cancer risk factors. Future studies should distinguish endoscopy for screening from procedures for disease diagnosis and follow-up to avoid overestimating screening compliance.

Multivitamin use and colon cancer mortality in the Cancer Prevention Study II cohort (United States)

Objective: Multivitamins contain several nutrients, including folic acid, which are hypothesized to reduce colon cancer risk. Previous epidemiologic studies have suggested that effects of multivitamins containing substantial amounts of folic acid (introduced in 1973) may not be evident until 15 or more years since first use. Methods: We examined the association between daily multivitamin use and colon cancer mortality among 806,397 US men and women in the Cancer Prevention Study II cohort who completed a questionnaire at enrollment in 1982 and were followed for mortality through 1998. Results: After multivariate adjustment, multivitamin use at enrollment showed little association with colon cancer mortality. After 15 years since first use of a multivitamin potentially containing folic acid, we observed slightly decreased risk of colon cancer mortality (rate ratio (RR) = 0.89, 95% confidence interval (CI) 0.80–0.99). Consistent with previous reports, this association was stronger among participants consuming two or more alcoholic drinks per day (RR = 0.71, 95% CI 0.56–0.91). Conclusion: Our results are consistent with a modest reduction in colon cancer mortality associated with use of folic acid-containing multivitamins among moderate to heavy alcohol users.

Smokeless tobacco use and the risk of Parkinson's disease mortality

We examined the association between smokeless tobacco use and Parkinsons disease (PD) mortality as assessed by death certificate in a prospective cohort of 95,981 never‐smoking men. In this cohort, smokeless tobacco use is inversely associated with PD mortality, with an age‐adjusted risk of 0.22 (0.07–0.67) among current users compared to never users.