Dietary determinants of one-carbon metabolism and the risk of non-Hodgkin's lymphoma: NCI-SEER case-control study, 1998-2000.

The role of dietary one-carbon determinants remains largely unexplored for non-Hodgkin's lymphoma (NHL). In a population-based case-control study of non-African-American adult (aged 20-74 years) women and men from four US Surveillance, Epidemiology, and End Results study centers (Detroit, Michigan; Iowa; Los Angeles, California; and Seattle, Washington; 1998-2000), the authors examined folate; vitamins B2, B6, and B12; methionine; and a one-carbon antagonist, alcohol, in 425 incident NHL cases and 359 controls who completed a detailed food frequency questionnaire. Adjusted odds ratios and 95% confidence intervals were estimated by using unconditional logistic regression. Higher intake of one-carbon determinants from food was associated with a lower risk of NHL, but that for only vitamin B6 (highest vs. lowest quartile: odds ratio = 0.57, 95% confidence interval: 0.34, 0.95; p trend = 0.01) and methionine (odds ratio = 0.49, 95% confidence interval: 0.31, 0.76; p trend = 0.002) reached statistical significance. Folate from food was inversely associated with diffuse subtype (odds ratio = 0.47, 95% confidence interval: 0.23, 0.94; p trend = 0.03). The authors found no association between total (food plus supplement) vitamins and NHL. Nonusers of alcohol had an elevated NHL risk compared with users, and alcohol did not modify other nutrient-NHL associations. Findings suggest that one-carbon nutrients, particularly vitamin B6 and methionine, may be protective against NHL.

Associations between bladder cancer risk factors and tumor stage and grade at diagnosis.

Using data on 1,860 bladder cancer cases and 3,934 population-based controls from the National Bladder Cancer Study, we examined associations between suspected bladder cancer risk factors and tumor stage and grade. Employment in a high-risk occupation was associated with the entire clinical spectrum of bladder cancer rather than a particular tumor stage or grade. For example, relative risks (RR) were similar for noninvasive and invasive disease (1.5 and 1.6, respectively). Cigarette smoking also increased risk of the entire clinical spectrum of bladder cancer, but the more advanced the stage, the stronger the effect. For example, relative risks of noninvasive and invasive bladder cancer for current heavy smokers were 3.0 and 5.2, respectively. Cigarette smoking was associated with higher risk of low-grade than high-grade tumors, once stage of disease was taken into account. Compared with whites, nonwhites were at a lower risk of noninvasive bladder cancer (RR = 0.4) but at similar risk of invasive bladder cancer (RR = 1.1), a pattern indicating racial differences in health practices related to bladder cancer detection. History of urinary tract infections and bladder stones was associated with increasing relative risks for advanced tumor stage. Heavy artificial sweetener use was associated with higher-grade, poorly differentiated tumors. Coffee consumption and family history of bladder cancer were not consistently associated with tumor stage or grade. Overall, different clinical presentations of bladder cancer share most suspected bladder cancer risk factors, including employment in a high-risk occupation and cigarette smoking.

Epidemiological characteristics of squamous cell carcinoma and adenocarcinoma of the bladder.

Recent incidence data from the United States indicate that transitional cell carcinoma accounts for the vast majority (95%) of bladder tumors in this country, with squamous cell carcinoma (less than 3%) and adenocarcinoma (less than 2%) comprising nearly all the remaining cases. Rates of squamous cell carcinoma and adenocarcinoma were higher in blacks compared to whites, while the reverse was true for transitional cell carcinoma. All three tumors predominated in males, especially transitional cell carcinoma. A population-based case-control study of bladder cancer conducted in 10 geographical areas of the United States identified 43 patients with squamous cell carcinoma and 32 with adenocarcinoma to permit an examination of risk factors. Cigarette smoking was significantly associated with risk of squamous cell carcinoma, with the relative risk rising to 6.1 among smokers of 40 or more cigarettes/day. Significantly elevated risks of squamous cell carcinoma were also associated with a history of 3 or more urinary tract infections (relative risk = 5.7) and with employment as welders and cooks. Risk factors were generally less conspicuous for adenocarcinoma, except for a significant trend with the amount of coffee drinking; however, this finding is based on small numbers and should be interpreted cautiously.

Familial and environmental interactions in bladder cancer risk.

In a population-based study of 2,982 bladder cancer patients and 5,782 controls in 10 geographic areas of the United States which was designed to assess the role of environmental risk factors, information was also obtained on the history of urinary tract cancer in first-degree relatives. A family history of urinary tract cancer significantly elevated the risk of bladder cancer [relative risk (RR) = 1.45], with higher risks observed among patients under age 45. The risks of bladder cancer associated with positive family history were generally higher among persons with suspected environmental exposures, particularly heavy cigarette smoking (RR = 10.7 among those who smoked 3 or more packs per day). Further studies of bladder cancer should incorporate biochemical and genetic probes to assess mechanisms of familial susceptibility and interactions with environmental factors.

Coffee drinking and risk of bladder cancer.

The relationship between coffee drinking and risk of bladder cancer was assessed with the use of data from a case-control study of bladder cancer. Incident cases (2,982) and general population controls (5,782) were interviewed. Overall, the relative risk (RR) of bladder cancer for subjects who had ever drunk coffee was estimated as 1.4 (95% confidence interval = 1.1-1.8). There was no consistent relation between the RR estimate and the current consumption level. Among men who drank coffee, those who drank more than 49 cupfuls of coffee per week had an apparent excess in risk, but women who drank that much had an apparent deficit in risk.

The prevalence of coffee drinking among hospitalized and population-based control groups.

Data on coffee-drinking habits obtained from a case-control study conducted in Detroit were used to compare the proportions of coffee drinkers in a hospital and a population control series. The comparison was based on interviews with 262 hospitalized controls and 427 population controls. The overall proportion of coffee drinkers in the total hospital control group was similar to that in the population control group. However, the proportion of moderate-to-heavy coffee drinkers among controls hospitalized for conditions that may have caused them to alter their diet (eg, gastrointestinal disorders and cardiovascular disease) was lower than that among population controls. In contrast, the proportion of moderate-to-heavy coffee drinkers among controls hospitalized for conditions that probably did not cause a change in diet (eg, fractures) was almost identical to that among population controls. These results suggest that, in hospital-based case-control studies of the effects of coffee consumption, it would be prudent to restrict the referent group to those patients hospitalized for conditions that probably did not cause a change in diet. The magnitude of bias resulting from failure to exclude controls hospitalized for diet-altering conditions will depend on two factors that may vary between studies: (1) the distribution of diet-altering conditions among the hospital controls, and (2) the relationship of these diseases to coffee consumption.