Calcium, vitamin D, and dairy product intake and prostate cancer risk: the Multiethnic Cohort Study.

High intakes of calcium and dairy products have been suggested to be related to prostate cancer risk. Such associations were examined in the Multiethnic Cohort Study (1993-2002) among 82,483 men who completed a detailed quantitative food frequency questionnaire. During a mean follow-up of 8 years, 4,404 total cases of prostate cancer were identified. In Cox proportional hazards models, no association was found between calcium and vitamin D intake and total, advanced, or high-grade prostate cancer risk, whether for total intake, intake from foods, or intake from supplements, among all male participants or among nonusers of supplemental calcium. No association of calcium or vitamin D intake was seen across racial/ethnic groups. In analyses of food groups, dairy product and total milk consumption were not associated with prostate cancer risk. However, low-/nonfat milk was related to an increased risk and whole milk to a decreased risk of total prostate cancer; after stratification, these effects were limited to localized or low-grade tumors. Although the findings from this study do not support an association between the intakes of calcium and vitamin D and prostate cancer risk, they do suggest that an association with milk consumption may vary by fat content, particularly for early forms of this cancer.

Prostate cancer incidence and intake of fruits, vegetables and related micronutrients: the multiethnic cohort study* (United States).

OBJECTIVE: To describe the relationship between the intake of fruits, vegetables, and related vitamins and antioxidants, and the risk of prostate cancer in male participants in a large multiethnic cohort study. METHODS: Food and nutrient intakes in 1993-1996 were calculated from a detailed food frequency questionnaire (FFQ) designed to account for the food and nutrient intake of the ethnic groups represented in the study (82,486 African-American, Japanese-American, Native-Hawaiian, Latino and White males included here). Follow-up for incident cancers utilized local SEER registries. Vital status was ascertained using state death files. Data on PSA utilization from a later questionnaire was also examined. RESULTS: A total of 3,922 incident cancer cases were ascertained during follow-up. Modestly increased risks of prostate cancer were observed in relation to higher intakes of several food items including light green lettuce and dark leafy green vegetables. Notably, no significant protective associations of any foods were seen, including tomato intake; and intakes of two complex foods containing tomato sauce (pizza and Spanish rice) were associated with modest increases in risk. PSA test use was significantly and positively related to intake of some of these same items, implying a degree of disease detection-bias. Analysis of non-localized and high grade disease (1,345 cases) showed no significant protective associations with overall fruits and vegetables intake, related micronutrients, or with intake of selected complex food items. CONCLUSIONS: We found no statistically significant evidence of a protective effect against prostate cancer of higher levels of intake of any of these foods, associated micronutrients or supplements. A possible explanation for the positive associations with risk of several of the foods normally considered to be healthy is detection bias, since "healthy" dietary intake was related to greater use of the PSA test.

Impact of radiotherapy for high-risk neuroblastoma: a Children's Cancer Group study.

PURPOSE: To assess the effect of local radiation administered to primary disease sites in children with high-risk neuroblastoma. MATERIALS AND METHODS: A total of 539 eligible patients were entered on protocol CCG-3891, consisting of chemotherapy, primary surgery, and 10 Gy of external beam radiation therapy (EBRT) to gross residual disease, followed by randomized assignment to continuation chemotherapy (CC) or autologous bone marrow transplantation (ABMT). ABMT patients received total body irradiation (TBI). RESULTS: Estimated event-free survival and overall survival at 5 years were 25% +/- 2% and 35% +/- 2%, respectively. Estimated 5-year locoregional recurrence rates were 51% +/- 5% and 33% +/- 7% for CC and ABMT patients (p = 0.004). For patients who received 10 Gy of EBRT to the primary, the addition of 10 Gy of TBI and ABMT decreased local recurrence compared with CC (22% +/- 12% and 52% +/- 8%, p = 0.022). EBRT did not increase acute toxicity, except for increased total parenteral nutrition administration. CONCLUSIONS: In combination with EBRT to the primary tumor site, the addition of 10 Gy of TBI as a component of high-dose chemotherapy with ABMT improved local control compared with CC without TBI. Results suggest a dose-response relationship for local EBRT. Short-term toxicity of local EBRT is limited.

Is residual confounding a reasonable explanation for the apparent protective effects of beta-carotene found in epidemiologic studies of lung cancer in smokers?

The results of three randomized trials of beta-carotene supplementation for the prevention of lung cancer among smokers are in contradiction to a large body of epidemiologic evidence for the reduction of risk of lung cancer among smokers with higher intake and/or higher serum levels of beta-carotene. Complicating this issue are widely noted negative associations between tobacco use and intake or serum levels of beta-carotene. Although observational studies attempt to control for reported smoking histories, the accuracy of self-reported smoking is uncertain; correlations as low as 0.5 between reported and true smoking exposure are not inconsistent with studies of biomarkers of cigarette exposure. The authors developed a simple statistical model for random errors in reported smoking (relative to true tobacco exposure) and assumed a modest (inverse) relation between true tobacco exposure and serum beta-carotene. Calculations from this model, combined with a model for lung cancer contemplated by Doll and Peto (J Epidemiol Community Health 1978;78:303-13), suggest that biases in assessment of smoking exposure between smokers with low versus high beta-carotene intake may plausibly explain much or all of the observed protective effect of high beta-carotene levels. Appropriate cohort studies of lung cancer in smokers, utilizing biomarkers of smoking, are needed and are presently ongoing.