A prospective study on intake of animal products and risk of prostate cancer.

OBJECTIVE: Association between animal products and prostate cancer have been observed in numerous observational studies, but it is not clear whether the high fat content of these foods or some other component accounts for these associations. We examine these associations among 51,529 men who contributed detailed dietary data. METHODS: Participants of the Health Professionals Follow-Up Study completed a semiquantitative food-frequency questionnaire in 1986, and subsequently in 1990 and 1994. Other data on potential risk factors were collected at baseline and in subsequent questionnaires during follow-up. Between 1986 and 1996, 1897 total cases of prostate cancer (excluding stage A1) and 249 metastatic cancers were identified. We used pooled logistic regression for analyses of diet and prostate cancer. RESULTS: Intakes of total meat, red meat, and dairy products were not associated with risk of total or advanced prostate cancer. An elevated risk for metastatic prostate cancer was observed with intake of red meat (relative risk (RR)= 1.6 for top vs. bottom quintile comparison, 95% confidence interval (CI) = 1.0-2.5); this association was slightly attenuated after controlling for saturated and alpha-linolenic fatty acids (RR = 1.5, 95% CI = 0.88-2.5). Processed meats, bacon and beef, pork or lamb as a main dish each contributed to an elevated risk of metastatic prostate cancer. Dairy product intake increased risk of metastatic prostate cancer (RR = 1.4, 95% CI = 0.91-2.2 for top vs. bottom quintile comparison), but no association remained after controlling for calcium and other fatty acids. A high intake in both red meat and dairy product was associated with a statistically significant two-fold elevation in risk of metastatic prostate cancer, compared to low intake of both products; however, most of the excess risk could be explained by known nutritional components of these foods. CONCLUSIONS: Intakes of red meat and dairy products appear to be related to increased risk of metastatic prostate cancer. While known nutrients, such as calcium and fatty acids, may explain most of the dairy association observed, it appears that a portion of the risk of metastatic prostate cancer associated with red meat intake remains unexplained.

A population-based case-control study of carotenoid and vitamin A intake and ovarian cancer (United States).

OBJECTIVE: To evaluate the association between dietary intake of carotenoids and vitamin A and the incidence of ovarian cancer. METHODS: We conducted a population-based case-control study of ovarian cancer in Massachusetts and Wisconsin. Incident cases diagnosed between 1991 and 1994 were identified through statewide tumor registries. We selected community controls at random from lists of licensed drivers and Medicare recipients; 327 cases and 3129 controls were included in the analysis. Data were collected by telephone interview, which included an abbreviated food and supplement list to quantify typical consumption of carotenoids (lutein/zeaxanthin, alpha-carotene, beta-carotene), retinol and total vitamin A at 5 years prior to diagnosis in cases, or to a comparable reference date in controls. Results were adjusted for age, state, and other risk factors. RESULTS: Participants with the highest dietary intake of lutein/zeaxanthin (> or =24,000 microg/week) experienced a 40% lower risk of ovarian cancer (95% CI = 0.36-0.99) compared to those with the lowest intake. Intake of alpha-carotene, beta-carotene, retinol and total vitamin A was unrelated to risk. Among foods, we observed non-significantly lower risks with high consumption of spinach, carrots, skim/lowfat milk and liver. CONCLUSION: These results support previous findings suggesting an inverse relationship between carotenoid intake and ovarian cancer risk.

Bowel movement, use of laxatives and risk of colorectal adenomatous polyps among women (United States).

BACKGROUND: Infrequent bowel movements and use of laxatives have been hypothesized to increase risk of colorectal neoplasia. However, the few existing epidemiologic studies in humans have been inconclusive. PURPOSE: To investigate prospectively the associations of bowel movement frequency and laxative use with the occurrence of adenomatous colorectal polyps in women. METHODS: A total of 17,400 women 36-61 years of age, without previous diagnosis of cancer or polyps, responded to a mailed questionnaire in 1982 that assessed bowel movement frequency and use of laxatives and had an endoscopy between 1984 and 1996. Between 1984 and 1996, 906 cases of adenomatous polyps (496 classified as small (< 1 cm), 358 classified as large (> or = 1 cm) and 52 unclassified) were documented. Relative risks (RRs) of adenomas and 95% confidence intervals (CIs) were calculated using logistic regression. RESULTS: After controlling for adenoma risk factors, the multivariate RRs associated with having bowel movements every third day or less compared to once daily were 0.9 (95% CI: 0.7-1.2) for total colorectal adenomas, 1.0 (95% CI: 0.7-1.5) for large adenomas and 1.0 (95% CI: 0.7-1.3) for adenomas of the colon only. The multivariate RRs associated with weekly to daily laxative use compared to never use were 0.9 (95% CI: 0.7-1.1) for total colorectal adenomatous polyps, 1.0 (95% CI: 0.7-1.5) for large adenomas and 0.8 (95% CI: 0.6-1.2) for colon adenomatous polyps only. CONCLUSION: These findings do not support an association between infrequent bowel movement or laxative use and risk of colorectal adenomas.

Lower levels of physical functioning are associated with higher body weight among middle-aged and older women.

OBJECTIVE: To compare levels of physical function, across levels of body mass index (BMI), among middle- to older-aged women. DESIGN: Cross-sectional study. Physical function, body weight and other covariates were measured in 1992. SUBJECTS: 56510 women aged 45-71 y, free of cardiovascular disease and cancer, participating in the Nurses' Health Study. MAIN OUTCOME MEASURES: The four physical function scores on the Medical Outcomes Study (MOS) Short Form-36 (SF36) Health Survey: physical functioning, vitality, bodily pain and role limitations. RESULTS: After adjusting for age, race, smoking status, menopausal status, physical activity and alcohol consumption, there was a significant dose-response gradient between increasing levels of BMI in 1992 and reduced function. For example, women with a BMI between 30-34.9 kg/m2 averaged: 9.0 point lower physical functioning score (95% Confidence interval (CI) -9.5, -8.5), 5.6 point lower vitality score (95% CI: -6.1, -5.1), and 7.0 point lower freedom from pain score (95% CI: -7.6, -6.4). These declines represent an approximate 10% loss of function compared to the reference category of women with BMIs ranging from 22.0-23.9 kg/m2. For the same BMI comparison, heavier women were at 66% increased risk of limitations in ability to work or perform other roles (RR = 1.66; 95% odds ratio (OR) CI: 1.56, 1.76). These findings were replicated when the sample was restricted to women who had maintained their BMI over a ten year period. CONCLUSIONS: In addition to increasing risk of chronic health conditions, greater adiposity is associated with lower every day physical functioning, such as climbing stairs or other moderate activities, as well as lower feelings of well-being and greater burden of pain.

The epidemic of prostate cancer and the medical literature: a causal association?

The diagnosis of prostate cancer has undergone an unprecedented recent increase, while mortality has increased much more slowly. We examined new prostate cancer diagnoses from 1987-1992 in a nationwide prospective cohort study of 51 529 men enrolled in the Health Professionals Follow-up Study, a population likely to be medically sophisticated and thus early to adopt medical innovations. The age-adjusted incidence of prostate cancer rose approximately 2(1/2) fold during the study period. Nearly all of the increase occurred among organ-confined tumors, with a smaller increase for regionally-advanced tumors and none for metastatic tumors. Using a Poisson regression model of newly-diagnosed cancers, we found organ-confined cancers rose abruptly by 86% (95% CI: 36-256%; P=0.0001) and regionally-advanced tumors by 73% (95% CI:12-267%; P=0.01) after March, 1991, when a study advocating screening using the prostate specific antigen (PSA) was published in the New England Journal of Medicine. The recent increase in the incidence of prostate cancer is probably due to the increased PSA screening of asymptomatic men, resulting in the diagnosis of large numbers of men with early-stage disease from 1990 onward. Despite ongoing debate over the value of PSA screening, the rate of diagnosis accelerated sharply after the publication of a well-publicized but inconclusive study advocating screening. In a context of growing disease awareness, well-publicized research reports may result in unexpectedly amplified acceptance into medical practice.