Diet, obesity, and risk of fatal prostate cancer

Diet, nutrition and prostate cancer

Although much has been written, little is known about the causes of prostate cancer. Variations between populations in the incidence of invasive cancers, together with changes in the incidence of invasive cancers in migrants, have pointed to environmental (lifestyle) factors that might be amenable to intervention. Conversely, there is a lack of international variation in the prevalence of microscopic tumours, so the essential question is: what causes only some of the common microscopic tumours to become aggressive? Dietary factors hold the most promise in this regard and have been the subject of recent reviews. The strongest and most consistent effects are positive associations with animal products such as red meats, eggs and dairy foods, and possibly by implication, fat. Evidence of a protective effect of fruit and vegetables is weak and inconsistent, as is the relationship with vitamin A and carotenoids, such as beta-carotene. There are some interesting leads. Lycopene, the carotenoid found in tomatoes, has been reported to be protective; alpha-tocopherol supplementation has shown a protective effect in one intervention study; and vitamin D has been shown to be protective in a prospective study. Interest is also growing in phytoestrogens and the extent to which dietary manipulation with these and other phytochemicals might influence prostate cancer by modifying male sex hormone levels or actions. There is limited evidence of associations with obesity. It is not known whether these are related to a particular dietary pattern or to possible physiological effects on the male's hormonal milieu. Associations with lean body mass are likely to be related to the action of androgens during growth and development. Dietary and nutritional effects on prostate cancer do not appear to be strong, but they may be subtle and attenuated by measurement error. To explore these aspects further will require large prospective studies that include improved (repeated) dietary measurements and also blood sampling, so that genetic polymorphisms can be adequately investigated. Such studies are underway.

Diet and prostate cancer: a case-control study

A case-control study, performed in two towns of Serbia (Yugoslavia) from 1990 to 1994, comprised 101 patients with histologically confirmed prostate cancer and 202 hospital controls individually matched by age (+/-2 years), hospital admittance and place of residence. Dietary information was obtained by using a standard questionnaire. After adjustment for possible confounders, risk factors for prostate cancer appeared to be the highest tertile of protein (odds ratio (OR) = 13.54, 95% confidence interval (CI) = 2.38-77.13), saturated fatty acid (OR = 3.63, 95% CI = 1.03-12.79), fibre (OR = 4.02, 95% CI = 1.38-11.73), and vitamin B12 intake (OR = 2.07, 95% CI = 1.08-3.97); a protective effect was found for the highest tertile of alpha-tocopherol (OR = 0.15, 95% CI = 0.05-0.53), calcium (OR = 0.37, 95% CI = 0.14-0.99) and iron intake (OR = 0.34, 95% CI = 0.12-0.95). There were significant (P < 0.05) linear trends in the odds ratios for alpha-tocopherol, vitamin B12, calcium and iron. According to logistic regression step by step analysis, risk factors for prostate cancer were dietary intake of retinol equivalent (OR = 1.64, 95% CI = 1.01-2.67) and vitamin B12 (OR = 1.87, 95% CI = 1.15-3.05), and a protective effect was found for dietary intake of iron (OR = 0.40, 95% CI = 0.27-0.58).

Nutritional factors and prostate cancer: a case-control study of French Canadians in Montreal, Canada

The relationship between the risk of prostate cancer and dietary intake of energy, fat, vitamin A, and other nutrients was investigated in a case-control study conducted in Montreal (Quebec), Canada. French Canadians aged 35 to 84 years with a recent, histologically confirmed diagnosis of adenocarcinoma of the prostate were identified through the admission offices of five major francophone teaching-hospitals in Montreal from 1989 to 1993. Population-based controls matched for age (+/- five years), language, and place of residence were selected by a modified random-digit dialing method. The study included 232 cases and 231 controls. Information on dietary intake was collected by means of a quantitative dietary history. No association was evident between energy intake and the risk of prostate cancer. In contrast, there was some evidence of an inverse association with intake of total fat, animal fat, monounsaturated fat, and particularly saturated fat (odds ratio = 0.69, 95 percent confidence interval = 0.40-1.18, P = 0.05), while a nonsignificant positive association was found with polyunsaturated fat. In addition, high intake of retinol and vegetable protein (highest cf lowest quartile) was associated with reduced risk, but was not statistically significant. No associations were established between intake of other nutrients and risk. These patterns persisted after adjustment for a number of potential confounding factors.

How is individual risk for prostate cancer assessed?

A man's risk of developing prostate cancer is influenced by both genetic and nongenetic factors. Genetic factors are particularly important at younger ages, and the attributable risk of strong genetic factors could be as high as 43% among men less than 55 years of age; however, only about 9% of all cases may be directly attributable to a family history of prostate cancer. Race appears to be an important determinant of risk; African-American men are at high risk, whereas men of oriental ancestry are at lower risk. The bases of these racial differences remain obscure but may be related to hormonal differences. Modifiable risk factors are most important from a public health perspective. Diet or closely related factors appear to hold the most promise for prevention, although the precise factors are unknown. The strongest evidence indicates that some component of animal fat intake appears to act as a promoter of prostate cancer. Other dietary factors, including vitamin D, vitamin E, and beta-carotene and lycopene, may confer protection, but these require more study. Many but not all studies that have examined long-term effects of vasectomy suggest that this procedure may increase risk of prostate cancer, but whether this association is causal is not established. Occupational factors, smoking, and physical activity level do not appear to be major determinants of prostate cancer risk.

Prostate cancer screening

Prostate cancer is a common cancer and a leading cause of cancer death in men. It is potentially detectable at early, possibly curative stages through various combinations of testing, including DRE, PSA, and TRUS of the prostate. Still unproven is the effectiveness of prostate cancer treatment, and because of that lack of proof, the optimal screening strategies are also elusive. It is possible that what is known as prostate cancer today may be, in fact, multiple entities with different natural histories, different treatment needs, and, consequently, different screening strategies. The role of informed consent has been suggested as a means to involve patients in the decision process, especially because the literature presents an environment of intense controversy. It is hoped that the PIVOT trial or similar efforts and further research into the basic mechanisms of the disease will provide clearer answers in the future.

Nutrition and prostate cancer

Epidemiologic evidence on the relation between nutrition and prostate cancer is reviewed. Little is known about the etiology of prostate cancer, despite its prominence as the leading cancer among men in the United States. Rational mechanisms for dietary influences on prostate carcinogenesis, including effects on production or metabolism of androgenic hormones, have been proposed, but because few suitable animal models have been developed, the laboratory literature on diet and prostate cancer is sparse. Despite strong ecologic data and largely consistent case-control and cohort data on dietary fat and prostate cancer, the role of this nutrient remains unclear. Few studies, to date, have adjusted the results for caloric intake, and no particular fat component has been consistently implicated. A notable finding is a strong positive association with intake of animal products, especially red meats, but this in itself does not specifically implicate fat. Epidemiologic investigations on vitamin A and carotenoids are divided almost equally between studies showing positive and inverse associations. The evidence from these studies for a protective effect of fruits and vegetables on prostate cancer, unlike many other cancer sites, is not convincing. The data on other dietary components that have been examined with regard to prostate cancer etiology (cadmium, zinc, vitamins C and D, beverages, and legumes) are too incomplete at this time to draw any inferences as to their importance. The evidence for anthropometric associations with prostate cancer is weak. Whereas a clear association with obesity has not been shown, a positive relationship to muscle mass, though not yet established conclusively, further suggests the importance of androgens in this cancer.

Dietary factors and risk of prostate cancer: a case-control study in Ontario, Canada

The relationship between risk of prostate cancer and dietary intake of energy, fat, vitamin A, and other nutrients was investigated in a case-control study conducted in Ontario, Canada. Cases were men with a recent, histologically confirmed diagnosis of adenocarcinoma of the prostate notified to the Ontario Cancer Registry between April 1990 and April 1992. Controls were selected randomly from assessment lists maintained by the Ontario Ministry of Revenue, and were frequency-matched to the cases on age. The study included 207 cases (51.4 percent of those eligible) and 207 controls (39.4 percent of those eligible), and information on dietary intake was collected from them by means of a quantitative diet history. There was a positive association between energy intake and risk of prostate cancer, such that men at the uppermost quartile level of energy intake had a 75 percent increase in risk. In contrast, there was no clear association between the non-energy effects of total fat and monounsaturated fat intake and prostate cancer risk. There was some evidence for an inverse association with saturated fat intake, although the dose-response pattern was irregular. There was a weak (statistically nonsignificant) positive association between polyunsaturated fat intake and risk of prostate cancer. Relatively high levels of retinol intake were associated with reduced risk, but there was essentially no association between dietary beta-carotene intake and risk. There was no alteration in risk in association with dietary fiber, cholesterol, and vitamins C and E. Although these patterns were evident both overall and within age-strata, and persisted after adjustment for a number of potential confounding factors, they could reflect (in particular) the effect of nonrespondent bias.

A prospective study of weight, body mass index and other anthropometric measurements in relation to site-specific cancers

The association of weight, body mass index and other anthropometric measurements with cancer was investigated in a cohort of 7,840 men, examined and interviewed from 1965-1968 in Hawaii. After 23 years of follow-up, histologically confirmed incident cases of prostate (n = 306), colon (n = 289), lung (n = 236), stomach (n = 229) and rectal (n = 108) cancer were identified. Body weight was positively associated with prostate cancer. This direct association was stronger for cases diagnosed 11 or more years after examination than for those diagnosed earlier. A similar pattern was also present for the risk of colon cancer in association with weight and body mass index. For lung cancer, increased subscapular and triceps skinfold thickness were each associated with decreased risk with adjustment for cigarette smoking, but the inverse association did not persist as the time interval from exam to cancer diagnosis lengthened. There was no significant association between anthropometric measurements and stomach or rectal cancer.

Chemoprevention of prostate cancer

Primary prevention of prostate cancer is a relatively new concept. Through large-scale studies it is possible that we may be able to define better the risk for prostate cancer and identify those who would benefit from an intervention to lower their risk of disease. As risk for prostate cancer is better defined, a number of interventions may eventually be tested. Several interventions are sufficiently mature that they can be implemented in large-scale trials. Diet modification is an intervention that is ready for evaluation. It may also have additional benefits by decreasing mortality from other malignancies and cardiac disease. 5 alpha-reductase inhibitors are also ready for testing. The National Cancer Institute and its clinical cooperative groups have begun a large trial to assess finasteride in the prevention of prostate cancer.

Arachidonic acid metabolism in benign and malignant prostatic tissue in vitro: effects of fatty acids and cyclooxygenase inhibitors

Concentrations of fatty acids (FA) in prostatic tissue of patients with either benign or malignant prostatic disease have previously been shown to be significantly different. In particular, there was a significant reduction in arachidonic acid (AA, C20:4n-6) and docosapentaenoic acid (DPA, C22:5n-6) concentrations in malignant prostatic tissue (PCa) phospholipids (PL). It was suggested that the decreased AA concentration in PCa may be due to its increased metabolism via the cyclooxygenase (CO) and/or lipoxygenase (LO) pathways to produce eicosanoids such as prostaglandins (PGs) and/or leukotrienes (LTs) rather than an impairment in desaturase activity in situ. The eicosanoid production in benign prostatic tissue (BPH) and PCa was determined using [3H]AA. The only eicosanoid produced in significant amounts by either tissue was PGE2 and PCa converted radiolabelled AA to PGE2 at an almost 10-fold higher rate than BPH. PGE2 production from [3H]AA by PCa was investigated in the presence of oleic acid (OA, C18:1n-9), eicosapentaenoic acid (EPA, C20:5n-3), docosahexaenoic acid (DHA, C22:6n-3), dihomo-gamma-linolenic acid (DGLA, C20:3n-6), eicosatetraynoic acid (ETYA) and ketoprofen (KPN) respectively. OA was found to be the most effective inhibitor of PGE2 production by PCa compared with DHA, EPA, ETYA and KPN, while DGLA was the least effective. Diacylglycerol (DAG) formation from labelled AA by PCa was about 4-fold greater than in BPH. Such high levels of DAG may be a means of promoting tumorigenesis through activation of protein kinase C as found with phorbol esters which can be regarded as DAG analogues.

Cancer morbidity in alcohol abusers

Data on the association between alcohol abuse and cancer morbidity are scarce in large cohorts of non-hospitalised alcoholic men and women. Of 18,368 alcohol abusers who entered an outpatient clinic in Copenhagen during 1954-87, 18,307 were followed and their cancer incidence was compared with that of the total Danish population. On average the 15,214 men were observed for 12.9 years and the 3,093 women for 9.4 years. The overall morbidity of cancer was increased significantly. Of the men, 1,441 developed cancer [relative risk (RR) = 1.6; 95% confidence interval (CI) = 1.5-1.7], while 182 women did (RR = 1.5; 95% CI 1.3-1.8). Significantly increased incidences were found of cancer in the tongue, mouth, pharynx, oesophagus, liver, larynx, lung and pleura and secondary cancer. The women had significantly increased risk of cervical cancer (RR = 2.0; 95% CI 1.2-3.0). The men developed prostatic cancer significantly more frequently than expected (RR = 1.4; 95% CI 1.2-1.8). The risk of melanomas (RR = 0.5; 95% CI 0.2-0.8) was significantly lower than expected. The relative risks of cancer of the stomach, pancreas, kidney and endocrine system were only slightly increased. The study group did not develop more colonic (RR = 1.0; 95% CI 0.8-1.3) or rectal cancer (RR = 1.0; CI 0.7-1.3) than expected. The risk of breast cancer in women was slightly increased (RR = 1.3; 95% CI 0.9-1.7), but not statistically significant. Thus, the associations between alcohol and cancer of the upper digestive and respiratory tract and the liver are confirmed. In addition, this study indicates an increased occurrence of cancer of the prostate gland, pleura and uterine cervix in alcohol abusers.

Developmental estrogenization and prostatic neoplasia

The association of estrogens with benign prostatic hyperplasia and prostatic cancer has been widely studied, but no conclusive evidence exists for a role of estrogens in prostatic disease. This paper reviews the literature and describes studies which have sought to show a correlation of estrogens and alterations in the prostates of humans and experimental animal models. Using the developmentally estrogenized mouse model, we propose an alternative role for estrogens as a predisposing factor for prostatic diseases: estrogen exposure during development may initiate cellular changes in the prostate which would require estrogens and/or androgens later in life for promotion to hyperplasia or neoplasia. Thus, the critical time for estrogen action would be during the development of the prostatic tissue. We further suggest that estrogen-sensitive cells may remain in the prostate and be more responsive to estrogens later in life or less responsive to the normal controlling mechanisms of prostatic growth.

Obesity and cancer risk: a Danish record-linkage study

A cohort of 43,965 obese persons was accrued on the basis of discharge registrations from Danish hospitals, and incidence of cancer in the cohort was compared to that in the Danish population as a whole using indirect standardisation for age and period. Increased incidence was observed for cancer of the uterine corpus independently of age [114 cases, relative risk (RR) = 2.0, confidence interval 1.6-2.4], and for breast cancer in women above the age of 70 (133 cases, RR = 1.2). These findings are consistent with previous studies. In younger women, breast cancer occurred less frequently and ovarian cancer occurred more frequently than expected. Increased incidence was observed for cancers of the oesophagus (26 cases, RR = 1.9) and the liver (58 cases, RR = 1.9), probably reflecting an increased prevalence of excessive alcohol consumption in the cohort. Increased incidence was furthermore observed for cancers of the pancreas (101 cases, RR = 1.7), the prostate (96 cases, RR = 1.3) and the colon (195 cases, RR = 1.2), which may indicate the existence of risk factors which are common to obesity and to these cancers, for example, dietary habits. Kidney cancer was increased in women only. Overall, the incidence of cancer was increased by 16% in the cohort. The results were essentially unchanged by restriction to the subcohort of 8207 persons in whom obesity was the primary discharge diagnosis, and were also similar in the first year of follow-up after hospital discharge. Selection bias is, therefore, not likely to have influenced the results.

Occupational physical activity, socioeconomic status, and risks of 15 cancer sites in Turkey

A multiple-site case-control study of 15 cancers (stomach; colon; rectum; larynx; lung; melanoma; skin; female breast; male breast; cervix; ovary; uterus; prostate; testis; and bladder) was conducted to evaluate their association with occupational physical activity and socioeconomic status (SES). A hospital-based study population (3,486 male cases and 379 female cases, and 2,127 male and 244 female controls) was established in an oncological treatment center in Istanbul, Turkey, from 1979-84. Assessment of physical activity and SES was based on job titles held by the study subjects. Two measures of physical activity were developed based on energy expenditure and 'sitting time' during working hours. Observed risks were adjusted for age, smoking, and SES. Elevated risks were observed among workers who held sedentary jobs for cancers of the colon (odds ratio [OR] = 1.6), rectum (OR = 1.3), melanoma (OR = 1.9), male breast (OR = 1.4), prostate (OR = 5.0), and ovary (OR = 2.0). Cancers of the cervix and uterus showed significantly decreasing risks with decreased activity. Risks of cancers of the colon, rectum, larynx, ovary, and melanoma were enhanced after risks for physical activity indices were adjusted for SES, while the associations between physical activity and cancers of the prostate, cervix, and uterus were weakened after SES adjustment. Risks of melanoma rose significantly with both activity indices after SES adjustment.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of sex hormone levels in men as useful indices in hormone-related disorders

Because the determinants of serum sex hormone levels in men have been infrequently studied, we investigated the relation of several personal characteristics to serum levels of testosterone (T), dihydrotestosterone (DHT), estrone (E1), estradiol (E2) and sex hormone-binding globulin (SHBG) among 98 Japanese American men in Hawaii, aged 52-74. The SHBG levels and T/(E1 + E2) ratios decreased progressively with increasing body mass index. The SHBG levels were also inversely associated with hematocrit levels. Serum androgen and estrogen levels did not correlate with smoking, alcohol intake, serum cholesterol, serum uric acid and blood pressure. Some of the associations observed in the present study may be implicated in the etiology of hormone-related neoplasms in men.

Dietary fat, fatty acids and prostate cancer

International comparisons suggest a relationship between prostate cancer incidence and dietary fat, an inference supported by migration studies, the changing incidence rates and levels of animal fat consumption in Japan and the results from some case-control studies. Overall, however, epidemiological studies have been inconclusive, and although prostate cancer is one of the hormone-dependent tumors, evidence of interactions between dietary fats and male endocrine function is incomplete. Laboratory experimentation has shown that n-6 fatty acids stimulate and n-3 fatty acids inhibit human prostate cancer cells in culture; also, feeding diets rich in marine oils suppresses growth of these cells as solid tumors in athymic nude mice. These growth effects of polyunsaturated fatty acids appear to involve both prostaglandins and leukotrienes and to interconnect with autocrine regulation by epidermal growth factor-related polypeptides.

Diet and prostatic cancer: a case-control study in northern Italy

The relationship between intake of various indicator foods and beverages and risk of prostatic cancer was assessed in 271 cases of prostatic cancer and 685 hospital controls recruited in two areas of northern Italy, the province of Pordenone and the greater Milan area. Increased risks were found for more frequent intake of meat [odds ratio (OR) in the highest vs. lowest consumption tertile = 1.4, 95% confidence interval (CI) 1.0-2.0], milk (OR = 1.6, 95% CI 1.1-2.4), fresh fruit (OR = 1.4, 95% CI 1.0-2.1), and vegetables (OR = 1.4, 95% CI 0.9-2.2). After allowance for the reciprocal confounding effect of various dietary habits, only frequent intake of milk seemed to be a significant independent indicator of prostatic cancer risk. There was also a clue that the unfavorable influence of frequent intake of a few food items (i.e. meat, fish, liver, ham and salami, milk and butter, and retinol) may be greater or restricted to older individuals (i.e., > or = 70 yrs of age). In conclusion, the present study confirms the presence of a moderate adverse effect of high intake of foods of animal origin, chiefly milk, while it suggests that a diet rich in fresh fruit and vegetables does not convey a protection.

Essential fatty acid distribution in the plasma and tissue phospholipids of patients with benign and malignant prostatic disease

There is increasing evidence that essential fatty acids (EFA) may have a role to play in the aetiology of some types of cancer although their precise mode of action is unknown. Differences in the metabolism of EFA between patients with benign or malignant prostatic disease may help to elucidate their role in the latter. We have, therefore, measured the concentration of the essential fatty acids, and their metabolites, in the phospholipid fractions of both plasma and tissue, in patients with either benign or malignant prostatic disease. Comparison of the median concentration of fatty acids in each group (n = 10) revealed significant differences between them. The phospholipid component of total lipid was greater in malignant (P less than 0.04, unpaired t-test) than in benign tissue. The concentrations of linoleic acid (LA) and di-homo gamma linolenic acid (DGLA) in plasma and tissue were not different between the two groups of patients, but a significant reduction in arachidonic acid (ARA) (P less than 0.002, Mann-Whitney U-test) and docosapentaenoic acid (DPA) (P = 0.009) concentrations was observed in malignant tissue as compared to benign. Patients with malignant prostatic disease also had a significantly higher concentration of oleic acid in phospholipids from both plasma and prostatic tissue. The stearic to oleic acid ratio was similar in plasma but was significantly reduced in malignant tissue (P = 0.006). We suggest that the decreased arachidonic acid concentration in malignant tissue may be due to its increased metabolism, via the lipoxygenase and cyclooxygenase pathways to produce higher concentrations of eicosanoids, rather than an impairment in desaturase activity in situ.

Relation of body size to prognosis in lung cancer patients

A survival analysis was conducted among a sample of 463 men and 212 women with histologically confirmed lung cancer. Interview information from these patients was obtained from two population-based case-control studies of lung cancer conducted on the island of Oahu, Hawaii, between 1979 and 1985. The interview consisted of a complete tobacco history, and other demographic and lifestyle information. Records from the Hawaii Tumor Registry were reviewed for data on stage, histology, and follow-up status of these patients. Height, weight in early adulthood, and weight five years prior to diagnosis were inversely related to survival among women, after adjustment for age at diagnosis, stage, histology, ethnicity, and smoking status. No relationship of these variables to survival was found among men. The association of body size and the relative risk of death among women was strongest for patients with small cell cancer, although the association was not restricted to this cell type. The covariate-adjusted median survival times for female never-smokers below the 50th percentile of weight in early- and late-adulthood was at least twice as long as that for any other group (46 cf 17-23 months). There was no evidence for an interaction between weight in early adulthood and weight five years prior to diagnosis on the risk of death among women. Stage at diagnosis and education did not modify the association of the anthropometric variables and survival. These data suggest that weight and height may be associated with prognosis for women with lung cancer.

Prostate cancer

Prostate cancer is the most common malignancy in men and the second leading cause of cancer deaths. Although the mortality rate for prostate cancer has remained unchanged for 50 years, new advances have changed classic concepts in the diagnosis and management of patients with this disease. Our understanding of the anatomy and natural history of patients with prostate cancer has been enhanced. The ability to diagnose early stage prostate tumors has been improved by the introduction of prostate-specific antigen and transrectal ultrasound. Clinical staging of patients with prostate cancer has been refined, which has decreased adverse effects of inappropriate treatment. Modifications in the technique of radical prostatectomy have minimized the morbidity associated with this procedure, making it a more attractive therapeutic option. DNA ploidy analysis holds promise as a predictor of response to hormonal therapy. New agents are available to reduce adverse effects of hormonal therapy. In addition, traditional ideas about the timing of hormonal therapy and the use of total androgen blockade are being challenged. These changes may presage an improved quality of life and improve survival for patients with prostate cancer.

Adult dietary intake and prostate cancer risk in Utah: a case-control study with special emphasis on aggressive tumors

A population-based case-control study in Utah of 358 cases diagnosed with prostate cancer between 1984 and 1985, and 679 controls categorically matched by age and county of residence, were interviewed to investigate the association between dietary intake of energy (kcal), fat, protein, vitamin A, beta-carotene, vitamin C, zinc, cadmium, selenium, and prostate cancer. Dietary data were ascertained using a quantitative food-frequency questionnaire. Data were analyzed separately by age (45-67, 68-74) and by tumor aggressiveness. The most significant associations were seen for older males and aggressive tumors. Dietary fat was the strongest risk factor for these males, with an odds ratio (OR) of 2.9 (95 percent confidence interval [CI] 1.0-8.4) for total fat; OR = 2.2 (CI = 0.7-6.6) for saturated fat; OR = 3.6 (CI = 1.3-9.7) for monounsaturated fat; and OR = 2.7 (CI = 1.1-6.8) for polyunsaturated fat. Protein and carbohydrates had positive but nonsignificant associations. Energy intake had an OR of 2.5 (CI = 1.0-6.5). In these older men, no effects were seen for dietary cholesterol, body mass, or physical activity. There was little association between prostate cancer and dietary intake of zinc, cadmium, selenium, vitamin C, and beta-carotene. Total vitamin A had a slight positive association with all prostate cancer (OR = 1.6, CI = 0.9-2.4), but not with aggressive tumors. No associations were found in younger males, with the exception of physical activity which showed active males to be at an increased but nonsignificant risk for aggressive tumors (OR = 2.0, CI = 0.8-5.2) and beta-carotene which showed a nonsignificant protective effect (OR = 0.6, CI = 0.3-1.6). The findings suggest that dietary intake, especially fats, may increase risk of aggressive prostate tumors in older males.

Family aggregation of cancer of the prostate in Quebec: the tip of the iceberg

Cancer of the prostate is one of the most common cancers among males in North America. Although some causative factors have been suggested by several surveys, the etiology of this common cancer is poorly understood. In a case-control study of prostatic cancer in Greater Montreal, 21 of 140 patients with prostatic cancer (15.0%) gave a positive family history of the same cancer, as compared with two cases among 101 (2.0%) population-based controls. This indicates about an eightfold difference in occurrence of cancer of the prostate among first-degree family members of the case group with an odds ratio (OR) of 8.7 and 95% CI, 2.00-38.17. In this report we present the pedigrees of three families (two cases and one control) with four pathologically confirmed cases of cancer of the prostate in each family. This data suggest that a familial predisposition to prostatic cancer may become apparent in later decades of life. In these family aggregations, in addition to the genetic factors, environmental factors may also play an important role in the etiology of the same cancer among family members.

Effects of a fat-containing meal on sex hormones in men

The effect of a fat-containing meal on plasma sex steroid concentrations was investigated in normal men. After an overnight fast on two separate occasions, subjects ingested a liquid meal containing either a nonnutritive sweetener (control), or isocaloric meals of mixed calorie sources with either high-fat content or mixed carbohydrate and protein with minimal fat. The order of the meals was alternated. Blood samples were collected at 15-minute intervals and pooled each hour. Sampling began at 7:00 AM and the test meal was ingested at 8:00 AM. Sex steroids, including estrone, estradiol, testosterone, and dihydrotestosterone (DHT), sex hormone-binding globulin (SHBG) capacity, free testosterone concentration, and luteinizing hormone (LH) were determined by either specific radioimmunoassay or dialysis. The fat-containing meal, but not the nonnutritive or mixed carbohydrate and protein meal, resulted in a significant (P less than .01) reduction in total and free testosterone. Estrogens and luteinizing hormone were unaffected by either meal. This is the first documentation, to our knowledge, of the acute effect of a fat-containing meal on sex steroid concentrations in blood. Our observations suggest that a fat-containing meal reduces testosterone concentrations without affecting luteinizing hormone. This might indicate that fatty acids modulate testosterone production by the testes.

Milk consumption and cancer incidence: a Norwegian prospective study

Relationships between milk intake and cancer incidence were investigated after 11 1/2 years of follow-up of 15,914 individuals. A diagnosis of cancer was made in a total of 1,422 individuals. No association was established with total cancer incidence, in analyses adjusted for sex, age and residential characteristics. However, a strong positive association with milk consumption was observed for cancers of the lymphatic organs (odds ratio 3.4 for greater than or equal to 2 glasses per day vs less than 1; 95% confidence interval 1.4-8.2). An inverse association was found for cancer of the bladder. Kidney cancer and cancers of the female reproductive organs (except the uterine cervix) showed weak positive associations with milk intake.

Epidemiologic evidence regarding predisposing factors to prostate cancer

In 1990, prostate cancer will be the most common cancer diagnosed in U.S. men and will be the second-leading cause of cancer mortality in these men. One in ten U.S. men will develop prostate cancer in his lifetime. Twenty thousand prostate cancer cases occur each year in men under the age of 65. The average number of years of life lost for a man dying of prostate cancer is nine. In addition, both incidence and mortality of prostate cancer are increasing. A review of the literature regarding prostate cancer is timely in light of recent studies examining possible predisposing factors for this disease. In this review, a framework for understanding genetic and environmental factors which may predispose to prostate cancer is presented. The identification of factors which predispose to clinical prostate cancer offers the possibility of lowering the incidence and mortality of prostate cancer in the United States. Epidemiologic evidence regarding possible predisposing factors to prostate cancer is reviewed.

Diet and cancer. A review

Diet is one of the major causes of cancer. The epidemiologic data on which this conclusion is based has been derived from analytic epidemiologic studies, buttressed by descriptive (ecologic) epidemiology and studies in experimental animals. Although the evidence is not entirely consistent, high dietary fat intake appears to be a major cause of breast cancer, and more consistently, of colorectal cancer, and probably prostate cancer as well. Obesity is an important cause of endometrial cancer, and increases the risk of breast cancer in postmenopausal women, though increasingly there is evidence that suggests that obesity is protective for breast cancer in premenopausal women. There is inconsistent evidence that dietary fibre is protective for colorectal cancer, though good evidence that vegetable consumption is protective. Several studies have pointed to a protective effect of betacarotene for lung cancer, but betacarotene may be acting as an indicator of other protective factors in diet. Recommendations for dietary modification, congruent with recommendations for the prevention of cardiovascular and other chronic diseases, are now appropriate.

Energy balance, body size, and cancer

Increased energy intake and physical inactivity have been shown to heighten the risk of breast, large bowel, and other cancers. Large body size and fatness, as measured by adult stature, body weight and body mass indices, are positively related to a variety of cancers, including breast, colorectum, prostate, endometrium, kidney, and ovary, as well as to total cancer incidence or mortality in many investigations, although conflicting reports exist. Adult weight gain has also been specifically implicated in a few etiologic studies of breast and large bowel cancer. Furthermore, increased birthweight and childhood stature have been linked to increased risk of leukemia, lymphoma, osteogenic sarcoma, and central nervous system malignancies between infancy and young adulthood. Greater body weight also adversely affects breast cancer survival. These findings are complementary and support a role for positive energy balance in promoting human carcinogenesis. Potential mechanisms are discussed.

Cohort study of diet, lifestyle, and prostate cancer in Adventist men

Dietary and lifestyle characteristics were evaluated in relation to subsequent prostatic cancer risk in a cohort of approximately 14,000 Seventh-day Adventist men who completed a detailed lifestyle questionnaire in 1976 and who were monitored for cancer incidence until the end of 1982. During the 6-year follow-up period, 180 histologically confirmed prostatic cancers were detected among some 78,000 man-years of follow-up. Increasing educational attainment was associated with significantly decreased risk of prostate cancer in this study; age at first marriage was also inversely associated with risk, although this was not significant. There was no relationship between body mass index (as measured by Quetelet's Index) and risk. A history of prostate "trouble" was associated with a 60% increase in risk which was highly significant. Although there were suggestive relationships between increasing animal product consumption and increased risk, these results did not persist after accounting for the influence of fruit and vegetable consumption. Nor was exposure to the vegetarian lifestyle during the childhood years associated with alterations in subsequent risk. However, increasing consumption of beans, lentils and peas, tomatoes, raisin, dates, and other dried fruit were all associated with significantly decreased prostate cancer risk.

Beta-carotene and animal fats and their relationship to prostate cancer risk. A case-control study

A case-control study of 371 prostate cancer patients and comparable control subjects admitted to Roswell Park Memorial Institute (RPMI), Buffalo, New York, was conducted. Data were obtained from routine epidemiologic questionnaires administered to all patients on admission. An index of beta-carotene intake was computed based on the vitamin A activity of 27 fruits and vegetables included in a food frequency checklist. A similar measure of fat intake from meats was computed based on nine meats included in the checklist. Intake frequencies of common and alcoholic beverages also were studied. A significant age-adjusted and residence-adjusted protective effect for high levels of beta-carotene intake was observed (relative risk [RR], 0.60; 95% confidence interval [CI], 0.37 to 0.99). This effect was evident particularly among men 68 years of age and younger (RR, 0.30; 95% CI, 0.13 to 0.66), but not among subjects older than 68 years of age. A trend toward increased risk for fat intake was not significant. However, the reported usual consumption of high-fat milk was associated with increased risk (RR, 1.92; 95% CI, 1.05 to 3.50). A greater reported frequency of whole milk intake was similarly associated with increased risk. Men who reported drinking three or more glasses of whole milk daily had an RR of 2.49 (95% CI, 1.27 to 4.87), compared with men who reported never drinking whole milk. When these findings are evaluated in the context of other recent studies, the weight of the evidence appears to favor the hypothesis that animal fat intake is related to increased risk of prostate cancer.

Diet, nutritional status, and cancer risk in American blacks

About 35% (10-70%) of all cancers may be associated with nutritional causes (1). However, while natural or added substances in foods may be carcinogenic, nutritional deficiencies or excesses may promote carcinogenesis. We compared data from blacks and whites using dietary and nutritional status surveys in the United States to determine whether the poorer dietary patterns and nutritional status of American blacks may be associated with their higher incidence and mortality from certain cancers (compared with whites). Our review indicates that blacks eat more nitrate and animal foods and not enough fiber in relation to protein, fat, and carbohydrate. Blacks also have poorer nutritional status with respect to getting enough thiamine, riboflavin, vitamins A and C, and iron, to being obese (females), and to being underweight (males). This is in agreement with hypotheses regarding the interactions between diet and cancer (associations found in whites) and dose-response relationships reported for some cancers for which blacks have a higher incidence and mortality than whites. More large-scale prospective case-control and cohort studies are needed in both blacks and whites to elucidate the contribution of specific dietary and nutritional factors to the risk of specific cancers in these population groups. However, such studies must be preceded by methodological research to obtain more valid measures of dietary and nutritional status.

Health risks of obesity

Evidence implicating obesity as a risk-factor disease is critically reviewed. Possible reasons for the many conflicting findings are addressed. The classification of obesity, based upon the site of body fat distribution, and possible biologic mechanisms associating regional adiposity with morbidity, are discussed.

Body mass and prostatic cancer: a prospective study

Previous studies have suggested that increased body mass is associated with an increased risk of prostatic cancer, but these studies have been limited by the fact that they were based on a few simple measurements such as height and weight. Similar results were found in a prospective study of the incidence of prostatic cancer in a cohort of Japanese men born in 1900-19 and living in Hawaii. Further evaluation of the extensive anthropomorphic measurements made in this cohort suggested that the association between measures of body mass and prostatic cancer might be accounted for more by lean tissue than by fat tissue. There was a significant positive association of the risk of prostatic cancer with area of muscle in the arm but not with area of fat in the arm. Further research is needed on the biological mechanisms of carcinogenesis that may be related to both lean and fat tissue and the development of prostatic cancer.

Retrospective cohort mortality study of Roman Catholic priests

In order to test the hypothesis that Roman Catholic priests are at low risk for prostatic cancer because of their celibacy, a cohort of 10,026 men who were active or retired diocesan (parish) Roman Catholic priests in the United States on January 1, 1949 were followed until death, leaving the priesthood, or January 1, 1978. The overall standardized mortality ratio (SMR) was 103 and the SMR for cancer of the prostate was 81. Other interesting findings include increased SMRs for cancer of the larynx (147), cirrhosis of the liver (147), and diabetes (182) and decreased SMRs for lung cancer (59), emphysema (26), and suicide (13).

Case-control study of prostate cancer and socioeconomic factors

A total of 1,162 prostate cancer cases and 3,124 age-matched hospital controls from several U.S. hospitals were studied to identify associations between prostate cancer and life-style variables. Among white males, college education, professional occupation, and non-Jewish ethnicity were weakly associated with the risk of prostate cancer (ORs = 1.5, 1.8, and 1.3, respectively, P less than 0.01). These relationships retained statistical significance after adjustment for age, marital status, body mass, cigarette smoking, alcohol consumption, and physical activity in multiple logistic regression models. Among black males, similar, though nonsignificant, risk elevations were observed for education and occupation. Weak positive effects of borderline statistical significance were observed for high body mass, low physical exercise, and high serum cholesterol (in elderly males only), and a significant reduction in risk was noted for never married black males. Cigarette smoking and alcohol consumption were not related to the risk of prostate cancer.

The effect of nutritional factors on sex hormone levels in male twins

Dietary intake has been hypothesized as being associated with several hormonally related cancers including prostate, breast, ovarian, and endometrial cancer. Because diet may affect hormones directly, it is logical to examine the effects of dietary factors on hormone production and levels. Therefore, a set of 72 male MZ and 83 male DZ twin pairs was ascertained from the Utah birth certificates. A quantitative food frequency questionnaire was administered and blood samples were drawn for hormonal assays. Heritability estimates for hormonal levels were calculated indicating a range from no heritability for sex hormone binding globulin (SHBG), estrone, and testosterone glucuronide to 70% for androstanediol glucuronide and luteinizing hormone. To examine nutritional factors, the difference in hormone and SHBG levels between each MZ twin and his co-twin were correlated with the difference in nutrient intake. Weight and obesity were significantly correlated with plasma testosterone and follicle stimulating hormone. Fat intake showed a significant association with testosterone. Androstanediol glucuronide, a steroid that reflects tissue formation of dihydrotestosterone, was inversely correlated with caloric intake, theobromine and caffeine. Testosterone glucuronide exhibited significant correlations with calories and vitamin A. This study suggests that dietary intake affects plasma sex-steroid levels in men.

Caloric intake, body weight, and cancer: a review

The literature is reviewed for evidence concerning the relation between caloric intake, body weight, and cancer. Convincing experimental data regarding caloric intake and benign and malignant tumor incidence have been available since the 1940s and demonstrate that caloric restriction significantly reduces tumor incidence for a variety of tumor types in several animal models. Some epidemiological investigations provide evidence for a positive calorie-cancer association in humans, although it is difficult (in these studies) to separate the effects of calories per se from those of dietary fat. A larger number of investigations have evaluated body weight alone, and high relative body weight or high caloric intake has been associated with increased risk of cancer of the breast, colon, rectum, prostate, endometrium, kidney, cervix, ovary, thyroid, and gallbladder. In contrast, lung, bladder, and stomach cancers appear to be inversely associated with body weight, and some prospective studies of men demonstrate greater total cancer mortality among lean individuals. However, in their analyses, few of these latter investigations considered the effects of cigarette smoking, antecedent illness, or competing causes of death. While the relations between caloric intake, other dietary macronutrients (e.g., fat), and body weight are complex and require further investigation, a complete review of the data suggests that reducing caloric intake and relative body weight may lead to a considerable decrease in cancer risk in humans.