Physical activity and risk of Parkinson's disease: a prospective cohort study.

BACKGROUND: Despite the fact that Parkinson's disease is the second most common neurodegenerative disease, little is known about risk factors for the disease. Laboratory experiments indicate that physical activity may have a neuroprotective effect; however, there are few data on whether physical activity is associated with decreased risk of Parkinson's disease. AIM: To investigate the relationship between physical activity and Parkinson's disease in 10,714 men (mean age, 67.6 years) from the Harvard Alumni Health Study, who were diagnosed as free of self-reported Parkinson's disease in 1988. METHODS: Physical activity was assessed in 1988 by asking about the daily number of blocks walked and stairs climbed, and participation in sports and recreational activities in the past week. Energy expenditure was then estimated and men were categorised into four groups: < 1000, 1000-1999, 2000-2999 or > or = 3000 kcal/week. In addition, physical activity data were available for three past time points: during college, 1962 or 1966, and 1977. Incident cases of Parkinson's disease occurring after 1988 (n = 101) were identified through a follow-up health questionnaire in 1993 and death certificates obtained until 1997. RESULTS: In multivariate analyses, the relative risks (RR) for Parkinson's disease associated with < 1000, 1000-1999, 2000-2999 and > or = 3000 kcal/week of physical activity were 1 (referent), 1.15 (95% confidence interval (95% CI) 0.71 to 1.88), 0.92 (0.50 to 1.71) and 0.63 (0.36 to 1.12), respectively; p for trend was 0.12. When walking was examined separately, somewhat lower, but not significant, risks were observed for Parkinson's disease. The multivariate RRs (95% CI) for walking < 5, 5-10, 10-20 and > 20 km/week were 1 (referent), 0.67 (0.37 to 1.23), 0.81 (0.50 to 1.31) and 0.72 (0.39 to 1.34), respectively; p for trend was 0.26. Analyses that considered physical activity at other time points before 1988 did not show any significant associations. CONCLUSIONS: These data do not strongly support the hypothesis that physical activity lowers the risk of Parkinson's disease. However, as the number of patients with Parkinson's disease in this study was not large, statistical power may have been limited and further large studies are needed to provide additional data.

Quetelet's index and risk of colon cancer in college alumni.

BACKGROUND: While previous studies suggest that overweight, middle-aged men may face increased risk of colon cancer, it is unclear whether their weights as young adults influence this risk. It is also unknown whether their level of physical activity affects their risk of developing colon cancer. PURPOSE: To determine the relationship between being overweight in middle-age or young adulthood and colon cancer risk, we prospectively studied alumni of Harvard University. We also investigated whether being overweight influences risk differently for men with different levels of physical activity. METHODS: In 1962 or 1966 (1962/1966), alumni completed questionnaires on weight, height, other sociodemographic characteristics, and medical history. We obtained information on weight and height at college entry from university archives. Alumni (n = 17,595) were followed from 1962/1966 to 1988 for colon cancer occurrence, ascertained from follow-up questionnaires in 1977 and 1988 and death certificates. RESULTS: Between 1962/1966 and 1988, 302 cases of colon cancer were diagnosed. Colon cancer risk increased with higher levels of Quetelet's index (weight [kg]/height [m]2) in 1962/1966. Relative risk per unit increase, adjusted for age, physical activity, and parental history of cancer, was 1.08 (95% confidence interval [CI], 1.04-1.13). Quetelet's index at college entry did not predict risk as well (adjusted relative risk per unit increase, 1.05; 95% CI, 1.00-1.10). The heaviest fifth of alumni during both college time and in 1962/1966 had almost two and one-half times the risk of the lightest fifth of alumni (adjusted relative risk, 2.40; 95% CI, 1.40-4.13). When alumni were classified according to activity level in 1962/1966, higher levels of Quetelet's index were significantly associated with colon cancer risk only among those who were less active. CONCLUSIONS: Overweight during middle-age or young adulthood is associated with higher colon cancer risk; in overweight, physically active men, however, the risk of colon cancer may not be increased.

Oral contraceptives as related to cancer and benign lesions of the breast.

We conducted a case-control study to search for any relationship between use of oral contraceptives and development of breast cancer or benign breast disease. Women less than 50 years old with these diseases were matched with 2 controls by age, race, religion, and hospital. Home interviews elicited information on oral contraceptive use and other host and environmental factors. The study population comprised 1,770 women, including 452 with breast cancer and 446 with benign breast disease. The relative risk of developing cancer or benign disease was measured by matched set and summary chi-square analyses. Although the relative risk of developing breast cancer among "ever-users" of oral contraceptives was 1.1, the risk among women using oral contraceptives for 2-4 years was 1.9 (significantly increased). This risk estimate reached 2.5 for the 2- to 4-year users if they were still taking oral contraceptives when entered into study. Moreover, prior biopsy for benign breast disease increased the cancer risk among long-term users by as much as 11-fold. The relative risk of breast cancer did not vary by age, interval since first use, earliest year of use, or interval since last use. These results could be interpreted to indicate that oral contraceptives did not induce breast cancer but may have accelerated the growth rate of preexisting breast cancer. The relative risk of developing benign breast disease among ever-users of oral contraceptives was 0.8 (significantly reduced); it decreased with longer duration of use until it reached 0.2 for women who took these hormones 8 years or more. The relative risk of benign breast was not affected by earliest year of use or interval since last use. We concluded that oral contraceptives reduced the incidence of benign breast disease, but that use of steroid hormones is ill-advised for women with already established benign breast disease.

PIP: A 3-year case-control study of 1770 women under age 49 from the San Francisco Bay area, who were admitted to area hospitals with newly diagnosed breast cancer or with benign noninflammatory breast lesions, is reported. There were 452 with breast cancer, 446 with benign breast disease, 433 with other medical conditions, and 439 with other surgical conditions. Detailed information was obtained concerning each subject's contraceptive practices, menstrual and obstetric experiences, hormone use, medical and surgical history, and family history of breast cancer. Those without breast disease were selected as suitable controls concerning risk factors. In all instances the risk of breast disease was compared between women who had or were using oral contraceptives and others. Current users of oral contraceptives were 16% of patients with breast cancer and 13% of control patients. Contraceptive users were 9% of patients with benign breast disease. 1/2 of those using oral contraceptives had done so for 2 years or less. Only 15% of those who used these drugs had done so for over 6 years. Relative risk for all age groups of developing breast cancer was estimated to be increased by 10% among oral contraceptive users. The risk was less in older patients. With duration of oral contraceptive use, risk was significant only for the 2-4 year users in whom it was increased twofold (p less than .01). Relative risks were the same with the different dose levels of contraceptive compounds. Among ever-users, cancer risk was much greater (six to elevenfold) for women with prior history of biopsy for benign breast disease, particularly among those who had used oral contraceptives more than 6 years. Other contraceptive measures are recommended for such women. Observation for long-term effects should include study of type-specific benign disease as related to use of the hormones and later development of cancer. It may be that use of oral contraceptives accelerated the growth rate of preexisting subclinical malignant lesions and that after 2 years these lesions reach the level of clinical recognition, all being diagnosed within the next 2 years.

Physical activity and risk of developing colorectal cancer among college alumni.

The assessment of physical activity at a single time to evaluate its association with cancer may be limited, since such a measure may not adequately reflect activity over the long term. To overcome this limitation, we studied 17,148 Harvard alumni aged 30-79 years who were followed prospectively for the occurrence of colon cancer (n = 225) and rectal cancer (n = 44) from 1965 through 1988. Physical activity, based on self-reported stair climbing, walking, and sports play, was assessed in either 1962 or 1966 (1962/1966) and again in 1977. The increased activity evaluated using either assessment (1962/1966 or 1977) taken alone was not associated with risk of colon cancer. However, alumni who were highly active (energy expenditure of greater than 2500 kilocalories/wk) at both assessments had half the risk of developing colon cancer relative to those who were inactive (less than 1000 kilocalories/wk) at both assessments (age-adjusted rate ratio = 0.50; 90% confidence interval = 0.27-0.93), whereas those who were moderately active (1000-2500 kilocalories/wk) at both assessments had an age-adjusted rate ratio of 0.52 (90% confidence interval = 0.28-0.94). We conclude that either consistently higher levels of activity are necessary to protect against colon cancer or combining two assessments increased the precision of physical activity measurement. We found no evidence that increased physical activity protected against rectal cancer.

Characteristics in youth indicative of adult-onset Hodgkin's disease.

From the college entrance health data of 50,000 male former students, the records of 45 who eventually died of Hodgkin's disease were compared with those of 180 surviving classmates with reference to certain indicator characteristics. Risk ratios of Hodgkin's disease tended to be lower for men who had experienced various common contagious diseases in childhood. This reduced incidence of clinical contagions may signify that: 1) Inadequate early challenge of immune mechanisms left subjects more susceptible to later Hodgkin's disease, whether or not it is of infectious origin; 2) heightened immune mechanisms that led to subclinical attacks of early contagious diseases promoted an autoimmune response that evolved as Hodgkin's disease; or 3) early childhood infections eliminated some subjects who otherwise would have attended college and ultimately developed adult-onset Hodgkin's disease. Also, Hodgkin's disease risk was higher for students who had reported early death of a parent, particularly from cancer. Moreover, the risk tended to be increased among collegians who were obese, heavy cigarette smokers, and coffee drinkers. None of these indicator characteristics was associated with 89 fatal lymphomas of other types that occurred in the same study population.

Early precursors of site-specific cancers in college men and women.

Physical and social characteristics recorded at college physical examination and reported in subsequent questionnaires to alumni in 1962 or 1966 by 50,000 former students from Harvard University and the University of Pennsylvania were reviewed for their relationship to major site-specific cancer occurrence. The records of 1,359 subjects who died with a major site-specific cancer in a 16- to 50-year follow-up period and of 672 subjects who reported such a cancer by mail questionnaire in 1976 or 1977 were compared with those of 8,084 matched classmates who were known to be alive and free of cancer at the time subjects with cancer had died or had been diagnosed. Cigarette smoking, as reported both in student years and years as alumni, predicted increased risk for cancers of the respiratory tract, pancreas, and bladder. Student coffee consumption was associated with elevated risk for leukemia, but it was unrelated to cancers of the pancreas and bladder. Male students with a record of proteinuria at college physical examination experienced increased risk of kidney cancer, and those with a history of tonsillectomy experienced increased risk of prostate cancer. Students who at college entrance reported occasional vague abdominal pain were at elevated risk for pancreatic and colorectal cancers in later years. Increased body weight during college was associated with increased risks of kidney and bladder cancers, whereas for alumni this index was associated only with kidney cancer. Increased weight-for-height during college (but not in 1962 or 1966) predicted increased occurrence of female breast cancer. Jewish students experienced elevated risk for subsequent cancers of the female breast, colon, and combined colorectum. These and other findings are presented as clues deserving further exploration for any etiologic significance that they may hold for the cancer sites studied.

Serum levels of prostate-specific antigen among Japanese-American and native Japanese men.

BACKGROUND: Fourfold to sixfold higher prostate cancer rates in Japanese-American men in the United States compared with Japanese men in Japan have been cited to support a role for environmental risk factors in the etiology of the disease. To examine the hypothesis that part or all of the elevated prostate cancer rates in Japanese-American men may reflect more intensive prostate cancer screening in the United States than in Japan, we compared prostate-specific antigen (PSA) levels in community-based samples of serum from men without prostate cancer. METHODS: Japanese-American men aged 40-85 years and native Japanese men aged 40-89 years with no history of prostate cancer provided sera, respectively, in the United States from March 1990 through March 1992 (n = 237) or in Japan from January 1992 through December 1993 (n = 3522). Age-specific PSA levels were used to estimate the prevalences of undetected prostate cancer in the two populations. RESULTS: Age-specific mean PSA levels were significantly lower in Japanese-Americans than in native Japanese (two-sided P<.001). The prevalence of an elevated PSA level increased with age in both populations and exceeded 5% among men aged 60 years or more. Combined with data on prevalence of detected prostate cancer in the two populations, our data suggest that some 10.0% of Japanese-Americans aged 75 years have prostate cancer, with 31% of that fraction remaining undiagnosed. The corresponding estimates in Japan are a total cancer prevalence of 5.4%, of which 81% has not been detected clinically. CONCLUSIONS: The total cancer prevalence ratio 10.0/5.4 = 1.9 (95% confidence interval = 1.5-2.3) in Japanese-American men compared with Japanese men in Japan suggests an increased risk for Japanese-American men, but of less magnitude than the fourfold to sixfold increase indicated by the incidence data.

Epithelial ovarian cancer and the ability to conceive.

Relationships between ovarian cancer and ability to conceive were explored in a case-control study of 188 women with histologically confirmed epithelial ovarian cancer and 539 control women in the San Francisco Bay Area. Control women consisted of two groups: those hospitalized without cancer, matched to cases by age, race, and hospital of diagnosis (n = 280); and those selected from the general population by random digital dialing, matched to cases by age, race, and telephone prefix (n = 259). Ovarian cancer risk among nulliparous (but not parous) women was positively associated with a history of unsuccessful attempts to conceive, of physician-diagnosed infertility, and of doubts about ability to conceive. Among all women, risk increased with increasing years of unprotected intercourse (P value for trend = 0.02). Risk among women having 10 or more yr of unprotected intercourse was 1.8 relative to that among women having less than 2 such yr (P = 0.01). This association was independent of parity, oral contraceptive use, and estimated years of ovulation, each associated with ovarian cancer. Further, duration of unprotected intercourse combined multiplicatively with each of these latter characteristics in increasing ovarian cancer risk. For example, while cancer risk exhibited a 2-fold range from lowest to highest years of unprotected intercourse and a 4-fold range from lowest to highest years of ovulation, risk among women in the highest joint category of these characteristics was 8 times that of women in the lowest category. We believe that some abnormality of ovulation that reduces the likelihood of conception plays a role in epithelial ovarian cancer.

Physical activity and coronary heart disease in men: The Harvard Alumni Health Study.

BACKGROUND: The quantity and intensity of physical activity required for the primary prevention of coronary heart disease (CHD) remain unclear. Therefore, we examined the association of the quantity and intensity of physical activity with CHD risk and the impact of other coronary risk factors. METHODS AND RESULTS: We followed 12 516 middle-aged and older men (mean age 57.7 years, range 39 to 88 years) from 1977 through 1993. Physical activity was assessed at baseline in kilojoules per week (4.2 kJ=1 kcal) from blocks walked, flights climbed, and participation in sports or recreational activities. During follow-up, 2,135 cases of incident CHD, including myocardial infarction, angina pectoris, revascularization, and coronary death, occurred. Compared with men expending <2,100 kJ/wk, men expending 2,100 to 4,199, 4,200 to 8,399, 8,400 to 12,599, and >/=12,600 kJ/wk had multivariate relative risks of 0.90, 0.81, 0.80, and 0.81, respectively (P: for trend=0.003). When we considered the independent effects of specific physical activity components, only total sports or recreational activities (P: for trend=0.042) and vigorous activities (P: for trend=0.02) were inversely associated with the risk of CHD. These associations did not differ within subgroups of men defined by coronary risk factors. Finally, among men with multiple coronary risk factors, those expending >/=4,200 kJ/wk had reduced CHD risk compared with men expending <4,200 kJ/wk. CONCLUSIONS: Total physical activity and vigorous activities showed the strongest reductions in CHD risk. Moderate and light activities, which may be less precisely measured, showed nonsignificant inverse associations. The association between physical activity and a reduced risk of CHD also extends to men with multiple coronary risk factors.

Physical activity and coronary heart disease risk in men: does the duration of exercise episodes predict risk?

BACKGROUND: Physical activity is associated with a decreased risk of coronary heart disease (CHD). However, it is unclear whether the duration of exercise episodes is important: Are accumulated shorter sessions as predictive of decreased risk as longer sessions if the same amount of energy is expended? METHODS AND RESULTS: In the Harvard Alumni Health Study, we prospectively followed 7307 Harvard University alumni (mean age 66.1 years) from 1988 through 1993. At baseline, men reported their walking, stair climbing, and participation in sports or recreational activities. For each of the latter activities, they also reported the frequency and average duration per episode. During follow-up, 482 men developed CHD. In age-adjusted analysis, a longer duration of exercise episodes predicted lower CHD risk (P: trend=0.04). However, after total energy expended on physical activity and potential confounders was accounted for, duration no longer had an independent effect on CHD risk (P: trend=0.25); that is, longer sessions of exercise did not have a different effect on risk compared with shorter sessions, as long as the total energy expended was similar. In contrast, higher levels of total energy expenditure significantly predicted decreased CHD risk in both age-adjusted (P: trend=0.009) and multivariate (P: trend=0.046) analyses. CONCLUSIONS: These data clearly indicate that physical activity is associated with decreased CHD risk. Furthermore, they lend some support to recent recommendations that allow for the accumulation of shorter sessions of physical activity, as opposed to requiring 1 longer, continuous session of exercise. This may provide some impetus for those sedentary to become more active.

The role of physical exercise in the occurrence of Parkinson's disease.

A case-control study of Parkinson's disease and physical exercise was conducted in a cohort of 50,002 men who attended Harvard College (Cambridge, Mass) or the University of Pennsylvania (Philadelphia) between 1916 and 1950 and were followed up in adulthood for morbidity and mortality data. Cases of Parkinson's disease were identified from responses to mailed questionnaires and death certificates through 1978. Four controls from the same population were selected for each case. The association between physical activity at the time of college and subsequent risk of Parkinson's disease was evaluated for 137 cases and 548 controls, whereas the data on physical activity in adulthood before the disease occurrence was available only for 94 of these cases. Having belonged to a varsity team or having done regular physical exercise in college was associated with a lower nonsignificant risk of Parkinson's disease. In adulthood, practice of moderate or heavy sports was linked to a reduced risk, although more precise analysis revealed that there was only a modest nonsignificant reduction in risk for subjects who do a moderate amount of physical exercise, but this negative association disappears at higher levels of physical expenditure. These results, which require further confirmation, are compatible with a slight protective effect of physical exercise on the risk of Parkinson's disease, although the lack of association cannot be refuted.

Vegetables, fruits, legumes and prostate cancer: a multiethnic case-control study.

The evidence for a protective effect of vegetables, fruits, and legumes against prostate cancer is weak and inconsistent. We examined the relationship of these food groups and their constituent foods to prostate cancer risk in a multicenter case-control study of African-American, white, Japanese, and Chinese men. Cases (n = 1619) with histologically confirmed prostate cancer were identified through the population-based tumor registries of Hawaii, San Francisco, and Los Angeles in the United States and British Columbia and Ontario in Canada. Controls (n = 1618) were frequency-matched to cases on ethnicity, age, and region of residence of the case, in a ratio of approximately 1:1. Dietary and other information was collected by in-person home interview; a blood sample was obtained from control subjects for prostate-specific antigen determination. Odds ratios (OR) were estimated using logistic regression, adjusting for age, geographic location, education, calories, and when indicated, ethnicity. Intake of legumes (whether total legumes, soyfoods specifically, or other legumes) was inversely related to prostate cancer (OR for highest relative to lowest quintile for total legumes = 0.62; P for trend = 0.0002); results were similar when restricted to prostate-specific antigen-normal controls or to advanced cases. Intakes of yellow-orange and cruciferous vegetables were also inversely related to prostate cancer, especially for advanced cases, among whom the highest quintile OR for yellow-orange vegetables = 0.67 (P for trend = 0.01) and the highest quintile OR for cruciferous vegetables = 0.61 (P for trend = 0.006). Intake of tomatoes and of fruits was not related to risk. Findings were generally consistent across ethnic groups. These results suggest that legumes (not limited to soy products) and certain categories of vegetables may protect against prostate cancer.

Serum androgens and sex hormone-binding globulins in relation to lifestyle factors in older African-American, white, and Asian men in the United States and Canada.

Differences in endogenous androgen levels have been hypothesized to explain ethnic differences in prostate cancer risk. To examine this hypothesis, we gathered data on serum concentrations of androgens and sex hormone-binding globulin (SHBG) in healthy older men from four ethnic groups at different levels of prostate cancer risk. As part of a population-based case-control study of prostate cancer we conducted in California, Hawaii, and Vancouver, Canada, 1127 African-American, white, Chinese-American, and Japanese-American control men, mostly ages 60 years or older (mean age, 69.9 years) provided information on various lifestyle factors and donated an early morning fasting blood sample between March 1990 and March 1992. We used these data to examine the distributions of serum androgens [testosterone (total, free, and bioavailable), dihydrotestosterone (DHT)], the ratio of DHT to total testosterone (DHT:testosterone ratio), and SHBG in these four ethnic groups. We also assessed correlations between concentrations of these measures with age, body size, physical activity, and other personal characteristics, and we evaluated ethnic differences in concentrations of androgens and SHBG after adjusting for these characteristics. In each of the four ethnic groups, concentrations of free and bioavailable testosterone declined with age, whereas SHBG concentrations increased with age. Age-adjusted concentrations of all androgen measures and SHBG decreased with increasing levels of Quetelet's index. After adjustment for age and Quetelet's index, androgens and SHBG showed no clear and consistent relationships to physical activity, alcohol consumption, or tobacco use. DHT:testosterone ratio was higher in men reporting a history of benign prostate disease than in men without such a history, and higher in vasectomized men than in nonvasectomized men. SHBG concentrations were higher in men reporting one or more first-degree relatives with prostate cancer than in men without such a family history. After adjustment for age and Quetelet's index, the levels of total and bioavailable testosterone were highest in Asian-Americans, intermediate in African-Americans, and lowest in whites. However, the DHT:testosterone ratio was highest in African-Americans, intermediate in whites, and lowest in Asian-Americans, corresponding to the respective incidence rates in these groups and providing indirect evidence for ethnic differences in 5alpha-reductase enzyme activity.

Sense of exhaustion and coronary heart disease among college alumni.

Vital exhaustion, defined as a combination of fatigue, lack of energy, feelings of hopelessness, loss of libido, and increased irritability, has been proposed as a risk indicator for the development of coronary heart disease (CHD). It is unclear if the association between vital exhaustion and CHD is independent of sleep behavior, depression, and physical activity. We ascertained sense of exhaustion among 5,053 male college alumni who were free of cardiovascular disease, cancer, and chronic obstructive pulmonary disease by asking, "How often do you experience sense of exhaustion (except after exercise)?" on a health survey in 1980. Eight hundred fifteen men died during 12 years of follow-up, 25% due to CHD. After adjustment for age, body mass index, smoking status, and history of physician-diagnosed diabetes and hypertension, frequent sense of exhaustion was associated with a twofold increase in CHD mortality (rate ratio 2.07; 95% confidence interval 1.08 to 3.96). After additional adjustment for insomnia, sleep duration, use of sleeping pills and tranquilizers, physical activity, history of physician-diagnosed depression, and alcohol intake, the rate ratio was not appreciably altered; however, the association now was of borderline significance (rate ratio 2.06; 95% confidence interval: 0.98 to 4.36) because there were only 10 deaths from CHD among men who were frequently exhausted. In a prospective observational study, frequent sense of exhaustion appeared to be independently associated with increased risk of CHD mortality in men.

Accuracy of the College Alumnus Physical Activity Questionnaire.

The validity and reproducibility of the Physical Activity Index from the College Alumnus Questionnaire (PAI-CAQ) were determined in 78 men and women (21-59 yr) with a broad range of physical activity habits. The PAI-CAQ was computed as the sum of energy expended in stair climbing, walking, and sports and recreational physical activity recalled from the past week. Data were validated against measures of cardiorespiratory fitness, body fatness, motion detection, and physical activity records. All physical activity was recorded by participants for six 48-hour periods. Each day of the week, including weekends, were represented at least twice in the physical activity records. Age-adjusted correlation coefficients between like activities on the College Alumnus Questionnaire and physical activity records ranged from 0.25 to 0.65 in men and 0.28 to 0.86 in women. Correlations between the PAI-CAQ and validation criteria that reflected total and heavy-intensity physical activities were higher (r = 0.34-0.69, p < 0.05) than for lighter-intensity physical activities and motion detection expressed in MET-min.d-1 and kcal.d-1 (r < 0.35, p > 0.05). Test-retest reproducibility was higher over 1 month (r = 0.72) than over 8 and 9 months (r = 0.34 and 0.43) (p < 0.05). Energy expended in walking and stair climbing was underestimated on the College Alumnus Questionnaire, resulting in lower PAI-CAQ scores, as compared to the physical activity records.

Physical activity and risk of lung cancer.

BACKGROUND: Physical activity has been proposed to decrease lung cancer risk; however, few data are available. Further, no studies have examined specific kinds and intensities of activities. METHODS: We conducted a prospective cohort study among 13 905 male Harvard University alumni (mean age, 58.3 years), free of cancer. Men reported their walking, stair climbing and participation in sports or recreation on baseline questionnaires in 1977, and the occurrence of lung cancer on follow-up questionnaires in 1988 and 1993. Death certificates were obtained for decedents through 1992 to determine lung cancers not previously reported. RESULTS: During follow-up, 245 men developed lung cancer. Adjusting for age, cigarette smoking, and body mass index, the relative risks of lung cancer associated with <4200, 4200-8399, 8400-12 599 and > or =12 600 kJ/week of estimated energy expenditure at baseline were 1.00 (referent), 0.87 (95% CI: 0.64-1.18), 0.76 (95% CI: 0.52-1.11), and 0.61 (95% CI: 0.41-0.89), respectively; P trend = 0.0008. Similar trends were observed among non-smokers or former smokers in 1977 (82.7% of men) as well as among those who smoked >20 cigarettes a day in 1977 (8.0%), although the findings in the latter group were not statistically significant, possibly due to the small number. Walking, climbing stairs and participating in activities of at least moderate intensity (> or =4.5 MET, or multiples of resting metabolic rate) were each inversely associated with lung cancer risk, independent of the other activity components. However, light intensity activities (<4.5 MET) did not predict lung cancer risk. CONCLUSIONS: These data indicate that physical activity may be associated with lower risk of lung cancer among men. An energy expenditure of 12 600 kJ/week, achievable by perhaps 6-8 hours of at least moderate intensity physical activity, may significantly lower risk. Further studies are required to confirm these observations.

Alcohol consumption and risk of prostate cancer: The Harvard Alumni Health Study.

BACKGROUND: Although many studies suggest that consumption of alcohol increases the risk of several site-specific cancers, the evidence remains unclear for prostate cancer. Few data exist on beverage-specific associations as well as lifetime patterns of alcohol consumption and prostate cancer risk. METHODS: We prospectively followed 7612 Harvard alumni (mean age 66.6 years) from 1988 through 1993, during which 366 cases of incident prostate cancer occurred. Self-reported alcohol consumption was assessed at baseline from wine, beer, and liquor intake. Previous assessments during college and in 1977 were also available. RESULTS: Overall, the mean total alcohol consumption in 1988 was 123.1 g/week, of which 28.6% was from wine, 15.8% from beer, and 55.6% from liquor. Compared to men reporting almost never drinking alcohol in 1988, the multivariate relative risks (95% CI) for 1 drink/month to < 3 drinks/week, 3 drinks/week to < 1 drink/ day, 1 to < 3 drinks/day, and > or = 3 drinks/day were 1.33 (0.88-2.01), 1.65 (1.12-2.44), 1.85 (1.29-2.64), and 1.33 (0.86-2.05), respectively. Wine or beer consumption was unassociated with prostate cancer; however, moderate liquor consumption was associated with a significant 61-67% increased risk of prostate cancer (P, non-linear trend < 0.001). Men initiating alcohol consumption between 1977 and 1988 had a twofold increased risk of prostate cancer compared to men with almost no alcohol consumption at both times. CONCLUSIONS: In contrast to the majority of previous studies, we found a positive association between moderate alcohol consumption and the risk of prostate cancer. Liquor, but not wine or beer, consumption was positively associated with prostate cancer.

A history of physical activity, cardiovascular health and longevity: the scientific contributions of Jeremy N Morris, DSc, DPH, FRCP.

Since Hippocrates first advised us more than 2000 years ago that exercise-though not too much of it--was good for health, the epidemiology of physical activity has developed apace with the epidemiological method itself. It was only in the mid-20th century that Professor Jeremy N Morris and his associates used quantitative analyses, which dealt with possible selection and confounding biases, to show that vigorous exercise protects against coronary heart disease (CHD). They began by demonstrating an apparent protection against CHD enjoyed by active conductors compared with sedentary drivers of London double-decker buses. In addition, postmen seemed to be protected against CHD like conductors, as opposed to less active government workers. The Morris group pursued the matter further, adapting classical infectious disease epidemiology to the new problems of chronic, non-communicable diseases. Realizing that if physical exercise were to be shown to contribute to the prevention of CHD, it would have to be accomplished through study of leisure-time activities, presumably because of a lack of variability in intensities of physical work. Accordingly, they chose typical sedentary middle-management grade men for study, obtained 5-minute logs of their activities over a 2-day period, and followed them for non-fatal and fatal diseases. In a subsequent study, Morris et al. queried such executive-grade civil servants by detailed mail-back questionnaires on their health habits and health status. They then followed these men for chronic disease occurrence, as in the earlier survey. By 1973 they had distinguished between 'moderately vigorous' and 'vigorous' exercise. In both of these civil service surveys, they demonstrated strong associations between moderately vigorous or vigorous exercise and CHD occurrence, independent of other associations, in age classes 35-64 years. In the last 30 years, with modern-day computers, a large number of epidemiological studies have been conducted in both sexes, in different ethnic groups, in broad age classes, in a variety of social groups, and on most continents of the world. These studies have extended and amplified those of the Morris group, thereby helping to solidify the cause-and-effect evidence that exercise protects against heart disease and averts premature mortality.

Contributions of epidemiology to exercise science and cardiovascular health.

Much important information about the cardiovascular benefits and hazards of exercise requires the methods of epidemiology, i.e., the study in human populations of frequencies and distributions of disease in terms of time, place, and personal characteristics. The key techniques are comparison and contrast, but epidemiological analyses of physical activity and cardiovascular health often must rely on circumstantial evidence to assess cause-and-effect relationships. The study procedures must be designed to meet rigorous epidemiological principles: statistical association, temporal sequence, consistency, persistence, independence, dose-response relationship, specificity, alterability, repeatability, and confirmation of findings. Through measurement and contrast, study procedures aim to determine whether physically active persons experience a lower incidence of cardiovascular disease than do persons more sedentary. Based on these principles, current evidence indicates that exercise induces protective benefits against coronary heart disease that enable most persons to approach their potential longevity.

Physical activity and its relation to cancer risk: a prospective study of college alumni.

Previous investigations regarding the influence of physical activity on cancer risk generally have utilized a single assessment of activity, thus failing to account for changes over time. Additionally, one assessment may be somewhat imprecise. We attempted to overcome these problems in a study of 17,607 men (aged 30-79 yr), followed from 1962 or 1966 (1962/1966) through 1988. We assessed physical activity (based on self-reported stair climbing, walking and participation in sports or recreational activities) twice: in 1962/1966 and again in 1977. A total of 280 colon, 53 rectal, 454 prostatic, 262 lung, and 88 pancreatic cancers developed during follow-up. Among alumni with Quetelet's index > or = 26 units, those highly active (energy expenditure > or = 2,500 kcal [> or = 10,460 kJ].wk-1) had 0.19 (95% confidence interval, 0.02-1.52) to 0.56 (0.29-1.09) times the colon cancer risk of those inactive (< 1,000 kcal [< 4,184 kJ].wk-1). Colon cancer risk was unrelated to level of activity among alumni with Quetelet's index < 26 units. Highly active alumni also had 0.39 (95% confidence interval, 0.18-0.85) to 0.62 (0.45-0.85) times the lung cancer risks of their inactive colleagues. Physical activity was not significantly associated with risks of rectal, prostatic, or pancreatic cancers. The biologic basis for a protective effect of increased activity on cancer risk appears plausible.