Dairy products and pancreatic cancer risk: a pooled analysis of 14 cohort studies.

Pancreatic cancer has few early symptoms, is usually diagnosed at late stages, and has a high case-fatality rate. Identifying modifiable risk factors is crucial to reducing pancreatic cancer morbidity and mortality. Prior studies have suggested that specific foods and nutrients, such as dairy products and constituents, may play a role in pancreatic carcinogenesis. In this pooled analysis of the primary data from 14 prospective cohort studies, 2212 incident pancreatic cancer cases were identified during follow-up among 862 680 individuals. Adjusting for smoking habits, personal history of diabetes, alcohol intake, body mass index (BMI), and energy intake, multivariable study-specific hazard ratios (MVHR) and 95% confidence intervals (CIs) were calculated using the Cox proportional hazards models and then pooled using a random effects model. There was no association between total milk intake and pancreatic cancer risk (MVHR = 0.98, 95% CI = 0.82-1.18 comparing ≥500 with 1-69.9 g/day). Similarly, intakes of low-fat milk, whole milk, cheese, cottage cheese, yogurt, and ice-cream were not associated with pancreatic cancer risk. No statistically significant association was observed between dietary (MVHR = 0.96, 95% CI = 0.77-1.19) and total calcium (MVHR = 0.89, 95% CI = 0.71-1.12) intake and pancreatic cancer risk overall when comparing intakes ≥1300 with <500 mg/day. In addition, null associations were observed for dietary and total vitamin D intake and pancreatic cancer risk. Findings were consistent within sex, smoking status, and BMI strata or when the case definition was limited to pancreatic adenocarcinoma. Overall, these findings do not support the hypothesis that consumption of dairy foods, calcium, or vitamin D during adulthood is associated with pancreatic cancer risk.

Long-term and baseline recreational physical activity and risk of endometrial cancer: the California Teachers Study.

BACKGROUND: Physical activity may be associated with decreasing endometrial cancer risk; it remains unclear whether the association is modified by body size. METHODS: Among 93 888 eligible California Teachers Study participants, 976 were diagnosed with incident endometrial cancer between 1995-1996 and 2007. Cox proportional hazards regression methods were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for endometrial cancer associated with long-term (high school through age 54 years) and baseline (3 years prior to joining the cohort) strenuous and moderate recreational physical activity, overall and by body size. RESULTS: Increased baseline strenuous recreational physical activity was associated with decreased endometrial cancer risk (Ptrend=0.006) with approximately 25% lower risk among women exercising >3 h per week per year than among those exercising <1/2 h per week per year (RR, 0.76; 95% CI, 0.63-0.92). This inverse association was observed among overweight/obese women (body mass index ≥25 kg m(-2); Ptrend=0.006), but not among thinner women (Ptrend=0.12). Baseline moderate activity was associated with lower risk among overweight/obese women. CONCLUSION: Increasing physical activity, particularly strenuous activity, may be a lifestyle change that overweight and obese women can implement to reduce their endometrial cancer risk.

The etiology of uterine sarcomas: a pooled analysis of the epidemiology of endometrial cancer consortium.

BACKGROUND: Uterine sarcomas are characterised by early age at diagnosis, poor prognosis, and higher incidence among Black compared with White women, but their aetiology is poorly understood. Therefore, we performed a pooled analysis of data collected in the Epidemiology of Endometrial Cancer Consortium. We also examined risk factor associations for malignant mixed mullerian tumours (MMMTs) and endometrioid endometrial carcinomas (EECs) for comparison purposes. METHODS: We pooled data on 229 uterine sarcomas, 244 MMMTs, 7623 EEC cases, and 28,829 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) for risk factors associated with uterine sarcoma, MMMT, and EEC were estimated with polytomous logistic regression. We also examined associations between epidemiological factors and histological subtypes of uterine sarcoma. RESULTS: Significant risk factors for uterine sarcoma included obesity (body mass index (BMI)≥30 vs BMI<25 kg m(-2) (OR: 1.73, 95% CI: 1.22-2.46), P-trend=0.008) and history of diabetes (OR: 2.33, 95% CI: 1.41-3.83). Older age at menarche was inversely associated with uterine sarcoma risk (≥15 years vs <11 years (OR: 0.70, 95% CI: 0.34-1.44), P-trend: 0.04). BMI was significantly, but less strongly related to uterine sarcomas compared with EECs (OR: 3.03, 95% CI: 2.82-3.26) or MMMTs (OR: 2.25, 95% CI: 1.60-3.15, P-heterogeneity=0.01). CONCLUSION: In the largest aetiological study of uterine sarcomas, associations between menstrual, hormonal, and anthropometric risk factors and uterine sarcoma were similar to those identified for EEC. Further exploration of factors that might explain patterns of age- and race-specific incidence rates for uterine sarcoma are needed.

Obesity, waist size and prevalence of current asthma in the California Teachers Study cohort.

BACKGROUND: Obesity is a risk factor for asthma, particularly in women, but few cohort studies have evaluated abdominal obesity which reflects metabolic differences in visceral fat known to influence systemic inflammation. A study was undertaken to examine the relationship between the prevalence of asthma and measures of abdominal obesity and adult weight gain in addition to body mass index (BMI) in a large cohort of female teachers. METHODS: Prevalence odds ratios (ORs) for current asthma were calculated using multivariable linear modelling, adjusting for age, smoking and race/ethnicity. RESULTS: Of the 88 304 women in the analyses, 13% (n = 11,500) were obese (BMI > or = 30 kg/m(2)) at baseline; 1334 were extremely obese (BMI > or = 40 kg/m(2)). Compared with those of normal weight, the adjusted OR for adult-onset asthma increased from 1.40 (95% confidence interval (CI) 1.31 to 1.49) for overweight women to 3.30 (95% CI 2.85 to 3.82) for extremely obese women. Large waist circumference (>88 cm) was associated with increased asthma prevalence, even among women with a normal BMI (OR 1.37, 95% CI 1.18 to 1.59). Among obese women the OR for asthma was greater in those who were also abdominally obese than in women whose waist was < or = 88 cm (2.36 vs 1.57). Obese and overweight women were at greater risk of severe asthma episodes, measured by urgent medical visits and hospital admissions. CONCLUSIONS: This study confirms the association between excess weight and asthma severity and prevalence, and showed that a large waist was associated with increased asthma prevalence even among women considered to have normal body weight.

Relative weight, weight change, height, and breast cancer risk in Asian-American women.

BACKGROUND: Breast cancer incidence rates have historically been four to seven times higher in the United States than in China or Japan, although the reasons remain elusive. When Chinese, Japanese, or Filipino women migrate to the United States, their breast cancer risk rises over several generations and reaches that for white women in the United States, indicating that modifiable exposures are involved. In a previous report on this case-control study of breast cancer in Asian-American women, designed to take advantage of their diversity in risk and lifestyle, we demonstrated a sixfold gradient in risk by migration history, comparable to the international differences in breast cancer incidence rates. PURPOSE: In this analysis, we have examined the roles of adult height, adiposity, and weight change in breast cancer etiology. METHODS: A population-based, case-control study of breast cancer was conducted among women of Chinese, Japanese, and Filipino ethnicities, aged 20-55 years, living in San Francisco-Oakland (CA), Los Angeles (CA), and Oahu (HI) during the period from April 1, 1983, through June 30, 1987. We successfully interviewed 597 (70%) of 852 eligible case subjects and 966 (75%) of 1287 eligible control subjects from August 1985 through February 1989. Subjects were asked about current height, usual adult weight, and usual weight in each decade of life, excluding the most recent 3 years and any periods of pregnancy. RESULTS: Height, recent adiposity (weight in the current decade of life/height 1.5), and recent weight change (between the current and preceding decades of life) were strong predictors of breast cancer risk after adjustment was made for accepted breast cancer risk factors. Risk doubled (relative risk [RR] = 2.01; 95% confidence interval [CI] = 1.16-3.49) over the 7-inch (17.8-cm) range in height (two-sided P for trend = .003), with comparable effects in both premenopausal and postmenopausal women. Except for reduced risk in the heavy, younger women (weight/height 1.5 > 29 kg/m 1.5 and < 40 years old), risk was positively associated with usual adult adiposity. Trends in risk became more striking as adiposity in each succeeding decade of adult life was considered. Women in their 50s and in the top quintile for their age group had twice the breast cancer risk (RR = 2.13; 95% CI = 1.17-3.87) of women in the bottom quintile (two-sided P for trend = .004). Women in their 50s, above the median adiposity for their age group, and with a recent gain of more than 10 pounds had three times the risk (RR = 3.01; 95% CI = 1.45-6.25) of women below the median adiposity and with no recent weight change. Recent weight loss was consistently associated with reduced risk (RRs of approximately 0.7) relative to no recent weight change. CONCLUSIONS: Adult adiposity, weight change, and height are critical determinants of breast cancer risk. Increased adiposity and weight gain in the decade preceding diagnosis are especially influential, suggesting that excess weight may function as a late stage promoter. IMPLICATIONS: Weight maintenance and/or reduction as an adult, possibly accompanied by specific changes in diet and physical activity, may have a significant and rapid impact on breast cancer risk.

Migration patterns and breast cancer risk in Asian-American women.

BACKGROUND: Breast cancer incidence rates have historically been 4-7 times higher in the United States than in China or Japan, although the reasons remain elusive. When Chinese, Japanese, or Filipino women migrate to the United States, breast cancer risk rises over several generations and approaches that among U.S. Whites. PURPOSE: Our objective was to quantify breast cancer risks associated with the various migration patterns of Asian-American women. METHODS: A population-based, case-control study of breast cancer among women of Chinese, Japanese, and Filipino ethnicities, aged 20-55 years, was conducted during 1983-1987 in San Francisco-Oakland, California, Los Angeles, California, and Oahu, Hawaii. We successfully interviewed 597 case subjects (70% of those eligible) and 966 control subjects (75%). RESULTS: A sixfold gradient in breast cancer risk by migration patterns was observed. Asian-American women born in the West had a breast cancer risk 60% higher than Asian-American women born in the East. Among those born in the West, risk was determined by whether their grandparents, especially grandmothers, were born in the East or the West. Asian-American women with three or four grandparents born in the West had a risk 50% higher than those with all grandparents born in the East. Among the Asian-American women born in the East, breast cancer risk was determined by whether their communities prior to migration were rural or urban and by the number of years subsequently lived in the West. Migrants from urban areas had a risk 30% higher than migrants from rural areas. Migrants who had lived in the West for a decade or longer had a risk 80% higher than more recent migrants. Risk was unrelated to age at migration for women migrating at ages less than 36 years. Ethnic-specific incidence rates of breast cancer in the migrating generation were clearly elevated above those in the countries of origin, while rates in Asian-Americans born in the West approximated the U.S. White rate. CONCLUSIONS: Exposure to Western lifestyles had a substantial impact on breast cancer risk in Asian migrants to the United States during their lifetime. There was no direct evidence of an especially susceptible period, during either menarche or early reproductive life. IMPLICATIONS: Because heterogeneity in breast cancer risk in these ethnic populations is similar to that in international comparisons and because analytic epidemiologic studies offer the opportunity to disentangle correlated exposures, this study should provide new insights into the etiology of breast cancer.

Soy intake and risk of breast cancer in Asians and Asian Americans.

Evidence from case-control studies suggests, although not entirely consistently, that soy intake may protect against breast cancer. The designs and findings of studies conducted in Asian women living in Japan, Singapore, China, and the United States are reviewed. Because of the considerably higher intake of soy by native Asians than by Asian Americans living in California and Hawaii, these studies investigated different segments of the dose-response relation between soy intake and breast cancer risk. Data are not sufficient to determine the amount or frequency of soy intake effective in protecting against breast cancer. Of concern is that soy intake may be homogeneously high in Asia, making it difficult to identify differences in breast cancer risk between high and moderate daily consumers. In studies conducted in Asian Americans, it is difficult to be certain that soy intake is not a marker of other factors related to Western lifestyle that are causally associated with risk of breast cancer. Additional studies assessing the role of soy and breast cancer are needed. These studies should assess intake of all food sources of soy, considering portion size as well as other dietary and nondietary factors that may confound the soy-breast cancer association. A better understanding of the mechanisms whereby soy intake may influence the risk of breast cancer is also needed. Dietary intervention studies with soy will provide information on the acute effects of soy on endogenous hormone concentrations. Cross-sectional and longitudinal studies are necessary to investigate the longer-term relations between hormone concentrations and soy intake in women.

Urinary phytoestrogen levels in young women from a multiethnic population.

Phytoestrogens include several classes of chemical compounds (i.e., isoflavones, coumestans, and lignans) which are structurally similar to endogenous estrogens. In biological systems, they have both estrogenic and antiestrogenic effects and may reduce the risk of developing certain types of hormonally related diseases. However, little information is available on population differences in exposure to phytoestrogens. To examine racial/ethnic differences in urinary phytoestrogen levels, 50 young women (ages 20-40 years) were randomly selected from participants in a previous epidemiological study in which 24-h urine specimens and a dietary assessment were obtained. Subjects were members of the Kaiser Permanente Medical Care Program of northern California. Selection was stratified on race/ethnicity. Urinary levels of seven phytoestrogens were measured using high-performance liquid chromatography-mass spectrometry. Substantial variation in phytoestrogen levels was observed and racial/ethnic differences are described. The highest levels of coumestrol and the lignans were observed in white women and the lowest levels in Latina and African American women. Genistein levels, however, were highest in Latina women; other isoflavone levels did not differ significantly by race/ethnicity.

Tofu and risk of breast cancer in Asian-Americans.

Breast cancer rates among Asian-Americans are lower than those of US whites but considerably higher than rates prevailing in Asia. It is suspected that migration to the US brings about a change in endocrine function among Asian women, although reasons for this change remain obscure. The high intake of soy in Asia and its reduced intake among Asian-Americans has been suggested to partly explain the increase of breast cancer rates in Asian-Americans. We conducted a population-based case-control study of breast cancer among Chinese-, Japanese-, and Filipino-American women in Los Angeles County MSA, San Francisco Oakland MSA, and Oahu, Hawaii. Using a common questionnaire which assessed frequency of intake of some 90 food items, 597 Asian-American women (70% of those eligible) diagnosed with incident, primary breast cancer during 1983-1987 and 966 population-based controls (75% of those eligible) were interviewed. Controls were matched to cases on age, ethnicity, and area of residence. This analysis compares usual adult intake of soy (estimated primarily from tofu intake) among breast cancer cases and control women. After adjustment for age, ethnicity and study area, intake of tofu was more than twice as high among Asian-American women born in Asia (62 times per year) compared to those born in the US (30 times per year). Among migrants, intake of tofu decreased with years of residence in the US. Risk of breast cancer decreased with increasing frequency of intake of tofu after adjustment for age, study area, ethnicity, and migration history; the adjusted OR associated with each additional serving per week was 0.85 (95% CI = 0.74-0.99). The protective effect of high tofu intake was observed in pre- and postmenopausal women. This association remained after adjustment for selected dietary factors and menstrual and reproductive factors. However, this study was not designed specifically to investigate the role of soy intake and our assessment of soy intake may be incomplete. We cannot discount the possibility that soy intake is a marker of other protective aspects of Asian diet and/or Asian lifestyle.

Iodine and thyroid cancer risk among women in a multiethnic population: the Bay Area Thyroid Cancer Study.

Research on the relationship between iodine exposure and thyroid cancer risk is limited, and the findings are inconclusive. In most studies, fish/shellfish consumption has been used as a proxy measure of iodine exposure. The present study extends this research by quantifying dietary iodine exposure as well as incorporating a biomarker of long-term (1 year) exposure, i.e., from toenail clippings. This study is conducted in a multiethnic population with a wide variation in thyroid cancer incidence rates and substantial diversity in exposure. Women, ages 20-74, residing in the San Francisco Bay Area and diagnosed with thyroid cancer between 1995 and 1998 (1992-1998 for Asian women) were compared with women selected from the general population via random digit dialing. Interviews were conducted in six languages with 608 cases and 558 controls. The established risk factors for thyroid cancer were found to increase risk in this population: radiation to the head/neck [odds ratio (OR), 2.3; 95% confidence interval (CI), 0.97-5.5]; history of goiter/nodules (OR, 3.7; 95% CI, 2.5-5.6); and a family history of proliferative thyroid disease (OR, 2.5; 95% CI, 1.6-3.8). Contrary to our hypothesis, increased dietary iodine, most likely related to the use of multivitamin pills, was associated with a reduced risk of papillary thyroid cancer. This risk reduction was observed in "low-risk" women (i.e., women without any of the three established risk factors noted above; OR, 0.53; 95% CI, 0.33-0.85) but not in "high-risk" women, among whom a slight elevation in risk was seen (OR, 1.4; 95% CI, 0.56-3.4). However, no association with risk was observed in either group when the biomarker of exposure was evaluated. In addition, no ethnic differences in risk were observed. The authors conclude that iodine exposure appears to have, at most, a weak effect on the risk of papillary thyroid cancer.

Predictors of misclassification of Hispanic ethnicity in a population-based cancer registry.

PURPOSE: Hispanic ethnicity is often used as a category for calculating population-based rates or assessing risk of epidemiologic studies. However, ethnic misclassification can lead to false conclusions unless the extent of misclassification and the characteristics of those misclassified are understood. METHODS: This study explored determinants of ethnic misclassification in a sample of 1154 cancer cases in the San Francisco-Oakland cancer registry, where ethnic classification is based on surname or medical record report. We compared the following: correctly classified Hispanics, persons classified as Hispanic who self-identified as non-Hispanic, and persons classified as non-Hispanic who self-identified as Hispanic. RESULTS: Among men classified as Hispanic, those most likely to self-identify as non-Hispanic did not speak Spanish, had non-Spanish surnames, and were recent immigrants. Women misclassified as Hispanic did not speak Spanish or have Spanish maiden names, nor did they have mothers with Spanish maiden names. Persons who called themselves Hispanic, but were misclassified by the registry, were likely to be non-Spanish speaking college-education males. CONCLUSIONS: Researchers using ethnicity should be aware of how ethnicity was determined and how this classification may bias or confound their results.

Recent trends in the incidence of salivary gland cancer.

Beginning in 1985, a sudden and sustained doubling of salivary gland cancer incidence, among men only, is observed in the San Francisco-Oakland Metropolitan Statistical Area. Registry data are examined to determine the nature of this increase and its possible association with the AIDS epidemic. Changes in patient characteristics are assessed by comparing their distribution among recently diagnosed cases (1985-1988) to an expectation based on population growth and the age-specific incidence among patients diagnosed earlier (1973-1984). Based on the observed patterns, it is unlikely that the temporal increase in these tumours is a direct result of the AIDS epidemic or solely the result of a shift in the prevalence of established risk factors. The increase is predominantly seen in men over the age of 75 at diagnosis (O/E = 2.3, p = 0.02) and is observed among both those with and without a prior cancer (O/E = 2.7, p = 0.02 and O/E = 1.5, p = 0.06, respectively). Radiation for the prior cancer was not associated with increased occurrence. Military exposure is crudely approximated by examining birth cohorts. However, the cohort data do not support a hypothesis of military exposure.

Phytoestrogens, body composition, and breast cancer.

To the extent that diet is involved in the etiology of breast cancer, its effect may be mediated, in part, through hormonal mechanisms. It has been suggested that the consumption of phytoestrogens is related inversely to breast cancer risk. Phytoestrogens are weak estrogens of plant derivation that may have antiestrogenic effects through competitively binding to estrogen receptors, thus diminishing the binding of stronger endogenous estrogens. This paper advances the hypothesis that, through this mechanism, dietary phytoestrogens may attenuate the adverse consequences of obesity on the development of postmenopausal breast cancer. Such an association might partly explain the low breast cancer rates observed among postmenopausal Hispanic women despite their greater adiposity, an important breast cancer risk factor. This hypothesis would lead us to expect that obesity increases the risk of postmenopausal breast cancer in women consuming small quantities of phytoestrogens but does not increase risk in women consuming larger quantities. If the hypothesis is confirmed, such as association could have important implications for reducing breast cancer risk through diet, using naturally occurring substances, particularly in women for whom postmenopausal obesity is an important health concern.

Breast cancer: magnitude of the problem and descriptive epidemiology.

Breast cancer is the most common cancer among women in the United States. Knowledge of the descriptive epidemiology of breast cancer is useful both in suggesting etiologic hypotheses and, if preventive measures can be identified, in delineating high-risk groups to be targeted for preventive efforts. Demographic risk factors include increasing age (in Western countries), being white for breast cancer diagnosed at age 45 years or more, being black for breast cancer diagnosed at less than 40 years of age, high socioeconomic status, having never married, being of the Jewish faith, urban residence, and residence in the northern (as compared with the southern) United States. Incidence rates are generally highest in North American and Northern European countries, intermediate in Southern and Eastern European and South American countries, and lowest in Asia and Africa. The most notable characteristic of the descriptive epidemiology of breast cancer in recent years is perhaps the rapidly increasing incidence rates in developing countries. Identification of specific reasons for these increasing rates would contribute substantially to our understanding of the epidemiology of breast cancer.

Environmental factors and the risk of salivary gland cancer.

Cancer of the major salivary glands is rare, and little is known about its etiology. We conducted a population-based case-control study to elucidate the risk factors for these tumors. Of 199 cases diagnosed with salivary gland tumors between 1989 and 1993, 150 (75%) were interviewed. We subsequently excluded nine cases based on review of pathology specimens. We identified 271 controls through random-digit dialing and the Health Care Finance Administration files; 191 (70%) were interviewed. Therapeutic medical radiation treatment to the head or neck [odds ratio (OR) = 2.6; 95% confidence interval (CI) = 0.84-8.1], full mouth dental x-rays (OR = 1.6; 95% CI = 1.0-2.7), and ultraviolet light treatment to the head or neck (OR = 1.9; 95% CI = 0.89-4.3) were associated with increased risk. These elevations in risk were largely limited to those exposed before 1955, when the exposure dose was substantially higher. Occupational exposure to radiation/radioactive materials (OR = 2.4; 95% CI = 1.0-5.4) and nickel compounds/alloys (OR = 6.0; 95% CI = 1.6-22.0), as well as employment in the rubber industry (OR = 7.0; 95% CI = 0.80-60.3), increased risk. In men, current smoking (OR = 2.1; 95% CI = 0.98-4.7) and heavy alcohol consumption (OR = 2.5; 95% CI = 1.1-5.7) were associated with risk, but these factors were not strongly related to salivary gland cancer in women.

Diet and the risk of salivary gland cancer.

Cancer of the major salivary glands is relatively rare, and little is known about its etiology. The only established risk factors are radiation exposure and a prior cancer. The role of diet in the development of salivary gland tumors has not been addressed previously. The results from a population-based case-control study conducted in the greater San Francisco-Monterey Bay area examining the association between dietary intake and salivary gland cancer risk are presented. Of 199 cases diagnosed with salivary gland tumors between 1989 and 1993, 150 (75%) were interviewed. Nine cases were subsequently excluded based on review of pathology specimens. Of 271 controls identified through random-digit dialing and the Health Care Finance Administration files, 191 (70%) were interviewed. Eight cases and seven controls who over- or underreported dietary intake were excluded from analysis. Vitamin C intake of > 200 mg/day compared with < or = 100 mg/day was associated with a 60% decrease in salivary gland cancer risk (odds ratio (OR) = 0.40, 95% confidence interval (CI) 0.22-0.70). Inverse associations observed for carotene, vitamin E, and fiber from fruits and vegetables were diminished when adjusted for vitamin C intake. Fiber from been sources was associated with a 51% decrease in risk after adjusting for vitamin C intake (OR = 0.49, 95% CI 0.26-0.92 for > 1.4 g/day compared with < or = 0.4 g/day). Cholesterol intake was associated with elevated risk (OR = 1.67, 95% CI 1.2-2.4 for a 10% increase in calories from cholesterol). These findings suggest that preventive strategies developed for common chronic diseases, such as increased consumption of fruits and vegetables and limiting foods high in cholesterol, also may be effective in preventing these rare tumors.

Menstrual and reproductive factors for salivary gland cancer risk in women.

Several observations suggest that salivary gland cancer may be, in part, a hormonally dependent disease. We examined associations between hormonally mediated life events and salivary gland cancer risk in a population-based case-control study. Of 76 women diagnosed between 1989 and 1993, 63 (83%) were interviewed. Of 111 population controls, 83 (75%) were interviewed. Early menarche (OR = 4.1, 95% CI = 1.4-12.1) and nulliparity (OR = 2.6, 95% CI = 1.0-6.7) were associated with increased risk whereas late age at first full-term pregnancy (OR = 0.19, 95% CI = 0.3-1.2) and longer duration of oral contraceptive use (OR = 0.31, 95% CI = 0.10-1.0) were associated with diminished risk. These findings are consistent with a hormonal component in salivary gland cancer risk.

Temporal trends in the incidence of cutaneous malignant melanoma among Caucasians in the San Francisco-Oakland MSA.

Temporal changes in the incidence of cutaneous malignant melanoma (CMM) were examined in the San Francisco-Oakland (California, United States) Metropolitan Statistical Area (MSA) between 1976 and 1987, using data from the population-based cancer registry. This analysis was conducted after the completion of a project designed to eliminate bias in the reporting of CMM due to changes in medical practice. The incidence of CMM is higher in the San Francisco-Oakland MSA than nationally. From 1976 through 1987, the incidence of invasive CMM increased from 9.8 +/- 0.9 to 16.5 +/- 1.1 per 100,000 (P = 0.0001) among men and from 9.3 +/- 0.8 to 12.7 +/- 0.9 per 100,000 (P = 0.001) among women. Age-specific, histologic-specific, and anatomic site-specific trends were also evaluated. The temporal patterns of CMM suggest that the recent increases are not accounted for solely by ascertainment bias due to reporting practices. The observed trends are consistent with early detection efforts and with changes in the prevalence of risk factors.

Characteristics relating to ovarian cancer risk: collaborative analysis of 12 U.S. case-control studies. VI. Nonepithelial cancers among adults. Collaborative Ovarian Cancer Group.

Nonepithelial ovarian cancers are rare, and little is known about their etiology. Of particular interest are the effects of oral contraceptive use and pregnancy, both of which are associated with large decreases in risk for epithelial ovarian cancer. We examined the risk factors for nonepithelial ovarian tumors by combining data from four case-control studies conducted in the United States. We compared personal characteristics of 38 germ cell cases and 45 stromal cases, respectively, with 1,142 and 2,617 general population controls. All subjects were over age 18 years. For germ cell tumors, there was a weak negative association with parity but no consistent pattern of decreasing risk with increasing parity. In contrast, relative to nulligravid women, gravid nulliparous women were at increased risk of developing a germ cell cancer [odds ratio (OR) = 4.8, 95% confidence interval (CI) = 1.2-18.6]. The use of oral contraceptives was also associated with elevated risk (OR = 2.0, 95% CI = 0.77-5.1); however, no clear trends in risk were observed. For stromal tumors, oral contraceptive use was associated with decreased risk (OR = 0.37, 95% CI = 0.16-0.83), whereas pregnancy was associated with a small elevation in risk. A trend of increasing risk with increasing age at first term pregnancy was observed, with an odds ratio of 3.6 (95% CI = 1.0-12.5) for a first birth after age 29 years. Risk factors for nonepithelial ovarian cancers do not appear to parallel each other or those for epithelial ovarian cancer.

Sources of phytoestrogen exposure among non-Asian women in California, USA.

OBJECTIVE: We recently described the development of a comprehensive database for assessing phytoestrogen exposure in epidemiologic studies. This paper describes the first application of this database and the primary sources of phytoestrogen consumption in non-Asian women. METHODS: Four hundred and forty-seven randomly selected African-American, Latina, and white women, ages 50-79 years, residing in California's San Francisco Bay Area and participating as controls in an ongoing population-based case-control study of breast cancer, were included in the present analysis. Average daily consumption of each of seven phytoestrogenic compounds was determined for each woman by combining the values from the new database with food consumption reported on a food-frequency questionnaire. RESULTS: Phytoestrogens in the non-Asian Bay Area diet appear to come primarily from: (1) traditional soy-based foods (e.g. tofu and soy milk); (2) "hidden" sources of soy (e.g. foods containing added soy protein isolate, soy concentrate, or soy flour, e.g. many brands of doughnuts and white bread); and (3) a variety of foods which contain only low to moderate amounts of phytoestrogens per 100 grams but which are frequently consumed (e.g. coffee and orange juice). CONCLUSIONS: In the absence of a comprehensive assessment of various phytoestrogens in a wide variety of foods, epidemiologic studies could suffer from the effects of uncontrolled confounding by unmeasured sources of phytoestrogen exposure potentially leading to biased estimates of effect and misinterpretation of findings.