Alcohol consumption and colon and rectal cancer in postmenopausal women

The associations between alcohol and colon and rectal cancers were examined in the Iowa Women's Health Study. In January 1986, 41 837 postmenopausal women, aged 55-69, completed a questionnaire including usual alcohol intake and other information. Through December 1990, 237 incident colon and 75 rectal cancer cases occurred. Mantel-Haenszel age-adjusted relative risks (RR) and 95% confidence intervals (CI) for consumers of < 4.0 and > or = 4.0 g of alcohol per day compared to abstainers were 1.07 (0.61-1.89) and 1.27 (0.72-2.24) (P for trend = 0.46) for rectal cancer. Alcohol intake was inversely associated with distal colon cancer (RR for < 4.0 and > or = 4.0 g of alcohol per day were 0.64 and 0.69 respectively, P for trend = 0.04), which was specific to wine; however, no association was observed with proximal colon cancer (P for trend = 0.94). This is the only report of an inverse association between alcohol and colon cancer in women. Because gut physiology and alcohol metabolism differ between men and women, more research on the association between alcohol and colon cancer in women only, is warranted.

Does body fat distribution promote familial aggregation of adult onset diabetes mellitus and postmenopausal breast cancer?

Noninsulin-dependent diabetes mellitus and postmenopausal breast cancer share a number of risk factors, including obesity, increased waist-to-hip ratio, and a positive family history. If risk for these diseases is mediated through a familial tendency for abdominal obesity, then one might expect to see familial clustering of both diseases. We analyzed data from a prospective cohort study of 41,837 Iowa women age 55-69 years. Diabetes was not associated with incidence of breast cancer [relative risk (RR) = 0.97]. The association between family history of breast cancer and breast cancer incidence, however, was slightly modified by individual history of diabetes: a positive family history of breast cancer in the absence of baseline diabetes was associated with a relative risk of 1.36 [95% confidence interval (CI) = 1.08-1.70], whereas the presence of both factors was associated with a RR of 1.87 (95% CI = 0.93-3.76). Adjustment for waist-to-hip ratio greatly diminished this difference. Conversely, a family history of breast cancer was associated with a RR of 5-year diabetes mortality of 1.94 (95% CI = 1.17-3.24) that persisted after stratification by tertile of waist-to-hip ratio. No clear association of family history of breast cancer and waist-to-hip ratio for self-reported diabetes incidence was evident. These data are indicative of a complex interrelation between waist-to-hip ratio, familial predisposition, diabetes, and breast cancer.

Evidence for the formation of multiple types of acetaldehyde-haemoglobin adducts

Acetaldehyde readily reacted with red blood cells and isolated haemoglobin to form adducts. We examined acetaldehyde-haemoglobin reaction products, isolated from red blood cells incubated with acetaldehyde (AcH), for the presence of stable peptide-specific acetaldehyde adducts. Red blood cell incubations were with 20, 50, and 200 mM acetaldehyde for 3, 24 and 48 hr. Peptide-specific [14C]acetaldehyde modifications of Hb from each incubation were identified by tryptic peptide mapping procedures. Nine peptides had modifications and six were found in incubations with 20 mM acetaldehyde. Two of the peptides were acetaldehyde modifications of the Hb alpha- and beta-chain N-termini. Stability studies indicated that the remaining seven [14C]AcH-modified peptides did not result, as can occur under certain conditions, from the transfer of AcH on the N-termini of Hb to N-termini formed after trypsin digestion. An analysis of the relative amounts of [14C]AcH-peptide adducts indicated that at least two of the seven peptides had reactivities for AcH different than the N-termini of Hb; that is, at least two modified peptides differ from imidazolidine-type adducts formed on the N-termini. The presence of multiple modifications with different sensitivities for AcH adduct formation may be useful in developing markers of alcohol consumption.

Vegetables, fruit, and colon cancer in the Iowa Women's Health Study

Previous epidemiologic studies have shown an inverse association between vegetable and fruit consumption and colon cancer risk; few of these studies have been prospective or have focused on women. This report describes results from a prospective cohort study of 41,837 women aged 55-69 years who completed a 127-item food frequency questionnaire in 1986 and were monitored for cancer incidence for 5 years via the State Health Registry of Iowa. After specific exclusion criteria were applied, 212 colon cancer cases and 167,447 person-years were available for analysis. Intakes of 15 vegetable and fruit groups and dietary fiber were the major factors of interest. Consumption of garlic was inversely associated with risk, with an age- and energy-adjusted relative risk of 0.68 (95% confidence interval (CI) 0.46-1.02) for the uppermost versus the lowermost consumption levels. Inverse associations were also observed for intakes of all vegetables and dietary fiber; age- and energy-adjusted relative risks for the uppermost versus the lowermost intake quartiles were 0.73 (95% CI 0.47-1.13) and 0.80 (95% CI 0.49-1.31), respectively. Associations for the other vegetable and fruit groups were less remarkable.

Sugar, meat, and fat intake, and non-dietary risk factors for colon cancer incidence in Iowa women (United States)

To investigate the relation of dietary intakes of sucrose, meat, and fat, and anthropometric, lifestyle, hormonal, and reproductive factors to colon cancer incidence, data were analyzed from a prospective cohort study of 35,215 Iowa (United States) women, aged 55-69 years and without a history of cancer, who completed mailed dietary and other questionnaires in 1986. Through 1990, 212 incident cases of colon cancer were documented. Proportional hazards regression was used to adjust for age and other risk factors. Risk factors found to be associated significantly with colon cancer included: (i) sucrose-containing foods and beverages other than ice cream/milk; relative risks (RR) across the quintiles = 1.00, 1.73, 1.56, 1.54, and 2.00 (95% confidence intervals [CI] for quintiles two and five exclude 1.0); (ii) sucrose; RR across the quintiles = 1.00, 1.70, 1.81, 1.82, and 1.45 (CI for quintiles two through four exclude 1.0); (iii) height; RR = 1.23 for highest to lowest quintile (P for trend = 0.02); (iv) body mass index; RR = 1.41 for highest to lowest quintile (P for trend = 0.03); and (v) number of livebirths, RR = 1.59 for having had one to two livebirths and 1.80 for having had three or more livebirths compared with having had none (P for trend = 0.04). These data support hypotheses that sucrose intake or being tall or obese increases colon cancer risk; run contrary to the hypothesis that increased parity decreases risk; support previous findings of no association with demographic factors other than age, cigarette smoking, or use of oral contraceptives or estrogen replacement therapy; and raise questions regarding previous associations with meat, fat, protein, and physical activity.

Determination of the Ca2+ and Mg2+ affinity constants of troponin C from eel skeletal muscle and positioning of the single tryptophan in the primary structure

The complete amino acid sequence of troponin C (ETnC) from the white muscle of the European eel has been determined by Edman degradation procedures. Its single tryptophan residue is situated in helix H at amino acid position 152 of the aligned sequence; the tryptophan is the first residue on the C-terminal side of Ca2+ binding loop IV. The increase of tryptophan fluorescence emission intensity occurring upon titration of ETnC with Ca2+ has been used to determine the affinity constants of ETnC for Ca2+. The calculated affinity of ETnC for Ca2+ results in a K(Ca) of 1.3 10(7) M-1, typical of the Ca(2+)-Mg2+ sites of the second domain of fast skeletal muscle TnCs. Moreover, a direct competition between Ca2+ and Mg2+ was also observed. The calculated affinity of ETnC for Mg2+ is K(Mg) = 1.2 10(3) M-1. In order to probe the affinity constants of the Ca2+ binding sites of the regulatory domain, ETnC was labelled with dansylaziridine (Danz). The Danz fluorescent signal was used to estimate the affinity constants of ETnC-Danz for Ca2+ and also for Mg2+ (assuming a competitive behaviour between these two metal ions). The calculated affinity constants are K(Ca) = 9.4 10(5) M-1 and K(Mg) = 2.0 10(2) M-1, respectively. These values are typical of the Ca(2+)-specific sites of the regulatory domain of fast skeletal muscle TnCs.

Association of body fat distribution and family histories of breast and ovarian cancer with risk of postmenopausal breast cancer

The authors recently published data from a prospective cohort study of postmenopausal women (N Engl J Med 1992;326:1323-9) which suggested that a high waist/hip ratio was associated with a significantly increased risk of breast cancer in women with a positive family history of breast cancer. Since families with aggregations of breast and ovarian cancer demonstrate more consistent genetic linkage to markers on chromosome 17q than do families with breast cancer alone, the authors performed additional analyses to examine whether the previously observed associations with waist/hip ratio differed when family history of breast cancer was partitioned according to whether or not ovarian cancer was also present in a close relative. Between 1986 and 1990, 620 incident cases of breast cancer were identified in a cohort of 37,105 postmenopausal Iowa women. A family history of breast cancer in first-degree relatives was associated with a relative risk of 1.34 (95% confidence interval (CI) 1.07-1.69); a family history of both breast cancer and ovarian cancer was associated with a relative risk of 2.36 (95% CI 1.12-4.98). Consistent with the authors' findings after 4 years of follow-up, a high waist/hip ratio (> or = 80th percentile vs. < 80th percentile) was associated with increased risk of breast cancer in the presence of a family history of breast cancer (relative risk (RR) = 2.10, 95% CI 1.43-3.09) but not in the absence of a family history of breast cancer (RR = 1.12). The combination of a high waist/hip ratio with a family history of breast and ovarian cancer was associated with 4.83-fold increased risk (95% CI 1.55-15.1). Neither a family history of breast cancer nor a family history of ovarian cancer was associated with significantly increased risk in the absence of a high waist/hip ratio.

Reduced risk of colon cancer with high intake of vitamin E: the Iowa Women's Health Study

Antioxidant micronutrients, including vitamin E, vitamin C, the carotenoids, and selenium, defend the body against free radicals and reactive oxygen molecules, suggesting a potential for these dietary components in cancer prevention. To investigate whether high intakes of antioxidant micronutrients protect against colon cancer in humans, we analyzed data from a prospective cohort study of 35,215 Iowa women aged 55-69 years and without a history of cancer who completed a dietary questionnaire in 1986. Through 1990, 212 incident cases of colon cancer were documented. Adjusted for age, total vitamin E intake was inversely associated with the risk of colon cancer (P for trend < 0.0001); the relative risk for the highest compared to the lowest quintile was 0.32 [95% confidence interval (95% CI) 0.19, 0.54]. Further adjustment for total energy intake and other risk factors in proportional hazards regression had little effect on these estimates. The association was not uniform across age groups: the multivariate relative risk of colon cancer for the highest compared to the lowest quintile of total vitamin E intake was 0.16 (95% CI 0.04, 0.70) for those 55-59 years old, 0.37 (95% CI 0.12, 1.16) for those 60-64 years old, and 0.93 (95% CI 0.27, 3.25) for those 65-69 years old. Multivariate-adjusted relative risks among women with higher total intakes of vitamins A and C and beta-carotene, and among users of selenium supplements, were not significantly different from 1.0. These prospective data provide evidence that a high intake of vitamin E may decrease the risk of colon cancer, especially in persons under 65 years of age.

Alcohol consumption and postmenopausal endometrial cancer: results from the Iowa Women's Health Study

At least three case-control studies have examined the association between alcohol consumption and endometrial cancer; two studies showed inverse associations, and a third a positive association. To our knowledge, no prospective studies of this association have been reported. The association between alcohol and endometrial cancer was examined in the Iowa Women's Health Study (United States), a prospective study of postmenopausal women. Information on alcohol consumption and other variables was obtained through a mailed questionnaire in January 1986. Through December 1990, 167 incident endometrial cancer cases occurred in the at-risk cohort of 25,170 women. Multivariate-adjusted relative risks (RR) and 95 percent confidence intervals (CI) were computed using Cox proportional hazards regression controlling for age, body mass index (BMI), parity, age at menopause, and noncontraceptive estrogen use, and to determine multiplicative interactions. The RRs of endometrial cancer associated with < 4.0 and > or = 4.0 g of alcohol per day compared with abstainers were 0.7 (CI = 0.5-1.1) and 1.0 (CI = 0.7-1.6), respectively. No statistically significant association between endometrial cancer and consumption of either beer, wine, or liquor was observed. There was no interaction between alcohol and any other endometrial cancer risk factors, including BMI or noncontraceptive estrogen use. These data do not support an association between alcohol and endometrial cancer among postmenopausal women.

Transfusion history and cancer risk in older women

OBJECTIVE

To test the hypothesis that history of blood transfusion is associated with an increased incidence of cancer in older women.

DESIGN

Prospective cohort study.

SETTING

General community in the state of Iowa.

PARTICIPANTS

Random sample of 37,337 cancer-free Iowa women ages 55 to 69 years.

MEASUREMENTS

Transfusion history was assessed with a mailed questionnaire completed in January 1986. Cancer incidence in 5 years was ascertained by a population-based cancer registry.

RESULTS

Women who had ever received a blood transfusion were at an increased risk for non-Hodgkin lymphoma (relative risk (RR) = 2.20; 95% CI, 1.35 to 3.58) and kidney cancer (RR = 2.53; CI, 1.34 to 4.78). The relative risks for these cancers were greater with decreasing time from first transfusion. No increased risk occurred for cancers of the breast, lung, uterine corpus, ovary, pancreas, colon, rectum, skin (melanoma), or for all cancers considered together.

CONCLUSION

These findings suggest that previous blood transfusion may be a risk factor for non-Hodgkin lymphoma and kidney cancer but is not associated with the most common neoplasms.

Relation of calcium, vitamin D, and dairy food intake to incidence of colon cancer among older women. The Iowa Women's Health Study

To investigate whether a high intake of calcium, vitamin D, or dairy products may protect against colon cancer, the authors analyzed data from a prospective cohort study of 35,216 Iowa women aged 55-69 years without a history of cancer who completed a dietary questionnaire in 1986. Through 1990, 212 incident cases of colon cancer were documented. Adjusted for age, intakes of calcium and vitamin D were significantly inversely associated with the risk of colon cancer. The relative risks for the highest quintile of intake as compared with the lowest were 0.52 (95% confidence interval (CI) 0.33-0.82) for calcium and 0.54 (95% CI 0.35-0.84) for vitamin D. After multivariate adjustment, the trends were no longer statistically significant and the relative risks for the highest versus the lowest quintiles of calcium and vitamin D intakes were attenuated: 0.68 (95% CI 0.41-1.11) for calcium and 0.73 (95% CI 0.45-1.18) for vitamin D. Although the multivariate-adjusted findings did not reach statistical significance at p < or = 0.05, when considered in the context of the whole body of literature on this subject, they are consistent with a possible role for calcium or vitamin D in modestly reducing colon cancer risk.

Platelet-derived growth factor and risk factors for colorectal cancer

Platelet-derived growth factor (PDGF) is a potent mitogen for a variety of cells. Abnormal PDGF activity has been reported in many chronic diseases including cancer. Existing data suggest that fluctuations or reset homeostasis in normal growth factor production due to specific agents or changes in cellular environment are potential mechanisms of colonic carcinogenesis. Currently identified risk factors for colorectal cancer include diet, non-steroidal anti-inflammatory drug use, alcohol consumption and physical activity. Certain constituents of diet, including retinoids, fish oils and soybeans, inhibit the activity of PDGF and could reduce paracrine stimulation of the colonic epithelium. Aspirin and physical activity, through reduction in platelet aggregation, may inhibit platelet release of PDGF and lead to reset homeostasis. Alcohol affects platelet aggregation and, depending on consumption patterns, could alter platelet release of PDGF. It is important to determine which of these environmental factors may result in transient effects on growth factor activity and which result in long-term adaptive responses. Further studies could examine the impact of these risk factors on (1) growth factor communication between colonic epithelial cells and fibroblasts in vitro and (2) PDGF concentrations and mitogenic activity in blood and tissue obtained in population-based studies of colorectal cancer.

Sex differences in colonic function: a randomised trial

There are sex differences in large bowel cancer rates and a variety of other gastrointestinal disorders possibly because of differences in gut biology. To determine whether men and women have different gastrointestinal responses when consuming identical intakes of dietary fibre, 16 women and 18 men consumed liquid formula diets and 'quick breads' with 0 g, and 10 g, and 30 g of fibre as wheat bran and vegetable fibre. The five test diets were consumed in random order, each treatment lasting 23 days. Mean transit time was faster (p = 0.02), and stool weights (g/day) were greater (p = 0.0005) for men than women. Neutral detergent fibre (NDF) excretion was greater in men (p = 0.01), and women tended to digest more NDF (p = 0.06). Men and women seemed to respond differently to wheat bran and vegetable fibre with regard to NDF excretion and digestibility. There were no gender differences in the faecal pH or moisture content. Concentrations and daily excretion of the secondary bile acids, lithocholic and deoxycholic acid, were greater for men than women (p < 0.05). Gender differences in bowel function and bile acid excretion, observed when men and women consumed the same amounts of dietary fibre, may be relevant for understanding colonic disease aetiology and for undertaking future dietary intervention trials.

Food-group consumption and colon cancer in the Adelaide Case-Control Study. I. Vegetables and fruit

Previous epidemiologic studies have shown an inverse association between vegetable and fruit consumption and risk of colon cancer. Vegetables and fruit contain a large number of potentially anti-carcinogenic substances, thus lending biological plausibility to this association. We conducted a case-control study in Australia, comparing 220 persons with histologically confirmed incident adenocarcinoma of the colon with 438 age- and gender-matched controls. Cases were identified via the South Australian Cancer Registry (1979-80); controls were randomly selected from the electoral roll. All participants completed a 141-item food-frequency questionnaire and were interviewed regarding demographic and other information. Consumption of 15 vegetable and fruit groups was investigated. Odds ratios (OR) for quartiles of consumption were derived using conditional logistic regression. All analyses were conducted separately for females and males. For females, greater intakes of onions and legumes were associated with decreased risk, with protein-adjusted OR of 0.48 and 0.53 respectively. Greater intakes of raw fruit and cabbage were associated with protein-adjusted OR of 0.76 and 0.71 respectively. For males, greater intakes of onions, green leafy vegetables, legumes, carrots and cabbage were associated with protein-adjusted OR in the range of 0.72 to 0.77. Consumption of potatoes was positively associated with risk in both genders. All 95% confidence intervals included 1.0. Analyses stratified by colon-cancer sub-site showed no strong and consistent differences between sub-sites for the vegetable and fruit associations. Results for meat, poultry, seafood, dairy foods and eggs are presented in a companion report.

Food-group consumption and colon cancer in the Adelaide Case-Control Study. II. Meat, poultry, seafood, dairy foods and eggs

We conducted a case-control study in Australia, comparing 220 persons with histologically confirmed incident adenocarcinoma of the colon with 438 age- and gender-matched controls. Cases were identified via the South Australian Cancer Registry (1979-80); controls were randomly selected from the electoral roll. All participants completed a 141-item food-frequency questionnaire and were interviewed regarding demographic and other information. Consumption of 8 groups of foods from animal sources was investigated. Odds ratios (OR) for quartiles of consumption were obtained using conditional logistic regression. All analyses were conducted separately for females and males. The most striking finding was a positive association for egg consumption in females, with an unadjusted OR of 2.4 (1.1-5.3) for consumption in the uppermost quartile. The uppermost septile of egg consumption was associated with an unadjusted OR of 6.3 (1.5-26.1) and a dose-response pattern was suggested. Intakes of red meat, liver, seafood, and dairy foods were also weakly positively associated with risk in females. In males, intakes of red meat and poultry were weakly positively associated with risk with unadjusted ORs of 1.5 (0.8-2.8) and 1.4 (0.7-2.6) respectively. The ratio of intake of red meat to poultry and seafood was also positively associated with risk in males, with an unadjusted OR of 1.4 (0.8-2.6). Interpretation of analyses stratified by colon cancer subsite was limited by the low number of subjects in each sub-site stratum, yet the results were somewhat supportive of a stronger risk associated with animal foods in the proximal than in the distal colon. The results for egg consumption suggest a role for cholesterol in the etiology of colon cancer, particularly in proximal cancer for females. Results for vegetable and fruit consumption are presented in a companion report.

Vegetables, fruit, and lung cancer in the Iowa Women's Health Study

Previous epidemiological studies have shown an inverse association between vegetable and fruit consumption and lung cancer risk; few of these studies have been prospective or have focused upon women. In 1986, we assessed food intake in 41,837 Iowa women, aged 55 to 69 yr, with a mailed 127-item food frequency questionnaire. After 4 years of follow-up, 179 incident cases of lung cancer were identified via the Iowa Surveillance, Epidemiology, and End Results cancer registry. After specific exclusion criteria were applied, a nested case-control comparison of 138 cases with 2,814 randomly selected noncases was undertaken. Intakes, in the upper-most quartile, of 11 vegetable and fruit groups, as well as of the nutrients beta-carotene and vitamin C, were explored. High intakes of all vegetables and fruit, all vegetables, and green leafy vegetables were each associated with an approximate halving of risk: age-, smoking-, and energy-adjusted odds ratios (ORs) were 0.49 (95% confidence interval, 0.28-0.86), 0.50 (95% confidence interval, 0.29-0.87), and 0.45 (95% confidence interval, 0.26-0.76), respectively. A lower lung cancer risk was also seen for all fruit (adjusted OR = 0.75 for high consumption), high vitamin C vegetables and fruit (OR = 0.75), carrots (OR = 0.71), and brocolli (OR = 0.72) and for the nutrients beta-carotene (OR = 0.81) and vitamin C (OR = 0.81) (all 95% confidence intervals included 1.0). Lung cancer risk was unrelated to consumption of the three food groups defined as "high-carotenoid" (beta-carotene, lutein, and lycopene) and tomatoes. In an analysis stratified by histological type of lung cancer, the strongest inverse associations for vegetables and fruit were seen for large cell carcinoma. Analysis by smoking status showed the inverse associations for most vegetable and fruit groups with lung cancer risk to be stronger for exsmokers than for current smokers. Results from the stratified analyses must be interpreted with caution because of the small number of cases in each stratum.

Colon cancer--do the nutritional epidemiology, the gut physiology and the molecular biology tell the same story?

Colon carcinogenesis models exist at epidemiologic, physiologic and molecular biologic levels. Thinking about the coherence of such models is useful both to inform colon cancer research and because the reasoning process may be generalizable. The consistent epidemiologic risk factors are low vegetable/fiber and high fat/meat/protein intakes. Others include physical activity, alcohol and reproduction. These epidemiologic risk factors appear to map to physiologic variables that provide mechanistic explanations for the associations: higher bile acids, fiber fermentation and effects of specific anticarcinogens found in vegetables. The possibility that the meat/fat association is due to carcinogens or promoters produced in cooked foods adds complexity to the physiologic model. As a link across genetics, physiology and epidemiology, the role of acetylator status is considered. Finally, whether relationships might exist between the epidemiologic/physiologic risk factors and the recently described molecular genetic changes and other colon cancer molecular mechanisms is considered.

Calcium and colorectal epithelial cell proliferation: a preliminary randomized, double-blinded, placebo-controlled clinical trial

BACKGROUND

Colonic epithelial cell proliferation is increased in patients at high risk for colon cancer. Calcium administration has ameliorated the proliferative changes in rodents, and findings in small, uncontrolled clinical trials have suggested similar effects in humans.

PURPOSE

This preliminary, double-blind, randomized clinical trial was designed 1) to investigate whether supplemental calcium will reduce colonic epithelial cell proliferation in patients with sporadic adenomas who consume a high-fat, Western-style diet; 2) to determine the sample size (number of scorable crypts per person) needed to achieve adequate statistical power; and 3) to evaluate the feasibility of full-scale clinical trials.

METHODS

Twenty-one sporadic adenoma patients were treated daily with placebo or 1200 mg of supplemental calcium. To determine colonic epithelial cell proliferation, we used tritiated thymidine labeling of colon crypt epithelial cells in rectal biopsy specimens and calculated the percentage of labeled cells (labeling index [LI]). Two pathology technician "readers" independently scored each specimen, and inter-reader reliability was determined. Subjects remained on their usual diet during the study, and intake of calories, calcium, total fat, and vitamin D did not differ substantially among them. We calculated curves for statistical power to determine the number of scorable crypts needed per person for detection of a statistically significant difference (P < .05) of 1.0% in mean LI.

RESULTS

The pooled baseline LI was 4.7%. In the calcium-treated group, the LI increased 0.6% (proportional increase, 12.8%); in the placebo-treated group, it decreased 0.5% (proportional decrease, 10.6%). The difference between change in the mean LI from baseline to 8 weeks' follow-up in the placebo group versus the calcium group was not statistically significant. The intraclass correlation coefficient for inter-reader reliability for the baseline LI was .66. Analyses indicated scoring eight crypts sufficient for estimates of the LI adequate for between-group comparisons, a level achieved in 81% of biopsy specimens.

CONCLUSIONS

Calcium carbonate supplements delivering 1200 mg elemental calcium daily may not decrease colonic epithelial cell proliferation over an 8-week period in sporadic adenoma patients. In future trials measuring the LI, consideration should be given to ensuring adequate numbers of scorable crypts and to the impact of inadequate biopsy procedures, labeling failure, reader reliability, and participant withdrawal. Our findings support the feasibility of a full-scale clinical trial to further study the relationships among dietary calcium, colonic epithelial cell proliferation, and colorectal cancer.

Difficulty becoming pregnant and family history as interactive risk factors for postmenopausal breast cancer: the Iowa Women's Health Study

We recently provided data from a prospective cohort study of postmenopausal women which suggested that a first livebirth at age 30 or older (cf before age 20) was associated with a twofold increased risk of breast cancer in women without a family history, but a 5.8-fold higher risk in women with a positive family history. To address the question of whether these observations reflect difficulty becoming pregnant or maintaining a pregnancy, we performed additional analyses in which the outcome of each pregnancy was considered. During five years of follow-up, 620 incident cases of breast cancer were identified in the 37,105 women at risk. There was little evidence for an increased risk associated with a history of spontaneous abortion (relative risk [RR] = 1.1; 95 percent confidence interval [CI] = 0.9-1.4), nor was the risk higher among women who reported two or more spontaneous abortions in consecutive pregnancies (RR = 1.0, CI = 0.7-1.4). Although women who reported that they had tried unsuccessfully to become pregnant had only slightly and nonsignificantly elevated risks of breast cancer (RR = 1.1, CI = 0.9-1.3), a more pronounced and statistically significant association was noted in women with a positive family history (RR = 2.1, CI = 1.4-3.2). There was a strong inverse association between failure to become pregnant and parity (P < 0.0001); nearly 50 percent of the nulliparous married women reported having tried and failed to become pregnant, whereas the frequency was only 6.8 percent among married women with five or more livebirths.(ABSTRACT TRUNCATED AT 250 WORDS)

Familial clustering of colon, breast, uterine, and ovarian cancers as assessed by family history

The aggregation of colon, endometrial, ovarian, and possibly breast cancers in families has been described as a "cancer family syndrome" (now called Lynch syndrome II). To determine if the familial clustering of these malignancies was more common in women with cancer than without, we analyzed data from the Iowa Women's Health Study (IWHS), a population-based sample of 41,837 women aged 55-69 years. Self-reported information was collected on history of colon, uterine, ovarian, and breast cancers in female first-degree relatives. A family history of cancer of the breast (odds ratio [OR] = 1.4), colon (OR = 1.3), and uterus (OR = 1.3), but not ovary (OR = 1.2), was significantly more common among women with a personal history of any of these four cancers (all P < 0.05); the pattern of the ORs suggested strongly that the clustering tended to be site-specific. Age-adjusted relative risks (RR) of incident colon cancer over 5 years of follow-up (N = 237) were calculated with regard to family history. Colon cancer incidence was increased among women with a family history of breast (RR = 1.3), uterine (RR = 1.4), colon (RR = 1.5), and ovarian (RR = 1.3) cancers, although none of the risk estimates achieved statistical significance. RR was, however, significantly related to the number of different cancer sites reported among family members (Ptrend = 0.008). These data on a representative sample of postmenopausal women suggest that family histories of colon, breast, uterine, and ovarian cancers are associated with an increased risk of cancer at the same site, but provide little support for the hypothesis that Lynch syndrome II is a non-random occurrence.