Cigarette smoking and other behavioral risk factors for recurrence of colorectal adenomatous polyps (New York City,NY, USA)

Adenomatous polyps (hereinafter referred to as adenomas) are known precursors of colorectal cancer. Cigarette smoking has been associated with adenomas but not with colorectal cancer, while alcohol and fat intake have been associated with both adenomas and cancer in some studies. Approximately 30 percent of patients with resected adenomas develop another adenoma within three years. This case-control study explores the association of cigarette smoking with adenoma recurrence. Between April 1986 and March 1988, we administered a questionnaire to colonoscoped patients aged 35 to 84 years in three New York City (NY, USA) practices. We compared 186 recurrent polyp cases (130 males, 56 females) and 330 controls (187 males, 143 females) who had a history of polypectomy but normal follow-up colonoscopy, by cigarette-smoking pack-years adjusted for possible confounders. Risk for a metachronous or recurrent adenoma was significantly greater in the highest quartile of smokers than in never-smokers among both men (odds ratio [OR]=1.8,95 percent confidence interval [CI]=1.0–3.4) and women (OR=3.6, CI=1.7–7.6). Adjustment for time since smoking cessation reduced risk only slightly, as did adjustment for dietary fat intake, which itself remained significant. No association was found between alcohol intake and risk of recurrence. Cigarette smokers appear to have an elevated risk of adenoma recurrence that is not eliminated entirely by smoking cessation. Intervention trials that use adenoma recurrence as an endpoint should take smoking into account.This work was supported in part by grants from the National Cancer Institute (RO1-CA37196 and ST34CA09529) and the Aaron Diamond Foundation.     

Parity and other reproductive factors and risk of adenomatous polyps of the distal colorectum (United States)

Evidence for an effect of reproductive factors on colorectal carcinogenesis is inconsistent and little is known about their role in development of precursor adenomatous polyps. We evaluated the relation between reproductive factors and distal colorectal adenomas (n = 982) during14 years of follow up of 26,983 participants in the Nurses' Health Study(United States). The women were free of diagnosed cancer or polyps in 1980,underwent endoscopy 1980-94, and had reported on their parity, oral contraceptive (OC) use, and ages at menarche, first term-pregnancy, and menopause. We calculated relative risks (RR) and 95 percent confidence intervals (CI) using multiple logistic regression. Women with higher parity had an increased risk of adenomas of the distal colorectum (P trend = 0.004;6+ cf 0 parity: RR = 1.3, CI = 0.9-1.8) or distal colon (P trend = 0.002, RR= 1.7, CI = 1.2-2.6). This association was significantly stronger among women with a family history of colorectal cancer ( P interaction = 0.03); comparing6+ term-pregnancies with nulliparity, among those with a family history, the RR for distal colon adenoma was 3.2 (CI = 1.4-7.2), while among those without a family history, the RR was 1.3 (CI = 0.8-2.2). We observed no association for distal colorectal adenoma and age at menarche, age at first term-pregnancy, ever use of OCs, or menopausal status. Further work is needed to clarify the relation of parity with colon adenoma risk. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reproductive factors and colon cancer: the influences of age,tumor site,and family history on risk (Utah,United States)

The Utah (United States) Population Database was used to evaluate the associations between reproductive factors and colon cancer risk and the impact that family history, age at diagnosis, and tumor site have on these associations. From the cohort of (White) women in the database, all first-primary cases of colon cancer (n=819) and controls who had complete fertility information (n=3, 202) were examined. The majority of tumors (68.6 percent) among women diagnosed at age 64 years or less were in the distal segment of the colon, while among women 65 or older, the majority of tumors (55.7 percent) were proximal. Women diagnosed before age 65 had a lower risk of colon cancer with increasing numbers of liveborn children (odds ratio [OR]=0.6, 95 percent confidence interval [CI]=0.3–0.9 for women with five or more children compared with women with one or two children). A long interval between first and second births (first birth-interval) was associated with increased risk of tumors in the distal segment of the colon (OR=1.4, CI=1.0–2.0) and among women diagnosed before age 65 (OR=1.6, CI=1.0–2.5); a longer, average birth-interval was associated with increased risk of proximal tumors (OR=1.5, CI=1.1–2.1). A longer, first birth-interval increased the risk associated with a family history of colon cancer, as did a longer average birth-interval and an older age at first or last birth. From these data, it appears that reproductive factors have heterogeneous effects on the risk of colon cancer that vary with age at diagnosis, tumor site, and family history of disease.This study was supported by grant and contract numbers CA48998 and CN0552 from the US National Cancer Institute. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute.     

Reproductive factors and risk of brain,colon, and other malignancies in Iowa (United States)

The influence of parity on the risk of cancers of the female breast and reproductive organs is well established. However, non-reproductive sites have received less attention. Mail questionnaire data gathered from incident female cases (169 brain; 332 colon; 260 rectal; 145 kidney; and 169 pancreas cancers), and 821 populationbased controls in Iowa (United States) were used to measure the effect of parity and age at first birth on risk of these malignancies. Relative to nulliparous women, ever-parous women were at significantly decreased risk of brain cancer (odds ratio [OR]=0.44, 95 percent confidence interval [CI]=0.3–0.7) and of colon cancer (OR=0.67, CI=0.5–0.97), after adjustment for age and other risk factors. The OR for the other sites did not differ significantly from 1.0. The lower risk of brain cancer among parous women was similar in younger and older age groups, in patients diagnosed with glioblastoma and astrocytoma, and among ever- and never-smokers. The findings for colon cancer are consistent with observations from other studies. In the context of limited laboratory and clinical evidence implicating hormones in brain neoplasia, these findings may suggest a role for hormonal factors in brain cancer etiology. Hormonal factors deserve more detailed future consideration as risk factors in brain cancer.Dr Cantor is with the Environmental Epidemiology Branch, National Cancer Institute, Bethesda, MD, USA. Dr Lynch and Ms Johnson are with the Department of Preventive Medicine and Environmental Health, University of Iowa, Iowa City, IA, USA. Address correspondence to Dr Cantor, Environmental Epidemiology Branch, National Cancer Institute, Executive Plaza North, Suite 443, Bethesda, MD 20892, USA. Supported in part by United States National Cancer Institute research contracts (NCI-NO1-CP-51026 and NCI NO1-CP-85614) and by a Public Health Service Preventive Oncology Academic Award (5 KO7 CA01181-05).     

A nested case-control study of mammographic patterns,breast volume,and breast cancer (New York City,NY, United States)

The relations of Wolfe mammographic patterns, quantitative mammographic densities, and mammographically estimated breast size to breast cancer risk were investigated prospectively in a case-control study nested in the New York University Women's Health Study, a cohort of 14,291 women in New York City, NY (United States). The archived mammograms of 197 breast cancer cases who were identified during the first 5.5 years of the study and of 521 individually matched controls from the same cohort were retrieved and classified according to Wolfe parenchymal patterns and mammographic densities by two expert radiologists. Breast size and volume were estimated on the mammogram's cranio-caudal projection. In both premenopausal and postmenopausal subjects, the risk of breast cancer increased progressively with increasing density and percent density area. A significantly increased risk was found also for Wolfe pattern DY in premenopausal women and P2 pattern in postmenopausal subjects. In premenopausal women, mammographically determined breast volume and breast height also were associated positively with breast cancer risk. Although the results of the present study confirmed that mammographic parenchymal patterns and densities were important predictors of breast cancer risk, their practical use in screening seems limited due to the high prevalence of high risk patterns.This work was supported by Grants CA51921, CA34588, CA13343, and CA16087 from the US National Cancer Institute and by Grant ES00260 from the National Institute of Environmental Health Sciences.     

Reproductive factors and family history of breast cancer in relation to plasma estrogen and prolactin levels in postmenopausal women in the Nurses' Health Study (United States)

Parity, age at first birth, age at menarche, and a family history of breast cancer have each been associated consistently with breast cancer risk. Whether this increase in risk is mediated, at least in part, through changes in endogenous hormone levels is unclear. We conducted a cross-sectional study of the relationships between these factors and plasma hormone levels in 216 healthy postmenopausal women in the Nurses' Health Study (United States). The hormones evaluated were estradiol, percent and total free estradiol, percent and total bioavailable estradiol, estrone, estrone sulfate, and prolactin. After controlling for age, body mass index (weight/height²), and alcohol use, we observed inverse associations between estrone sulfate and parity (r=–0.15, P=0.03) and between percent bioavailable estradiol and age at first birth (r=–0.17, P=0.02). Although women with a family history of breast cancer tended to have higher estrogen levels compared with women without such history, the differences were not statistically significant. Age at menarche was not related significantly to any of the hormones. These data provide some additional evidence that the inverse relationship observed between parity and breast cancer risk may be mediated, at least in part, through decreased estrogen levels. Our data do not support a substantial influence of either family history of breast cancer or age at menarche on postmenopausal estrogen or prolactin levels.Authors are with the Channing Laboratory (Drs Hankinson, Colditz, Hunter, Manson, Willett, Stampfer, Speizer) and Divislon of Preventive Medicine (Dr Manson), Brigham and Women's Hospital and Harvard Medical School, Boston, MA (USA); Departments of Nutrition (Drs Willett, Stampfer), and Epidemiology (Drs Hankinson, Colditz, Hunter, Willett, Stampfer), Harvard School of Public Health, Boston, MA; and the Departments of Obstetrics and Gynecology and Medicine, University of Massachusetts Medical School, Worcester, MA (Dr Longcope). Address correspondence to Dr Hankinson, Channing Laboratory, 180 Longwood Ave., Boston, MA 02115, USA. This research was supported by research grants CA40356 and CA49449 from the US National Institutes of Health, Bethesda, MD. Dr Manson is a recipient of a Merk/Society for Epidemiologic Research grant award.     

Physical activity, obesity, and risk of colorectal adenoma in women (United States)

The relationship between physical inactivity, body mass index (BMI) (wt[kg]/ht[m]²), and pattern of adipose distribution with risk of colorectal adenomas (precursors of cancer) was examined in 13,057 female nurses in the United States, 40 to 65 years of age in 1986, who had an endoscopy between 1986 and 1992. From 1986 to 1992, 439 participants were newly diagnosed with adenomas of the distal colorectum. After controlling for age, prior endoscopy, parental history of-colorectal cancer, smoking, aspirin, and intakes of animal fat, dietary fiber, folate, methionine, and alcohol, physical activity was associated inversely with risk of large (1 cm) adenomas in the distal colon (relative risk [RR]=0.57,95 percent confidence interval [CI]=0.30–1.08, comparing high and low quintiles of average weekly energy expenditure from leisure-time activities; P trend = 0.05). Much of the benefit came from activities of moderate intensity such as brisk walking. In addition, BMI was associated directly with risk of large adenomas in the distal colon (multivariate RR=2.21 [CI=1.18–4.16], P trend = 0.0001, for BMI 29 cf <21 kg/m²). Waist circumference and the waist-to-hip ratio (WHR) were not related significantly to adenoma independently of BMI, but women with both a high BMI and high WHR were at greater risk of large colon adenoma (multivariate RR=1.99, CI=0.98–4.05) than women with high BMI but relatively low WHR (multivariate RR=1.35, CI=0.61–2.97). BMI was not related to small (<1 cm) adenoma risk but physical activity had an inverse association with small adenomas in the distal colon (multivariate RR=0.68, CI=0.40–1.15, P trend = 0.03). The relationships between BMI or physical activity were considerably weaker and inconsistent for rectal adenomas. These results, in women, support an inverse association between physical activity and occurrence or progression of ademonas in the distal colon; obesity is associated with an elevated risk of large adenomas.The authors are with the Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA. The authors are also affiliated with the Department of Nutrition, Harvard School of Public Health, Boston, MA (Drs Giovannucci, Stampfer, and Willett), and the Department of Epidemiology, Harvard School of Public Health, Boston, MA (Drs Colditz, Stampfer, and Willett). Address correspondence to Dr Giovannucci, Channing Laboratory, 180 Longwood Avenue, Boston, MA 02115, USA. The work was supported by research grant numbers CA 40935 and CA 55075 from the US National Institutes of Health. Dr Colditz is supported by a Faculty Research Award (FRA-398) from the American Cancer Society.     

Strenuous physical activity in young adulthood and risk of breast cancer (United States)

The epidemiologic data on the relation between strenuous physical activity and breast cancer are limited and inconsistent. Because risk of breast cancer may be influenced by ovarian function which, in turn, is modulated by physical activity, the hypothesis that exercise may be associated with a reduced risk of breast cancer merits further investigation. We, therefore, conducted a large case-control study in 1988–91, and interviewed 6,888 women (17 to 74 years of age) with breast cancer in Maine, Massachusetts, New Hampshire, and Wisconsin (United States). Interviewed controls (9,539 women, 18 to 74 years of age) were selected randomly from lists of licensed drivers (for younger women) or from a roster of Medicare enrollees (for older women). We used multivariate adjusted odds ratios (OR) and 95 percent confidence intervals (CI) from logistic regression models to estimate relative risks between self-reported physical activity when 14 to 22 years of age and breast cancer. When compared with sedentary controls, women who reported any strenuous physical activity during ages 14 to 22 years had a modest reduction in the risk of breast cancer (OR=0.95, CI=0.93–0.97). However, those who exercised vigorously at least once a day had a 50 percent reduction in risk of breast cancer (OR=0.5, CI=0.4–0.7). These data support the hypothesis that women who are physically active have a reduced risk of breast cancer.This project is funded by grants (R01 CA 47147 and R01 CA 47305) from the US Public Health Service.Dr Mittendorf was also supported by National Research Service Award No. 5 T32 ES07069.     

Sexual, reproductive, and other risk factors for adenocarcinoma of the cervix: results from a population-based case-control study (California, United States)

The incidence of adenocarcinoma of the cervix increased steadily in young women in the United States between the early 1970s and the mid-1980s. Despite this increase, little is known about the etiology of this cancer, although a role for risk factors for both squamous cell carcinoma of the cervix and endometrial adenocarcinoma has been suggested. Incident cases of adenocarcinoma of the cervix diagnosed in women born after 1935 (ages 42 to 56 at diagnosis) were identified from the Los Angeles (California) County Cancer Surveillance Program (LACCSP). Data from personal interviews with 195 cases and 386 controls (matched on age, race, and neighborhood) were analyzed. Compared with women in the highest categories of education and income, women in the lowest categories had a 2.5 and 3.1-fold elevated risk of adenocarcinoma of the cervix. Number of sexual partners, especially before age 20, was strongly predictive of risk (odds ratio = 5.6, 95 percent confidence interval = 1.4–22.0 for 10 or more compared with no partners before age 20). Smoking was not associated significantly with risk. Weight gain and long-term use of oral contraceptives increased risk, while long-term diaphragm use was protective. This study suggests that both sexual and hormonal factors are important etiologic factors for adenocarcinoma of the cervix.Drs Ursin, Pike, Preston-Martin, and Peters are with the Department of Preventive Medicine, University of Southern California School of Medicine, Los Angeles, CA, USA. Dr D'Ablaing, now deceased, was with the Department of Pathology at the University of Southern California School of Medicine. Address correspondence to Dr Ursin, Department of Preventive Medicine, University of Southern California Norris Comprehensive Cancer Center, 1441 Eastlake Ave., MS#44, P.O. Box 33800, Los Angeles, CA 90033-0800, USA. This study was supported by grants P01 CA1754 and CA 44401-05 from the US National Cancer Institute, and by the California Department of Health Services, through the California Public Health Foundation, as part of its statewide cancer reporting program, mandated by Health and Safety Code Sections 210 and 211.3. The ideas and opinions expressed herein are those of the authors, and no endorsement by the State of California Department of Health Services or the California Public Health Foundation is intended or should be inferred.     

Glycosylated hemoglobin and risk of colorectal cancer and adenoma (United States)

Objectives: The consistently observed epidemiologic associations of obesity and physical activity with colorectal cancer and precursor adenoma risk suggest that insulin and glucose control may be contributory. We evaluated the association of glycosylated hemoglobin (HbA_1c), a clinical indicator of average glycemia over the previous 2 months, and possibly, indirectly, a marker of average blood insulin level, with colorectal carcinogenesis.Methods: Among women in the Nurses' Health Study, who provided blood in 1989–90 and were diagnosed subsequently in 1989–94, we included 79 colorectal cancer cases and 156 matched controls, and 201 distal colorectal adenoma cases and 201 matched controls. HbA_1c concentrations in red blood cells were determined blindly by turbidometric immunoinhibition. Odds ratios (OR) and 95% confidence intervals (CI) were estimated from conditional logistic regression models.Results: HbA_1c level did not significantly differ between colorectal cancer cases (median 5.5%) and controls (5.5%, p = 0.5), although a small difference between adenoma cases (5.6%) and controls (5.5%, p = 0.06) was noted. Compared to the lowest tertile of HbA_1c (median 5.2%), women in the middle (median 5.5%, OR = 1.2, CI = 0.6–2.5) and upper (5.8%, OR = 1.2, CI = 0.6–2.7) tertiles were not at an increased risk for colorectal cancer. A modestly elevated risk of distal colorectal adenoma in the upper (median 5.8%, OR = 1.4, CI = 0.9–2.3) versus lower (median 5.3%) tertile could not be excluded. These associations were not appreciably altered after adjusting for known and suspected colorectal cancer risk factors.Conclusion: Over the range of levels observed in this relatively small sample of middle-aged women, prediagnostic HbA_1c does not clearly predict colorectal cancer and adenoma risk.     

A case-control study of maternal risk factors for thyroid cancer in young women (California,United States)

A population-based case-control interview study investigated whether reproductive factors are related to the striking female-over-male excess of thyroid cancer among women of reproductive age in Los Angeles County, CA (United States). As a separate component of that study, mothers of 153 cases and 140 controls who were age 40 or younger at diagnosis or reference date were interviewed by telephone to determine the significance of family and maternal risk factors in the subsequent development of thyroid cancer among the daughters. More case than control mothers experienced miscarriage prior to the index pregnancy (odds ratio [OR]=2.0, 95 percent confidence interval [CI]=1.1–3.5). Increased risk was associated with family history of thyroid cancer or other thyroid disease (OR=2.1, CI=1.2–3.6). More control than case mothers smoked during the index pregnancy (OR=0.6, CI=0.4–1.0); however, among mothers who smoked, case mothers smoked more. Case mothers experienced a greater increase in weight from minimum adult weight to weight at index pregnancy (P for trend = 0.01). Reports from mothers also confirmed the risk associated with the daughter's exposure to ionizing radiation from birth through adolescence; ionizing radiation remains the best-established risk factor for thyroid cancer.This study was funded by program project CA17054 from the National Cancer Institute.     

Serum hormone levels in relation to reproductive and lifestyle factors in postmenopausal women (United States)

Objectives: Endogenous sex hormones are thought to be involved in breast and endometrial cancers, but few studies have evaluated the relationships between hormones and risk factors for these diseases. Methods: We related serum hormone and sex-hormone binding globulin (SHBG) levels to reproductive and lifestyle risk factors in a cross-sectional study of 125 postmenopausal women in five geographic regions of the United States. Results: The estrogens were associated positively, while SHBG was associated negatively with body mass index (wt/ht 2). Estrone, (E1), estrone sulfate, and bioavailable estradiol (BioE2) were inversely associated with height. Androstenedione was positively associated with age at menopause, while androstenedione, E1, estradiol, and BioE2 were inversely associated with age at menarche. Weekly alcohol drinkers had higher hormone levels, and lower SHBG levels than those who abstained. Androstenedione and E1 decreased with increasing levels of nonrecreational activity. Conclusions: Several of these findings support the hypothesis that breast and endometrial cancer risk factors are mediated, in part, through increased endogenous hormone levels. The androstenedione findings are of interest in light of studies relating androstenedione to endometrial and possibly breast cancer. An association of age at menarche with E2, independent of androstenedione, may reflect increased aromatase activity in women with earlier menarche.     

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

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

Determinants of breast cancer detection among Wisconsin (United States) women, 1988–90

Early detection is advocated widely as the best method to reduce the high rate of breast cancer mortality in women. The purpose of this study was to describe the detection histories of women with breast cancer and to identify factors related to the method of detection. During the period 1988–90, 3,197 women with invasive breast cancer, identified through the Wisconsin (United States) tumor registry, were interviewed. The method of cancer detection (classified as self, screening mammography, or clinical breast examination [CBE]) was analyzed using polychotomous logistic regression. Fifty-five percent (1,754/3,197) of the women found their own cancers, while 35 percent (1,122/3,197) were detected by screening mammography. Compared with self-detection, the likelihood of non-localized disease was significantly lower for tumors detected by mammography (odds ratio [OR]=0.3, 95 percent confidence interval [CI]=0.2–0.4) and CBE (OR=0.6, CI=0.4–0.7). The likelihood of cancer being detected by screening mammography increased with increasing age, education, number of prior mammograms, family history, and body mass index (weight/height²) (BMI). Women in the highest BMI quintile were 2.3 times (CI=1.7–3.0) more likely than women in the lowest BMI quintile to have their cancers diagnosed by mammography. This association most likely results from breast tumors being more difficult to palpate in heavier women.This work was undertaken while Dr Reeves was an Epidemic Intelligence Officer, assigned to the Wisconsin Division of Health from the Division of Field Epidemiology, Centers for Disease Control and Prevention, Atlanta, GA, USA.     

Meat preparation and colorectal adenomas in a large sigmoidoscopy-based case-control study in California (United States)

The often observed association between red meat and colorectal cancercould be due in part to mutagens, such as heterocyclic amines (HCA), that arepresent in cooked meat. HCAs are highly mutagenic and cause intestinal tumorsin animals. The hypothesis that HCAs are also carcinogenic to humans remainsto be substantiated in epidemiologic studies. We determined the associationsof meat preparation and frequency of intake (proxy variables for HCAexposure, since HCA concentration depends on the type of meat and the way itis cooked) with the prevalence of distal colorectal adenomas in asigmoidoscopy-based case-control study of 488 matched pairs of subjects fromtwo California (United States) Kaiser Permanente Medical Centers. A more thantwofold difference in adenoma prevalence between subjects at extreme ends ofestimated HCA intake was observed. For subjects who ate red meat more thanonce per week, fried it more than 10 percent of the time, and ate it with adarkly browned surface, compared with subjects who ate red meat one time orless per week, fried it 10 or less percent of the time, and ate it with alightly browned surface, the odds ratio was 2.2 (95 percent confidenceinterval = 1.1-4.3). Adenoma prevalence also increased with frequency offrying red meat (P trend = 0.004). These results are consistent with acarcinogenic effect of HCA.     

Screening endoscopy and risk of colorectal cancer in United States men

Objectives: The purpose of this study was to describe the effect of screening endoscopy (sigmoidoscopy or colonoscopy) on colorectal cancer incidence and mortality. Methods: We used data from a prospective cohort study of 24,744 men aged 40 to 75 years in 1986, free from cancer and colon polyps, followed until 1994. The outcomes are diagnosis of colorectal cancer and death from colorectal cancer. Results: Screening endoscopy in 1986-87 was associated with a lower risk of all colorectal cancer (multivariate relative risk [RR]=0.58, 95 percent confidence interval [CI]=0.36-0.96); cancer in the distal colon or rectum (multivariate RR=0.40, CI=0.19-0.84); Dukes stage A&B (multivariate RR=0.66, CI=0.35-1.25); and Dukes stage C&D (multivariate RR=0.50, CI=0.20-1.26) colorectal cancer; and death from colorectal cancer (multivariate RR=0.56, CI=0.20-1.60), after adjusting for age and a wide range of colon cancer risk factors. Screening endoscopy in 1988-87 appeared to provide strong protection against distal stage C&D cancers (age-adjusted RR=0.16, CI=0.02-1.23) but no protection against proximal stage C&D cancers (age-adjusted RR=0.96, CI=0.32-2.91). Conclusions: This study provides strong evidence for a protective effect of screening sigmoidoscopy on colorectal cancer incidence and mortality and supports recommendations for screening sigmoidoscopy as an approach to colon cancer prevention.     

A prospective study of menopausal hormones and risk of colorectal cancer (United States)

The relation of colorectal cancer and its subsites with use ofmenopausal hormones was evaluated in the United States among 40,464postmenopausal women, 41 to 80 years of age, who initially volunteered for anationwide breast-cancer screening program and were followed for an averageof 7.7 years. Ever-use of menopausal hormones was not associated with risk oftotal colorectal cancers (relative risk [RR] = 0.99, 95 percent confidenceinterval [CI] = 0.79-1.2) or cancers of the colon (RR = 1.1, CI = 0.81-1.6)or rectum (RR = 1.1, CI = 0.59-1.9). Recent hormone users, however, had asmall nonsignificant reduction in risk of colorectal cancer (RR = 0.78, CI =0.55-1.1), which was most pronounced for distal colon (RR = 0.68, CI =0.29-1.6) and rectal tumors (RR = 0.64, CI = 0.24-1.7). No effect wasobserved for former hormone users, and risk generally did not vary by timesince last use, type of regimen, or duration of use. However, the reducedrisk for recent users was stronger for users of five or more years'duration. These data show some lowering of colorectal cancer risk amongrecent menopausal hormone users of long duration.     

Recent oral contraceptive use and risk of breast cancer (United States)

We examined the association between recent oral contraceptive (OC) use and the risk of breast cancer in data from a large population-based case-control study in the United States. Cases (n=6,751) were women less than 75 years old who had breast cancer identified from statewide tumor registries in Wisconsin, Massachusetts, Maine, and New Hampshire. Controls (n=9,311) were selected randomly from lists of licensed drivers (if aged under 65 years) and from lists of Medicare beneficiaries (if aged 65 through 74 years). Information on OC use, reproductive experiences, and family and medical history was obtained by telephone interview. After adjustment for parity, age at first delivery, and other risk factors, women who had ever used OCs were at similar risk of breast cancer as never-users (relative risk [RR]=1.1, 95 percent confidence interval [CI]=10–1.2). Total duration of usealso was not related to risk. There was a suggestion that more recent use was associated with an increased risk of breast cancer; use less than two years ago was associated with an RR of 1.3 (CI=0.9–1.9). However, only among women aged 35 to 45 years at diagnosis was the increase in risk among recent users statistically significantly elevated (RR=2.0, CI=1.1–3.9). Use prior to the first pregnancy or among nulliparous women was not associated with increased risk. Among recent users of OCs, the risk associated with use was greatest among non-obese women, e.g., among women with body mass index (kg/m²) less than 20.4, RR=1.7, CI=1.1–2.8. While these results suggest that, in general, breast cancer risk is not increased substantially among women who have used OCs, they also are consistent with a slight increased risk among subgroups of recent users.Authors are with the University of Wisconsin Comprehensive Cancer Center, Madison, WI, USA (Dr Newcomb, Ms Trentham Dietz); NIEHS Epidemiology Branch, Research Triangle Park, NC (Dr Longnecker); Fred Hutchinson Cancer Research Center, Seattle, WA (Dr Surer); Department of Obstetrics and Gynecology, Pritzker School of Medicine, The University of Chicago, Chicago, IL (Dr Mittendorf); Department of Community and Family Medicine, Dartmouth Medical School, Hanover, NH (Dr Baron); Boston University, School of Public Health, Boston, MA (Dr Clapp); Department of Epidemiology and Department of Nutrition, Harvard School of Public Health, and Channing Laboratory, Harvard Medical School and Department of Medicine, Brigham and Women's Hospital, Boston, MA (Dr Willett). Address correspondence to: Dr Polly A. Newcomb, University of Wisconsin-Madison Comprehensive Cancer Center, 1300 University Ave., #4780, Madison, WI 53706, USA. Supported by Public Health Service (National Cancer Institute) grants R01 CA 47147 and R01 CA 47305.