Increasing incidence of colon and rectal cancer among Hispanics and American Indians in New Mexico (United States), 1969-94

Objectives: This study evaluates time trends in colon and rectal cancer incidence and mortality among the three major race/ethnic groups (Hispanics, American Indians, and non-Hispanic Whites) in New Mexico (United States). Methods: We used data from the New Mexico Tumor Registry (NMTR) and computed average annual age-standardized incidence and mortality rates. Colon cancer incidence rates were further examined by anatomical subsite. Estimated annual percent change (EAPC) in incidence and mortality over time were computed using Poisson regression. Results: Invasive colorectal cancer incidence rates increased from 1969-89 in all three race/ethnic groups, but decreased among non-Hispanic Whites in 1990-94, while rates continued to increase among minority populations, especially among minority men. Over the 26-year period, EAPC in colon cancer incidence among men was 3.6 percent for Hispanics, 4.7 percent for American Indians, and 0.7 percent for non-Hispanic Whites. Right-sided colon cancers were more common among American Indian women, and among all women aged 65 years and older. Mortality rates decreased steadily among non-Hispanic Whites over the study period, especially among women. Conclusions: Studies are needed to identify important modifiable risk factors and to develop strategies to increase the use of colorectal cancer screening-procedures among the minority populations.     

Cancer survival among American Indians in western Washington state (United States)

Cancer survival among American Indians is worse than among other races in some regions of the United States, but has not been studied among American Indians in Washington state. Our purpose was to evaluate cancer survival among American Indians included in the Seattle-Puget Sound Cancer Registry. We compared site-specific survival among American Indians (n=551) and Whites (n=110,899) diagnosed from 1974 to 1989 for five cancer sites. For all sites except prostate, the distribution of cancer stage at diagnosis for American Indians was not significantly different from the distribution for Whites, and a similar proportion of American Indians and Whites received cancer treatment. After adjustment for age differences between American Indians and Whites, American Indians experienced poorer survival from prostate, breast, cervical, and colorectal cancer. Poorer survival among American Indians persisted after adjustment for differences in cancer stage at diagnosis, lack of cancer treatment, and residence in a non-urban county. The survival experience among American Indians who were recorded as non-American Indians in the cancer registry but whe were listed as American Indians in Indian Health Service records was more favorable than that among persons initially coded as American Indians in the cancer registry. We conclude that cancer survival among American Indians in western Washington is poorer than that among Whites in the same region, and that factors other than age, differences in stage at diagnosis, lack of cancer treatment, and residence in non-urban counties account for this.This work was supported in part by finding from the US National Cancer Institute (grant Y02-CN-90667). The opinions expressed in this paper are those of the authors, and do not necessarily reflect the views of the Indian Health Service.     

Leisure-time physical activity in relation to breast cancer among young women (Washington, United States)

It has been hypothesized that women who participate in vigorous physical activity may have lower risk of breast cancer due to lower lifetime exposure to ovarian hormones. A population-based case-control study was conducted to investigate the association between leisure-time physical activity and risk of breast cancer among women aged 21 to 45 years. Cases were 747 women diagnosed with invasive breast cancer between 1983 and 1990 in three counties of western Washington state (United States), and were identified through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) registry. Controls were 961 women selected from the same area by random-digit telephone dialing. Physical activity was assessed through personal interview, with questions on frequency and duration of each type of recreational activity during the two-year period immediately prior to reference date (date of diagnosis for cases and a comparable assigned date for controls) and between ages 12 and 21. For the two-year time period before diagnosis, there was no association with frequency of activity (age-adjusted odds ratio [OR]=0.93, 95 percent confidence interval [CI]=0.71-1.22 for four or more episodes per week cf none), total hours spent in physical activity (age-adjusted OR=0.92, CI=0.71-1.22 for four or more hours per week cf none) or MET (metabolic equivalent energy expenditure unit) (age-adjusted OR=0.95, CI=0.73-1.23 for 18 or more METs per week cf none), nor any trend in risk with increasing activity levels. Similarly, there was no association between leisure activity during adolescence and breast cancer risk. These results were not confounded further by body mass index (wt/ht2), age at menarche, age at first full-term pregnancy, parity, family history of breast cancer, or other measured health behaviors. Our findings do not support a protective effect of leisure-time physical activity either in the adolescent years or in adulthood on breast cancer in young women.     

Physical activity in usual occupation and risk of breast cancer (United States)

We have used data from a large population-based case-control study inthe United States to evaluate the effect of occupational physical activity onbreast cancer risk. Women diagnosed with breast cancer identified from fourstate cancer registries, and controls randomly selected from lists oflicensed drivers or Medicare beneficiaries, were interviewed by telephone forinformation on usual occupation and other factors. We classified usualoccupation into one of four categories of physical activity. After excludingsubjects for whom a strength rating could not be assigned, we had a finalsample size of 4,863 cases and 6,783 controls. Using conditional logisticregression models, we calculated adjusted odds ratios (OR) and 95 percentconfidence intervals (CI) for occupations having light, medium, and heavyactivity compared with sedentary ones. Women with heavy-activity occupationshad a lower risk of breast cancer than women with sedentary jobs (OR = 0.82,CI = 0.63-1.08), as di d women with jobs with medium activity (OR = 0.86, CI= 0.77-0.97) or light activity (OR = 0.92, CI = 0.84-1.01). There was asignificant decreasing trend in the ORs from sedentary to heavy work (P =0.007). Although limited by exposure misclassification, these data areconsistent with the hypothesis that physical activity reduces the risk ofbreast cancer.     

Serum concentrations of organochlorine compounds and endometrial cancer risk (United States)

Objectives: Endogenous and exogenous estrogens are important in the development of endometrial cancer. Several organochlorine compounds, such as o,p-DDT, have estrogenic properties. The objective of this case-control analysis was to examine serum concentrations of organochlorine compounds and risk of endometrial cancer.Methods: Analyses were based on a sample of 90 endometrial cancer cases and 90 individually matched community controls from a multicenter case-control study in five geographic regions of the United States. Information on potential confounders, including menstrual and reproductive factors, cigarette smoking, diet, and weight, was obtained by interview.Results: The adjusted relative risk of endometrial cancer in the highest quartile of exposure compared with women in the lowest quartile was 0.7 (95 percent confidence interval [CI] = 0.2-2.0) for p,p-DDE, and 0.9 for total polychlorinated biphenyls (PCBs) (CI = 0.4-2.5).Conclusions: These findings do not support the hypothesis that organochlorine compounds are linked to the development of endometrial cancer.     

Prostate cancer screening (United States)

In 1995, there will be 244,000 new cases of prostate cancer, and 40,400 deaths from prostate cancer, among men in the United States. The American Cancer Society reports that the incidence rate of prostate cancer is increasing at an accelerated pace, and was 21 percent higher in 1994 than in 1993. The major reason for this steep rise is likely to be due to increased popularity of prostate cancer screening which, by identifying latent, asymptomatic cases, may convert them into clinical cases. Is screening—an important means of cancer control for many sites—a reasonable approach for prostate cancer control? The answer is not straightforward because prostate cancer is not one, but three diseases: a latent form which will cause no harm; a progressive form which will become symptomatic and can kill; and a rapidly progressive form so malignant that it is likely to kill, whether detected early or late. Screen-detection may be worthwhile only for the second form, as tumors of the first form need never be detected, and tumors of the third form progress so rapidly that timely screen-detection is nearly impossible and, if accomplished, may be valueless. As there is no way to differentiate among the three diseases when screening, the possible deleterious effects of screen-detection must be weighed against the benefits.Dr Waterbor is with the Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, AL, USA. Dr Bueschen is with the Division of Urology, Department of Surgery, School of Medicine, University of Alabama at Birmingham. Address correspondence to Dr Waterbor, University of Alabama at Birmingham, Department of Epidemiology, Tidwell Hall 201, 720 S 20th Street, Birmingham, AL 35924-0008, USA.     

Population-density and county-level variation in breast cancer mortality rates among white women residing in the Northeastern and Southern United States

OBJECTIVE: We assessed the contribution of variation in risk factor prevalence to population-density and county-level variation in breast cancer mortality rates. METHODS: In 1995 we collected risk factor information in a telephone interview of a random digit dialed sample of: (1) 1241 women from counties in the upper and lower tertiles of population density as of 1970 in the Northeast and South of the United States (Design A); (2) 2492 women from counties in the upper and lower tertiles of 1970-1979 breast cancer mortality rates in the four populations from Design A, and; (3) 276 women in Nassau County in New York State. We calculated 1990-94 mortality ratios (MRs) adjusted for breast cancer risk factors. RESULTS: The high/low population-density fully-adjusted MRs in women > or = 55 years were 1.01 (95% CI 0.9-1.2) and 1.00 (95% CI 0.8-1.2). The fully-adjusted MRs for high versus low mortality counties ranged from 0.95 (95% CI 0.8-1.2) to 1.29 (95% CI 1.0-1.6) in women > or = 55 years. CONCLUSIONS: Differences in risk factor prevalence explained higher rates in high-density versus low-density areas in older women. Modest elevations in the adjusted high/low breast cancer MRs among older women in certain groups of counties may reflect unidentified risk factors but more likely are due to chance.     

Dietary fats and lung cancer risk among women: the Missouri Women's Health Study (United States)

In a population-based case-control study of women in Missouri (United States), most of whom were smokers, we obtained information on adult diet to evaluate the effects of dietary fats in relation to lung cancer risk. All newly diagnosed, primary lung cancer cases among women 35 to 84 years of age reported to the Missouri Cancer Registry from 1 January 1993 to 31 January1994 were invited to participate, as were population-based controls. The analysis focused on interviews obtained from 624 controls and 587 cases. In-person interviews were obtained from 99.0 percent of controls and 60.6percent of cases. Age and energy-adjusted relative risks suggested a direct relation between risk of lung cancer and intake of dietary fats (e.g., total fat, saturated fat) and frequency of meat consumption. After adjusting for confounders, dietary fats were no longer associated with risk, but the adverse effect of frequent consumption of meat persisted. Risk was elevated about 90 percent (95 per cent confidence interval = 1.2-3.0) among women in the highest quintile of red meat intake compared with those in the lowest quintile. Risk estimates associated with red meat consumption, however, were dependent on interview status; the effect was restricted to cases whose dietary information was provided by proxy. In summary, after adjusting for potential confounders and removing data obtained from proxy respondents, dietary fats and consumption of red meat were not associated with lung cancer risk among women in Missouri. This revised version was published online in July 2006 with corrections to the Cover Date.     

A prospective study of oral contraceptive use and risk of breast cancer (Nurses' Health Study, United States)

Results of previous epidemiologic studies have provided reassurance that there is little, if any, increase in risk of breast cancer with oral contraceptive (OC) use in general. However, in several studies, an increased risk of breast cancer has been observed in two subgroups, young women who used OCs for extended durations and in women who used OCs prior to a first-term pregnancy. We evaluated these relationships using data from the ongoing Nurses' Health Study cohort (United States). We documented 3,383 cases of breast cancer from 1976 to 1992 among 1.6 million person-years of follow-up. We observed no overall relationship between duration of OC use and breast cancer risk, even among women who reported using OCs for 10 or more years (multivariate relative risk [RR]=1.11, 95 percent confidence interval [CI]=0.94-1.32). Among women less than 45 years of age, the multivariate RR for using OCs for 10 or more years was 1.07 (CI=0.70-1.65) compared with never-users. The risk associated with five or more years of OC use prior to a first full-term pregnancy compared with never-use was 0.96 (CI=0.65-1.43). Among women less than 45 years of age, we observed no evidence of an increased risk with OC use before a first full-term pregnancy (use for five or more years: RR=0.57, CI=0.24-1.31). Because of the age distribution of our cohort, we were unable to evaluate these relationships among women less than 40 years of age. Our study provides considerable evidence that long-term past OC use, either overall or prior to a first full-term pregnancy, does not result in any appreciable increase in breast cancer risk in women over 40 years of age.     

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.     

Physical activity and breast cancer risk in the College Alumni Health Study (United States)

Objectives: It is unclear whether physical activity is associated with a reduced risk of breast cancer. Some studies also suggest different effects between pre- and postmenopausal women, and lean and heavy women.Methods: We followed 1,566 University of Pennsylvania alumnae (mean age, 45.5 years), initially free of breast cancer, from 1962 until 1993. Physical activity at baseline was assessed by asking women about stairs climbed, blocks walked, and sports played. We estimated energy expenditure and categorized women into approximate thirds (< 500, 500-999, 1,000+ kcal/wk). We identified 109 breast cancer cases during 35,365 person-years from follow-up questionnaires or from death certificates.Results: After adjustment for age and body mass index (BMI) (kg/m2), the relative risk (RR) of breast cancer was 0.92 (95 percent confidence interval [CI]=0.58-1.45) among women expending 500-999 kcal/wk and 0.73 (CI=0.46-1.14) for those expending 1,000+ kcal/wk, compared with women expending < 500 kcal/wk (P trend=0.17). This association was modified by menopausal status, but not BMI. For postmenopausal women, corresponding RRs were 0.95 (CI=0.58-1.57) and 0.49 (CI=0.28-0.86), respectively (P trend=0.015). Increased physical activity in premenopausal women was not significantly associated with decreased risk of breast cancer.Conclusions: These data support an inverse association between physical activity and breast cancer among postmenopausal women. Cancer Causes and Control 1998, 9, 433–439     

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.     

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.     

Age at menarche, time to regular cycling, and breast cancer (North Carolina, United States)

Objectives: Later menarche, and a longer time until onset of regular cycling, are considered markers of lower lifetime exposure to circulating ovarian hormones. While later age at menarche is associated with reduced breast cancer risk, evidence for the relationship between time until onset of regular cycles and breast cancer is inconsistent. We evaluated both associations with breast cancer risk.Methods: We used data from the Carolina Breast Cancer Study, a population-based case-control study of breast cancer among White and Black women aged 20 to 74 years, residing in central and eastern North Carolina (United States). Cases were diagnosed between May 1993 and June 1996. Unconditional logistic regression models were limited to women with complete data for the risk factors considered (n = 830 cases, 758 controls).Results: We observed an inverse relationship between age at menarche and breast cancer risk, but found little support for the hypothesis that a longer time until onset of regular menstrual cycling was associated with reduced risk of breast cancer (odds ratios=1.0 [95 percent confidence interval (CI) = 0.7-1.5], and 1.2 [CI = 0.8-1.6], respectively, for 1-4 years and < 1 year until onset of regular cycling, relative to 5+ years). There was little relationship between age at menarche and time until regular cycling. We found strong evidence that delays in onset of regular cycling were associated with increased frequency of irregular cycles throughout young adulthood.Conclusions: Given the inconsistent findings regarding the links between menstrual cycle characteristics and breast cancer, and recent recommendations to delay menarche and alter the patterns of cycles of young women in order to reduce breast cancer risk, this topic calls for further, innovative study.     

Disparities in lung cancer stage, treatment and survival among American Indians and Alaskan Natives

Background

Disparities in lung cancer care and outcomes have been documented for blacks and Hispanics. Less is known about the care received by the American Indian and Alaskan Native population (AI/AN). We sought to evaluate lung cancer outcomes in this population and to asses if potential disparities in survival are explained by differences in stage of disease at diagnosis and type of treatment received.

Methods

We identified patients with potentially resectable (stages I-IIIA) non-small cell lung cancer (NSCLC) from the Surveillance, Epidemiology and End Results registry between 1988 and 2006. Kaplan-Meier curves were used to compare survival of AI/AN patients to those of other racial groups. Cox regression analysis was used to identify potential mediators of the association between AI/AN origin and worse survival.

Results

Five-year lung cancer survival was 47% for AI/AN, 56% for whites, 51% for blacks, 55% for Hispanics and 59% for individuals of other race (p < 0.0001). AI/AN were more likely to be diagnosed with stage IIIA (p < 0.0001) and less likely to undergo resection (p < 0.0001) than whites. In multivariable regression analyses, controlling for patient characteristics and histology, AI/AN race was associated with worse survival than white patients. When stage, treatment and surgery were added to the model, AI/AN origin was no longer significantly associated with worse outcomes.

Conclusions

AI/AN with potentially resectable NSCLC have survival rates comparable to other minority groups and worse than whites. These survival differences are partly explained by advanced stage at diagnosis, and lower rates of treatment.     

Induced and spontaneous abortion in relation to risk of breast cancer (United States)

The relation of induced and spontaneous abortion to the risk of breast cancer is evaluated in a hospital-based case-control interview study conducted in three cities in the United States from 1985 through 1995. Cases were 1,803 women aged 25 to 64 years with newly diagnosed invasive breast cancer; controls were 4,182 women of the same ages admitted for conditions unrelated to reproductive factors. Other breast cancer risk-factors were controlled through multiple logistic regression. The reference for allanalyses was women who had never had an abortion, either induced or spontaneous. Among parous women, the relative risk (RR) estimate was 1.1 (95percent confidence interval [CI] = 0.9-1.5) for induced abortion overall, 1.0(CI = 0.7-1.4) for abortion before the first birth, and 1.3 (CI = 1.0-1.8)for abortion after at least one birth. Among nulliparous women, the relative risk estimate for induced abortion was 1.3 (CI = 0.9-1.9). There was no trend of increased risk with number of abortions, nor was there consistent evidence of an increased risk in any particular subgroup. Spontaneous abortion was not associated with increased risk of breast cancer, either among nulliparous women or among parous women. These findings provide little support for the hypothesis that induced abortion increases breast cancer risk overall or in particular subgroups. This revised version was published online in July 2006 with corrections to the Cover Date.     

Risk-adjusted cancer-incidence rates (United States)

A risk-adjusted method is proposed for estimating cancer incidence rates from data collected by the Surveillance, Epidemiology, and End Results (SEER) program of the US National Cancer Institute. Unlike the conventional incidence-rate estimates reported by SEER, this method considers only the first primary cancer, and adjusts for population-based cancer prevalence, as well as for surgical procedures which remove an individual from risk of developing a given cancer. Thus, risk-adjusted incidence-rates more accurately reflect the average cancer risk for individuals in the cancer-free, at-risk population. The results of the analysis indicate that, in general, incidence-rate estimates are fairly similar between the conventional and risk-adjusted methods. However, this is not the case for certain cancer sites which may have: (i) a high number of subsequent primary cancers (e.g., melanomas—skin); (ii) a high cancer prevalence proportion (e.g., prostate cancer); (iii) a high number of subsequent primary cancers and prevalence proportion (e.g., female breast); or (iv) a high prevalence of removal of the organ in question (e.g., cervical and uterine cancers). For example, by applying the risk-adjusted incidence method for in situ and invasive cervical cancer, we found that in the period 1990–92 the age-adjusted incidence-rate estimate increased from 57.8 to 66.3 (15 percent) per 100,000 person-years; the greatest increase in the incidence-rate estimate occurred for women aged 65 to 69 years, from 40.1 to 63.2 (58 percent) per 100,000 person-years; and the lifetime risk of developing cervical cancer increased from 4.6 (1 in 22) to 5.5 (1 in 18) percent.Drs Merrill and Feuer are with the Cancer Control Research Program of the National Cancer Institute, Applied Research Branch, Bethesda, MD, USA. Address correspondence to Dr Merrill, US National Cancer Institute, Division of Cancer Prevention and Control, Applied Research Branch, 9000 Rockville Pike, EPN 313, Bethesda, MD 20892-7368, USA.     

Laryngeal cancer incidence among workers exposed to acid mists (United States)

In 1992, the International Agency for Research on Cancer (IARC) determined that sufficient evidence existed to classify sulfuric acid mists as a human carcinogen, based primarily on six human studies. Possible mechanisms include irritation of epithelial cells in conjunction with cigarette smoking, or a direct genotoxic effect due to a modification of cellular pH. We have followed 1,031 men exposed to acid mists in the steel industry in the United States, via mailed questionnaire and telephone interview, extending by 10 years a prior follow-up of this cohort. These workers averaged 9.2 years of exposure, with an average first year of exposure of 1949. The primary exposure was to sulfuric acid mist, although part of the cohort was exposed to other acid mists. Fourteen laryngeal cancers were observed in the cohort compared with 5.6 expected based on US rates, with follow-up through 1994. A 14 percent upward adjustment in expected cancers due to differences in tobacco and alcohol consumption led to 6.4 laryngeal cancers expected, yielding a rate ratio of 2.2 (95 percent confidence interval=1.2-3.7). Our findings are consistent with previous findings from this cohort and from most other studies, and tend to confirm IARC's classification of acid mists as a human carcinogen. The occupational exposures of this cohort were at least an order of magnitude higher than usual ambient exposures in urban air.     

Dietary relationships with early onset (under age 45) breast cancer in a case-control study in the United States: influence of chemotherapy treatment

Methodologic investigations have addressed selection and recall biasin case-control studies of diet and breast cancer, whereas the effect ofdisease progression and medical treatment on estimates of dietary intake hasbeen largely overlooked. In a multicenter, population-based case-controlstudy of breast cancer in the United States, 1,588 newly diagnosed cases and1,451 controls completed a self-administered food-frequency questionnaire.Initial evaluation suggested increased risk related to high intakes ofcalories, carbohydrates, fat, and protein. All nutrient associations werediminished after adjustment for calories. Evaluation by stage of diseaserevealed no relation of calories to risk among women with in situ disease,but elevated risks among women with localized (odds ratio [OR] = 1.33, 95percent confidence interval [CI] = 1.0-1.7 highest cf lowest quartile) orregional and distant disease (OR = 1.79, CI = 1.3-2.4). Further evaluationshowed that the increased risk a ssociated with calories was restricted tocases who reported having been treated with chemotherapy (OR = 1.66, CI =1.3-2.1). A gradient of increasing risk with time interval from diagnosis tointerview suggested the chemotherapy regimen itself and not necessarilycharacteristics of tumors requiring this treatment was responsible for theobserved increased risk. These results indicate that epidemiologic studies ofdiet and breast cancer, particularly among young women, should evaluatepossible bias related to post-diagnosis influences.