Linda Titus-Ernstoff

Environmental Endocrine Modulators and Human Health: An Assessment of the Biological Evidence

Recently, a great deal of attention and interest has been directed toward the hypothesis that exposure, particularly in utero exposure, to certain environmental chemicals might be capable of causing a spectrum of adverse effects as a result of endocrine modulation. In particular, the hypothesis has focused on the idea that certain organochlorine and other compounds acting as weak estrogens have the capability, either alone or in combination, to produce a variety of adverse effects, including breast, testicular and prostate cancer, adverse effects on male reproductive tract, endometriosis, fertility problems, alterations of sexual behavior, learning disability or delay, and adverse effects on immune and thyroid function. While hormones are potent modulators of biochemical and physiological function, the implication that exposure to environmental hormones (e.g., xenoestrogens) has this capability is uncertain. While it is reasonable to hypothesize that exposure to estrogen-like compounds, whatever their source, could adversely affect human health, biological plausibility alone is an insufficient basis for concluding that environmental endocrine modulators have adversely affected humans. Diethylstilbestrol (DES) is a potent, synthetic estrogen administered under a variety of dosing protocols to millions of women in the belief (now known to be mistaken) that it would prevent miscarriage. As a result of this use, substantial in utero exposure to large numbers of male and female offspring occurred. Numerous studies have been conducted on the health consequences of in utero DES exposure among the adult offspring of these women. There are also extensive animal data on the effects of DES and there is a high degree of concordance between effects observed in animals and humans. The extensive human data in DES-exposed cohorts provide a useful basis for assessing the biological plausibility that potential adverse effects might occur following in utero exposure to compounds identified as environmental estrogens. The effects observed in both animals and humans following in utero exposure to sufficient doses of DES are consistent with basic principles of dose response as well as the possibility of maternal dose levels below which potential non-cancer effects may not occur. Significant differences in estrogenic potency between DES and chemicals identified to date as environmental estrogens, as well as an even larger number of naturally occurring dietary phytoestrogens, must be taken into account when inferring potential effects from in utero exposure to any of these substances. The antiestrogenic properties of many of these same exogenous compounds might also diminish net estrogenic effects. Based on the extensive data on DES-exposed cohorts, it appears unlikely that in utero exposure to usual levels of environmental estrogenic substances, from whatever source, would be sufficient to produce many of the effects (i.e., endometriosis, adverse effects on the male reproductive tract, male and female fertility problems, alterations of sexual behavior, learning problems, immune system effects or thyroid effects) hypothesized as potentially resulting from exposure to chemicals identified to date as environmental estrogens.

Over-the-counter analgesics and risk of ovarian cancer

BACKGROUND Evidence that aspirin and other non-steroidal anti-inflammatory drugs reduce risk for colorectal cancer has prompted interest in their ability to prevent other cancers. We aimed to find out what effect over-the-counter analgesics have on risk of ovarian cancer. METHODS In a case-control study we compared use of over-the-counter analgesics by 563 women from eastern Massachusetts and New Hampshire, USA, who had epithelial ovarian cancer with 523 women from the general population. We calculated exposure odds ratios to estimate the effect of over-the-counter analgesics on ovarian cancer risk. Use of over-the-counter analgesics was assessed through interviews and defined as use at least once a week continuously for at least 6 months. FINDINGS The odds ratio for risk of ovarian cancer for aspirin use was 0.75 (95% CI 0.52-1.10), that for ibuprofen was 1.03 (0.64-1.64), and that for paracetamol was 0.52 (0.31-0.86), after adjusting for age, study centre, education, religion, parity, oral contraceptive use, and menstrual, arthritic, or headache pain. Relative to no use, the lower risk of ovarian cancer associated with paracetamol was more apparent for use on a daily basis, 0.39 (0.21-0.74), for more than 10 years of use, 0.40 (0.19-0.88), or for more than 20 tablet years defined as (tablets per day x years of use), 0.45 (0.20-0.99). INTERPRETATION In our data, there was a statistically significant inverse association between paracetamol use and ovarian cancer risk. There was a modest but non-significant inverse association with aspirin use and ovarian cancer and no association with ibuprofen use. Experimental studies in rodents demonstrating uterine and ovarian atrophy at high doses of paracetamol and decreased ovarian-cyst formation at lower doses suggest a biological basis for our observations.

Risk of breast cancer in women exposed to diethylstilbestrol in utero: preliminary results (United States)

BACKGROUND: A synthetic estrogen, diethylstilbestrol (DES), was widely prescribed to pregnant women during the 1950s and 1960s but was later discovered to be associated with an increased risk of clear-cell carcinoma of the vagina and cervix in female offspring. DES has not been linked to other cancers in female offspring, but studies of other prenatal factors such as twin gestation and pre-eclampsia have indicated that in-utero estrogen levels may influence breast cancer risk. We evaluated the relation of in-utero DES exposure to the risk of adult breast cancer.METHODS: A cohort of 4821 exposed women and 2095 unexposed women, most of whom were first identified in the mid-1970s, were followed by mailed questionnaires for an average of 19 years. Reported cancer outcomes were validated by medical record review. Breast cancer incidence in DES-exposed daughters was compared with cancer incidence in unexposed daughters with use of Poisson regression analysis, adjusting for year of birth, age at menarche, age at first birth, and number of births.FINDINGS: The rate ratio for incidence of invasive breast cancer in exposed versus unexposed women was 1.4 (95% confidence interval (CI) = 0.7–2.6). DES exposure was not associated with an increased risk of breast cancer in women under 40 years, but among women aged 40 and older the rate ratio was 2.5 (95% CI = 1.0–6.3). The rate ratio for the association of DES exposure with estrogen receptor-positive tumors was 1.9 (95% CI = 0.8–4.5).INTERPRETATION: While not statistically significant, the overall 40% excess risk, arising exclusively from the subset of estrogen receptor-positive cases, raises a concern calling for continued investigation.

Weight change and risk of postmenopausal breast cancer (United States)

AbstractObjective: Although many studies have shown that higher weight increases the risk of postmenopausal breast cancer, some aspects of this association are unclear. In order to examine the risk associated with different patterns of weight change, we analyzed data from a large case–control study of postmenopausal breast cancer. Methods: Participants included women aged 50–79 years (n = 5031) who are newly diagnosed with invasive breast cancer in Massachusetts, New Hampshire, and Wisconsin. Similarly-aged population controls (n = 5255) were selected at random from drivers license files and Medicare beneficiary lists. Height, weight, and information on other breast cancer risk factors were ascertained by structured telephone interviews from 1992 to 1995, and logistic regression was used to estimate multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI). Results: Women in the top quintile groups for height at age 20, recent weight, and recent body mass index had significantly increased risks of breast cancer. Among women who reached their highest adult weight at younger ages (≤45 years), increasing weight loss since that age was associated with a reduced risk of postmenopausal breast cancer (OR 0.90, CI 0.84–0.98, per 5 kg). However, weight loss among women whose highest weight occurred after age 45 was not associated with risk (OR 1.00, CI 0.95–1.05, per 5 kg). Weight gain since the lowest adult weight increased risk by 8% for each 5 kg of gain (OR 1.08, CI 1.06–1.11). Temporary weight cycling (weight loss followed by weight gain) was not associated with increased risk. Conclusions: Weight gain clearly increased risk of postmenopausal breast cancer. These data lend further support to efforts aimed at helping women avoid weight gain as they age.

Population based study of coffee, alcohol and tobacco use and risk of ovarian cancer

Coffee, alcohol and tobacco use have been examined in many epidemiologic studies of ovarian cancer but findings have generally been inconclusive. To explain prior inconsistent findings, we sought to determine whether associations with these exposures might vary by histologic subtype of ovarian cancer or menopausal status at diagnosis. We conducted a population‐based case‐control study in eastern Massachusetts and New Hampshire involving 549 women with newly‐diagnosed epithelial ovarian cancer and 516 control women selected either by random digit dialing or through lists of residents. Coffee and alcohol consumption was assessed through a semi‐quantitative food‐frequency questionnaire, and information on tobacco smoking was collected through personal interview. Consumption of coffee and caffeine was associated with increased risk for ovarian cancer but only among premenopausal women. There was no increase in risk for ovarian cancer overall associated with tobacco or alcohol use in either pre‐ or post‐menopausal women. Association of borderline significance for tobacco and invasive serous cancers and alcohol and mucinous cancers were observed but reduced after adjustment for coffee consumption. We conclude that coffee and caffeine consumption may increase risk for ovarian cancer among premenopausal women and are findings that have some epidemiologic and biologic support. Int. J. Cancer 88:313–318, 2000.

Carotenoids, antioxidants and ovarian cancer risk in pre- and postmenopausal women.

An inverse association between ovarian cancer risk, carotenoids and antioxidant vitamins has been suggested by several epidemiologic studies and 1 experimental trial of a vitamin A analogue. From a population‐based study of 549 cases of ovarian cancer and 516 controls, we estimated the consumption of the antioxidant vitamins A, C, D and E and various carotenoids, including alpha‐ and beta‐carotene and lycopene, using a validated dietary questionnaire. Multivariate logistic regression was used to calculate the exposure odds ratios adjusted for established ovarian cancer risk factors. Intakes of carotene, especially alpha‐carotene, from food and supplements were significantly and inversely associated with risk for ovarian cancer, predominantly in postmenopausal women. Intake of lycopene was significantly and inversely associated with risk for ovarian cancer, predominantly in premenopausal women. Food items most strongly related to decreased risk for ovarian cancer were raw carrots and tomato sauce. Consumption of fruits, vegetables and food items high in carotene and lycopene may reduce the risk of ovarian cancer.

Long-term cancer risk in women given diethylstilbestrol (DES) during pregnancy.

From 1940 through the 1960s, diethylstilbestrol (DES), a synthetic oestrogen, was given to pregnant women to prevent pregnancy complications and losses. Subsequent studies showed increased risks of reproductive tract abnormalities, particularly vaginal adenocarcinoma, in exposed daughters. An increased risk of breast cancer in the DES-exposed mothers was also found in some studies. In this report, we present further follow-up and a combined analysis of two cohorts of women who were exposed to DES during pregnancy. The purpose of our study was to evaluate maternal DES exposure in relation to risk of cancer, particularly tumours with a hormonal aetiology. DES exposure status was determined by a review of medical records of the Mothers Study cohort or clinical trial records of the Dieckmann Study. Poisson regression analyses were used to estimate relative risks (RR) and 95% confidence intervals (CI) for the relationship between DES and cancer occurrence. The study results demonstrated a modest association between DES exposure and breast cancer risk, RR = 1.27 (95% CI = 1.07–1.52). The increased risk was not exacerbated by a family history of breast cancer, or by use of oral contraceptives or hormone replacement therapy. We found no evidence that DES was associated with risk of ovarian, endometrial or other cancer.

Genital talc exposure and risk of ovarian cancer

Epidemiologic studies have suggested an increased risk for ovarian cancer associated with the use of talcum powder in genital hygiene, but the biologic credibility of the association has been questioned. We conducted a population‐based case‐control study in eastern Massachusetts and New Hampshire involving 563 women with newly diagnosed epithelial ovarian cancer and 523 control women selected either by random digit dialing or through lists of residents. Use of body powders was assessed through personal interview and the exposure odds ratio (OR) for the use of talc in genital hygiene was calculated. Cases were more likely than controls (45% vs. 36%) to have used talc as a body powder in some manner, and the excess was confined to patients who used talc on the perineum directly or as a dusting powder to underwear or sanitary napkins. Relative to women who never used body powder or used it only in non‐genital areas, the OR (and 95% confidence interval) associated with genital exposure to talc was 1.60 (1.18 and 2.15) after adjustment for age, study location, parity, oral contraceptive use, body mass index and family history of breast or ovarian cancer. Exposure prior to rather than after a first livebirth appeared to be more harmful, and the association was most apparent for women with invasive serous cancers and least apparent for those with mucinous tumors. We conclude that there is a significant association between the use of talc in genital hygiene and risk of epithelial ovarian cancer that, when viewed in perspective of published data on this association, warrants more formal public health warnings. Int. J. Cancer 81:351–356, 1999.

Flavonoid intake and ovarian cancer risk in a population-based case-control study

Several recent studies have evaluated the association between dietary flavonoid intake and ovarian cancer risk, and all reported significant or suggestive inverse associations with certain flavonoids or flavonoid subclasses; however, most of these studies were small to moderate in size. We, therefore, examined this association in a large, population‐based case‐control study. We calculated intake of 5 common dietary flavonoids (myricetin, kaempferol, quercetin, luteolin, and apigenin), as well as total intake of these flavonoids, for 1,141 cases and 1,183 frequency‐matched controls. We used unconditional logistic regression to estimate the relative risk (RR) of ovarian cancer for each quintile of flavonoid intake when compared with the lowest quintile. We did not observe an association between total flavonoid intake and ovarian cancer risk. The multivariable‐adjusted RR for the highest versus lowest quintile of total flavonoid intake was 1.06 (95% confidence interval [CI] = 0.78–1.45). In analyses of each individual flavonoid, only intake of apigenin was associated with a borderline significant decrease in risk (RR, highest vs. lowest quintile = 0.79, 95% CI = 0.59–1.06; p‐trend = 0.26), and this association was significant after adjustment for intake of the other 4 individual flavonoids (comparable RR = 0.72, 95% CI = 0.53–0.98; p‐trend = 0.09). These results provide limited support for an association between flavonoid intake and ovarian cancer risk. However, given the findings of previous studies and the biologic plausibility of this association, additional studies are warranted.

Incidence of squamous neoplasia of the cervix and vagina in women exposed prenatally to diethylstilbestrol (United States)

AbstractObjectives: Women exposed prenatally to diethylstibestrol (DES) have an excess risk of clear-cell adenocarcinoma of the vagina and cervix, but the effect on the incidence of squamous neoplasia is uncertain. The purpose of the current study was to evaluate the long-term risk of developing high-grade squamous neoplasia of the genital tract among women exposed prenatally to DES. Methods: A cohort comprising 3899 DES-exposed and 1374 unexposed daughters was followed for 13 years (1982–1995) for pathology-confirmed diagnoses of high-grade squamous intraepithelial neoplasia (HSIL) of the genital tract. Poisson regression analysis was used to compute relative risks (RR) and 95% confidence intervals (95% CI), adjusting for age, calendar year, and other covariates. Results: The RR (95% CI) among DES-exposed versus unexposed, based on 111 cases of high-grade disease, was 2.1 (1.2–3.8). Adjustment for screening history estimated by the number of years since the last Pap smear had little effect. Risk estimates were higher with earlier intrauterine exposure; the RR (95% CI) for exposure within 7 weeks of the last menstrual period was 2.8 (1.4–5.5). Only two cases of invasive squamous cervical cancer occurred in total, precluding separate analysis. Conclusions: The findings support an association between in-utero DES exposure and high-grade squamous neoplasia, although a role for more intensive screening among DES-exposed women in the production of this excess could not be completely ruled out.