Incidence rates and risks of diethylstilbestrol-related clear-cell adenocarcinoma of the vagina and cervix: Update after 40-year follow-up.

OBJECTIVE: Women exposed to diethylstilbestrol (DES) in utero are at increased risk for the development of vaginal and cervical clear cell adenocarcinoma (CCA) at younger age. It is unknown if a second peak will occur in later life, the ages when CCA developed spontaneously in the pre-DES era. The complete epidemiologic curve of CCA has not been reported, yet. METHODS: We reviewed 720 cases of CCA from the CCA registry at the University of Chicago through 2014. Incidence rates and cumulative risks for CCA were calculated based on white women born in the U.S. from 1948 through 1971. RESULTS: In 420 CCA cases there was documented evidence of prenatal DES exposure. 80% were among those between ages 15 and 31 but some occurred as late as age 55. A small second peak occurred around age 42. The risk of DES-related CCA was highest in the 1951-1956 birth cohort and this birth cohort effect closely correlated with DES prescriptions over time in the U.S. (r=0.98, P=0.005). By age 50, the cumulative risk of CCA was 1 per 750 exposed women. CCA cases without evidence of DES exposure had similar ages, year of diagnosis, and birth cohort patterns as the documented DES-exposed cases, suggesting that some negative cases were exposed. Their inclusion raises the cumulative risk of CCA to 1 per 520. CONCLUSION: With the largest data available, our results confirmed the association between prenatal DES exposure and clear cell adenocarcinoma. The study also refines the risks of DES-related CCA.

Prenatal diethylstilbestrol exposure and high-grade squamous cell neoplasia of the lower genital tract.

BACKGROUND: Prenatal diethylstilbestrol (DES) exposure is associated with an excess risk of clear-cell adenocarcinoma of the vagina and cervix, and of high-grade squamous neoplasia. OBJECTIVE: We explored whether neoplasia risk remains elevated among DES-exposed women as they age. STUDY DESIGN: In all, 4062 DES-exposed and 1837 unexposed daughters were followed for approximately 30 years (1982 through 2013) for pathology-confirmed diagnoses of cervical intraepithelial neoplasia grade ≥2 (CIN2+) of the lower genital tract (n = 178). Hazard ratios (HR) and 95% confidence intervals (CI) were estimated adjusting for birth year and individual study cohort. RESULTS: The cumulative incidence of CIN2+ in the DES-exposed group was 5.3% (95% CI, 4.1-6.5%) and in the unexposed group was 2.6% (95% CI, 1.5-3.7%). The HR for DES and CIN2+ was 1.98 (95% CI, 1.33-2.94), and was similar with further adjustment for frequency of cervical cancer screening (HR, 1.97; 95% CI, 1.33-2.93). The HR was 2.10 (95% CI, 1.41-3.13) with additional adjustment for other potential confounders. The HR for DES exposure was elevated through age 44 years (age <45 years HR, 2.47; 95% CI, 1.55-3.94), but not in women age ≥45 years (HR, 0.91; 95% CI, 0.39-2.10). In exposed women, HRs for DES were 1.74 (95% CI, 1.09-2.79) among those who had earlier evidence of vaginal epithelial changes (VEC), presumably reflecting glandular epithelium undergoing transformation to normal, adult-type squamous epithelium, and 1.24 (95% CI, 0.75-2.06) among those without VEC, compared with unexposed women. The HRs for DES and CIN2+ were higher among women with earlier intrauterine exposure (HR, 2.64; 95% CI, 1.64-4.25 for <8 weeks' gestation and HR, 1.41; 0.88-2.25 for ≥8 weeks' gestation), and lowest when exposure began >15th week (HR, 1.14; 95% CI, 0.59-2.20). CONCLUSION: CIN2+ incidence was higher among the DES exposed, particularly those with early gestational exposure and VEC. The HR for DES and CIN2+ remained positive and significant until the mid-40s, confirming that the recommendation of annual cytological screening among these women is appropriate. Whether those ≥45 years of age continue to require increased screening is unclear, and would require a careful weighing of possible risks and benefits.

Adverse health outcomes in women exposed in utero to diethylstilbestrol.

BACKGROUND: Before 1971, several million women were exposed in utero to diethylstilbestrol (DES) given to their mothers to prevent pregnancy complications. Several adverse outcomes have been linked to such exposure, but their cumulative effects are not well understood. METHODS: We combined data from three studies initiated in the 1970s with continued long-term follow-up of 4653 women exposed in utero to DES and 1927 unexposed controls. We assessed the risks of 12 adverse outcomes linked to DES exposure, including cumulative risks to 45 years of age for reproductive outcomes and to 55 years of age for other outcomes, and their relationships to the baseline presence or absence of vaginal epithelial changes, which are correlated with a higher dose of, and earlier exposure to, DES in utero. RESULTS: Cumulative risks in women exposed to DES, as compared with those not exposed, were as follows: for infertility, 33.3% vs. 15.5% (hazard ratio, 2.37; 95% confidence interval [CI], 2.05 to 2.75); spontaneous abortion, 50.3% vs. 38.6% (hazard ratio, 1.64; 95% CI, 1.42 to 1.88); preterm delivery, 53.3% vs. 17.8% (hazard ratio, 4.68; 95% CI, 3.74 to 5.86); loss of second-trimester pregnancy, 16.4% vs. 1.7% (hazard ratio, 3.77; 95% CI, 2.56 to 5.54); ectopic pregnancy, 14.6% vs. 2.9% (hazard ratio, 3.72; 95% CI, 2.58 to 5.38); preeclampsia, 26.4% vs. 13.7% (hazard ratio 1.42; 95% CI, 1.07 to 1.89); stillbirth, 8.9% vs. 2.6% (hazard ratio, 2.45; 95% CI, 1.33 to 4.54); early menopause, 5.1% vs. 1.7% (hazard ratio, 2.35; 95% CI, 1.67 to 3.31); grade 2 or higher cervical intraepithelial neoplasia, 6.9% vs. 3.4% (hazard ratio, 2.28; 95% CI, 1.59 to 3.27); and breast cancer at 40 years of age or older, 3.9% vs. 2.2% (hazard ratio, 1.82; 95% CI, 1.04 to 3.18). For most outcomes, the risks among exposed women were higher for those with vaginal epithelial changes than for those without such changes. CONCLUSIONS: In utero exposure of women to DES is associated with a high lifetime risk of a broad spectrum of adverse health outcomes. (Funded by the National Cancer Institute.).

Medical conditions among adult offspring prenatally exposed to diethylstilbestrol.

BACKGROUND: Diethylstilbestrol (DES), a synthetic estrogen that was used in pregnancy, is a prototype endocrine-disrupting chemical. Although prenatal exposure to DES is known to increase risks of vaginal/cervical adenocarcinoma and adverse reproductive outcomes in women, and urogenital anomalies in men, data on nonreproductive medical conditions are lacking. METHODS: We estimated hazard ratios and their associated 95% confidence intervals for the associations between prenatal DES exposure and the occurrence of cardiovascular disease, diabetes, osteoporosis, and related conditions among 5590 female and 2657 male offspring followed from 1994 through 2006, adjusted for birth year, cohort, sex, body mass index, smoking status, alcohol use, education, and number of general physical examinations in the past 5 years. RESULTS: Comparing persons exposed prenatally to DES with those who were not exposed, the hazard ratios were 1.21 (95% confidence interval = 0.96-1.54) for diabetes, 1.27 (1.00-1.62) for all cardiovascular disease, 1.18 (0.88-1.59) for coronary artery disease, 1.28 (0.88-1.86) for myocardial infarction, 1.12 (1.02-1.22) for high cholesterol, 1.14 (1.02-1.28) for hypertension, 1.24 (0.99-1.54) for osteoporosis, and 1.30 (0.95-1.79) for fractures. The associations did not differ by dose and timing of DES exposure, nor, in the women, by the presence or absence of vaginal epithelial changes (a marker of DES host susceptibility). CONCLUSIONS: These data raise the possibility that prenatal exposure to DES is associated with several common medical conditions in adulthood, although differential reporting by DES status and residual confounding cannot be ruled out. Further follow-up should assess these findings with validated outcomes and seek to understand the biological mechanisms.

Urogenital abnormalities in men exposed to diethylstilbestrol in utero: a cohort study.

BACKGROUND: Diethylstilbestrol (DES), a synthetic estrogen widely prescribed to pregnant women during the 1940s70s, has been shown to cause reproductive problems in the daughters. Studies of prenatally-exposed males have yielded conflicting results. METHODS: In data from a collaborative follow-up of three U.S. cohorts of DES-exposed sons, we examined the relation of prenatal DES exposure to occurrence of male urogenital abnormalities. Exposure status was determined through review of prenatal records. Mailed questionnaires (1994, 1997, 2001) asked about specified abnormalities of the urogenital tract. Risk ratios (RR) were estimated by Cox regression with constant time at risk and control for year of birth. RESULTS: Prenatal DES exposure was not associated with varicocele, structural abnormalities of the penis, urethral stenosis, benign prostatic hypertrophy, or inflammation/infection of the prostate, urethra, or epididymus. However, RRs were 1.9 (95% confidence interval 1.13.4) for cryptorchidism, 2.5 (1.54.3) for epididymal cyst, and 2.4 (1.54.4) for testicular inflammation/infection. Stronger associations were observed for DES exposure that began before the 11th week of pregnancy: RRs were 2.9 (1.65.2) for cryptorchidism, 3.5 (2.06.0) for epididymal cyst, and 3.0 (1.75.4) for inflammation/infection of testes. CONCLUSION: These results indicate that prenatal exposure to DES increases risk of male urogenital abnormalities and that the association is strongest for exposure that occurs early in gestation. The findings support the hypothesis that endocrine disrupting chemicals may be a cause of the increased prevalence of cryptorchidism that has been seen in recent years.

Reproductive and hormone-related outcomes in women whose mothers were exposed in utero to diethylstilbestrol (DES): A report from the US National Cancer Institute DES Third Generation Study.

BACKGROUND: Animal studies suggest that prenatal exposure to diethylstilbestrol (DES) causes epigenetic alterations in primordial germ cells that affect the next generation, but human studies are sparse. METHODS: We assessed hormonally mediated outcomes in third generation women whose mothers were prenatally DES-exposed and unexposed. RESULTS: Compared to the unexposed, DES-exposed third generation women had an increased risk of irregular menses and amenorrhea; the respective prevalence ratios and 95% confidence intervals (CI) in follow-up data were 1.32 (95% CI: 1.10, 1.60) and 1.26 (95% CI: 1.06, 1.49); associations were more apparent in third generation women whose prenatally DES-exposed mothers were affected by vaginal epithelial changes. The follow-up data also indicated an association with preterm delivery (relative risk (RR): 1.54; 95% CI: 1.35, 1.75). CONCLUSION: DES third generation women may have an increased risk of irregular menstrual cycles, amenorrhea, and preterm delivery, consistent with inter-generational effects of endocrine disrupting chemical exposure in humans.

Cervical screening and general physical examination behaviors of women exposed in utero to diethylstilbestrol.

OBJECTIVE: To estimate whether women exposed in utero to diethylstilbestrol (DES) report receiving more cervical and general physical examinations compared to unexposed women. MATERIALS AND METHODS: 1994 Diethylstilbestrol Adenosis cohort data are used to assess the degree of recommended compliance of cervical screenings found in 3,140 DES-exposed and 826 unexposed women. Participants were enrolled at 4 sites: Houston, Boston, Rochester, and Los Angeles. Logistic regression modeling was used to analyze mailed questionnaire data, which included reported frequency over the preceding 5 years (1990-1994) of Papanicolaou smears and general physical examinations. RESULTS: Diethylstilbestrol-exposed women exceeded the recommended frequency of Papanicolaou smear screenings [adjusted odds ratio (aOR) = 2.15, 95% CI (confidence interval) = 1.60-2.88] compared to the unexposed. This association held among those without a history of cervical intraepithelial neoplasia (aOR = 1.88, 95% CI = 1.35-2.62). Diethylstilbestrol-exposed women exceeded annual recommendations for physical examinations (aOR = 2.27, 95% CI = 1.16-4.43) among women without a history of chronic disease when compared to unexposed women. CONCLUSIONS: Most DES-exposed women are receiving cervical cancer screening at least at recommended intervals, but one third of the women are not receiving annual Papanicolaou smear examinations.

Secondary sex ratio among women exposed to diethylstilbestrol in utero.

BACKGROUND: Diethylstilbestrol (DES), a synthetic estrogen widely prescribed to pregnant women during the mid-1900s, is a potent endocrine disruptor. Previous studies have suggested an association between endocrine-disrupting compounds and secondary sex ratio. METHODS: Data were provided by women participating in the National Cancer Institute (NCI) DES Combined Cohort Study. We used generalized estimating equations to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the relation of in utero DES exposure to sex ratio (proportion of male births). Models were adjusted for maternal age, child's birth year, parity, and cohort, and accounted for clustering among women with multiple pregnancies. RESULTS: The OR for having a male birth comparing DES-exposed to unexposed women was 1.05 (95% CI, 0.95-1.17). For exposed women with complete data on cumulative DES dose and timing (33%), those first exposed to DES earlier in gestation and to higher doses had the highest odds of having a male birth. The ORs were 0.91 (95% C, 0.65-1.27) for first exposure at > or = 13 weeks gestation to < 5 g DES; 0.95 (95% CI, 0.71-1.27) for first exposure at > or = 13 weeks to > or = 5 g; 1.16 (95% CI, 0.96-1.41) for first exposure at < 13 weeks to < 5 g; and 1.24 (95% CI, 1.04-1.48) for first exposure at < 13 weeks to > or = 5 g compared with no exposure. Results did not vary appreciably by maternal age, parity, cohort, or infertility history. CONCLUSIONS: Overall, no association was observed between in utero DES exposure and secondary sex ratio, but a significant increase in the proportion of male births was found among women first exposed to DES earlier in gestation and to a higher cumulative dose.

Preeclampsia risk in women exposed in utero to diethylstilbestrol.

OBJECTIVE: To assess whether preeclampsia risk is elevated in pregnancies of diethylstilbestrol (DES)-exposed daughters. METHODS: This study used data from the National Cancer Institute DES Combined Cohorts Follow-up Study. A total of 285 preeclampsia cases (210 exposed and 75 unexposed) occurred in 7,313 live births (4,759 DES exposed and 2,554 unexposed). Poisson regression analysis estimated relative risks and 95% confidence intervals (CI) for preeclampsia adjusted for age at the index pregnancy, parity, education, smoking, body mass index, year of diagnosis, and cohort. RESULTS: In utero DES exposure was associated with nearly a 50% elevation in preeclampsia risk. Adjustment for preeclampsia risk factors attenuated the relative risk slightly (1.42, 95% CI 1.04-1.94). The excess risk with DES was concentrated among women who developed preeclampsia in their first pregnancies (relative risk 1.81, 95% CI 1.17-2.79), who were exposed before 15 weeks of gestation (relative risk 1.57, 95% CI 1.11-2.23), and who were treated with magnesium sulfate (relative risk 2.10, 95% CI 0.82-5.42). Among DES-exposed women who had a prior hysterosalpingogram, preeclampsia prevalence was higher in those with uterine abnormalities (12.4%) than in those without (7.7%). CONCLUSION: These data suggest that in utero exposure to DES is associated with a slightly elevated risk of preeclampsia, and that one possible biological mechanism involves uterine abnormalities.

Prenatal diethylstilbestrol exposure and risk of breast cancer.

It has been hypothesized that breast cancer risk is influenced by prenatal hormone levels. Diethylstilbestrol (DES), a synthetic estrogen, was widely used by pregnant women in the 1950s and 1960s. Women who took the drug have an increased risk of breast cancer, but whether risk is also increased in the daughters who were exposed in utero is less clear. We assessed the relation of prenatal DES exposure to risk of breast cancer in a cohort of DES-exposed and unexposed women followed since the 1970s by mailed questionnaires. Eighty percent of both exposed and unexposed women completed the most recent questionnaire. Self-reports of breast cancer were confirmed by pathology reports. Cox proportional hazards regression was used to compute incidence rate ratios (IRR) for prenatal DES exposure relative to no exposure. During follow-up, 102 incident cases of invasive breast cancer occurred, with 76 among DES-exposed women (98,591 person-years) and 26 among unexposed women (35,046 person-years). The overall age-adjusted IRR was 1.40 [95% confidence interval (95% CI), 0.89-2.22]. For breast cancer occurring at ages >or=40 years, the IRR was 1.91 (95% CI, 1.09-3.33) and for cancers occurring at ages >or=50 years, it was 3.00 (95% CI, 1.01-8.98). Control for calendar year, parity, age at first birth, and other factors did not alter the results. These results, from the first prospective study on the subject, suggest that women with prenatal exposure to DES have an increased risk of breast cancer after age 40 years. The findings support the hypothesis that prenatal hormone levels influence breast cancer risk.

Menstrual and reproductive characteristics of women whose mothers were exposed in utero to diethylstilbestrol (DES).

BACKGROUND: In women, prenatal exposure to diethylstilbestrol (DES) is associated with adult reproductive dysfunction. The mouse model, which replicates many DES outcomes, suggests DES causes epigenetic alterations, which are transmissable to daughters of prenatally exposed animals. We report menstrual and reproductive characteristics in a unique cohort comprising daughters of women exposed prenatally to DES. METHODS: Menstrual and reproductive outcomes and baseline characteristics were assessed by mailed questionnaire in 793 women whose mothers had documented information regarding in utero DES exposure. RESULTS: Mean age at menarche was 12.6 years in both groups, but daughters of the exposed women attained menstrual regularization later (mean age of 16.2 years vs. 15.8 years; P = 0.05), and were more likely to report irregular menstrual periods, odds ratio (OR) = 1.54 [95% confidence interval (95% CI 1.02-2.32)]. A possible association between mothers' DES exposure and daughters' infertility was compatible with chance, age, and cohort adjusted OR = 2.19 (95% CI 0.95-5.07). We found limited evidence that daughters of the exposed had more adverse reproductive outcomes, but daughters of exposed women had fewer live births (1.6) than the unexposed (1.9) (P = 0.005). CONCLUSIONS: The high risk of reproductive dysfunction seen in women exposed to DES in utero was not observed in their daughters, but most women in our cohort have not yet attempted to start their families, and further follow-up is needed to assess their reproductive health. Our findings of menstrual irregularity and possible infertility in third-generation women are preliminary but compatible with speculation regarding transgenerational transmission of DES-related epigenetic alterations in humans.

Risk of benign gynecologic tumors in relation to prenatal diethylstilbestrol exposure.

OBJECTIVE: To investigate the association between prenatal diethylstilbestrol (DES) exposure and risk of benign gynecologic tumors. METHODS: We conducted a collaborative follow-up study of women with and without documented intrauterine exposure to DES. We compared the incidence of self-reported ovarian cysts, paraovarian cysts, and uterine leiomyomata confirmed by medical record in DES-exposed and unexposed women. RESULTS: A total of 85 cases of uterine leiomyomata and 168 cases of ovarian or paraovarian cysts were confirmed histologically. After adjustment for age, no association was found between prenatal DES exposure and ovarian cysts or uterine leiomyomata. Prenatal DES exposure was positively associated with paraovarian cysts. CONCLUSION: The present results do not support the hypothesis that prenatal DES exposure increases risk of uterine leiomyomata or ovarian cysts. Prenatal DES exposure was associated with an increased risk of paraovarian cysts, but detection bias cannot be ruled out as an explanation of this finding.

Factors associated with a lack of pap smear utilization in women exposed in utero to diethylstilbestrol.

BACKGROUND: Women in the 1940s-1960s were prescribed diethylstilbestrol (DES), a nonsteroidal estrogen, to prevent miscarriages, but the practice was terminated after it was discovered that the daughters so exposed in utero were at increased risk for developing clear cell adenocarcinoma (CCA) of the vagina or cervix at early ages. Pap smear screening is one of the principal methods used to identify tumor development and is necessary in this group of women to maintain their health. Currently, little is known about the factors associated with nonutilization of this screening tool in this high-risk population of women. METHODS: National cohort data from the National Cancer Institute (NCI) DES Combined Cohort Follow-up Study during 1994, 1997, 2001, and 2006 were used to determine which factors were associated with Pap smear screening nonutilization in 2006 among DES-exposed and unexposed women. Self-reported questionnaire data from 2,861 DES-exposed and 1,027 unexposed women were analyzed using binary logistic regression models. RESULTS: DES exposure, not having a previous gynecologic dysplasia diagnosis, lack of insurance, originating cohort, increasing age, and previous screening behavior were all factors associated with not reporting a Pap smear examination in the 2006 questionnaire, although college education reduced nonutilization. CONCLUSIONS: Understanding which factors are associated with not acquiring a screening exam can help clinicians better identify which DES-exposed women are at risk for nonutilization and possibly tailor their standard of care to aid in the early detection of cervical and vaginal adenocarcinomas in this high-risk group.

Mammography screening behaviors of women exposed prenatally to diethylstilbestrol.

BACKGROUND: In utero diethylstilbestrol (DES) exposure is a risk factor for rare development of vaginal and cervical cancer and may potentially be a risk factor for breast cancer. Mammography use in this population is relatively unknown; therefore, this study aims to determine if in utero DES exposure is associated with the frequency of mammography screening examinations while considering demographic and clinical factors. METHODS: Using combined DES cohort questionnaire data, self-reported mammography screening over the past 5 years (2001-2006) was analyzed in women aged ≥45 years. Binary logistic regression assessed if DES exposure was associated with mammography use after adjustment for benign breast disease (BBD), previous cancer diagnosis, and whether insurance access influenced screening use. RESULTS: Overall, the frequency of mammography examinations was similar for both DES-exposed and unexposed women. DES-exposed (n=2986) and unexposed women (n=1397) over the age of 44 reported receiving ≥3 mammography examinations in the past 5 years (73.8% and 74.0%, respectively). After adjustment, DES exposure was not associated with ≥3 mammograms in the past 5 years compared to ≤2 examinations (odds ratio [OR] 1.00, 95% confidence interval [CI] 0.86-1.17), p=0.99). CONCLUSIONS: In utero DES exposure was not associated with mammography use, nor was health insurance status or a BBD or cancer diagnosis. Because of the potential elevated risk for breast cancer in women exposed prenatally to DES, continued monitoring of standard mammography recommendations is recommended for this group, which is predominantly over the age of 45.

Breast cancer screening in women exposed in utero to diethylstilbestrol.

PURPOSE: To determine if women exposed in utero to diethylstilbestrol (DES) are more likely than unexposed women to receive recommended or additional breast cancer screening examinations. METHODS: 1994 Diethylstilbestrol-Adenosis (DESAD) cohort data are used to assess the degree of recommended compliance of breast cancer screenings found in 3140 DES-exposed and 826 unexposed women. Participants were enrolled at four sites: Houston, Boston, Rochester, and Los Angeles. Logistic regression modeling was used to analyze mailed questionnaire data that included reported frequency over the preceding 5 years (1990-1994) of breast-self examinations (BSEs), clinical breast examinations (CBEs), and mammograms. RESULTS: DES-exposed women exceeded annual recommendations for CBEs (aOR 2.20, 95% CI, 1.04-4.67) among women without a history of benign breast disease (BBD) compared with unexposed women. There were no other statistically significant differences between exposed and unexposed women who reported performing BSEs, CBEs (<40 years of age), and mammographies, regardless of BBD history. CONCLUSIONS: The majority of DES-exposed women receive breast cancer screenings at least at recommended intervals, but over two thirds do not perform monthly BSEs. Future efforts should be focused on further educating this and other at-risk populations through mailed reminders and during patient consultations on the benefits of screening examinations.

Offspring of women exposed in utero to diethylstilbestrol (DES): a preliminary report of benign and malignant pathology in the third generation.

BACKGROUND: Animal studies suggest that prenatal exposure to the synthetic estrogen diethylstilbestrol (DES) causes epigenetic changes that may be transmitted to the next generation. Specifically, these studies show an elevated incidence of reproductive tumors in the female offspring of prenatally-exposed mice. METHODS: We assessed cancer and benign pathology diagnoses occurring in the offspring of women whose prenatal exposure to DES (or lack of exposure) was verified by medical record. Our data arose from 2 sources: the mothers' reports of cancers occurring in 8216 sons and daughters, and pathology-confirmed cancers and benign diagnoses self-reported by a subset of 793 daughters. RESULTS: Although statistical power is limited, our data are consistent with no overall increase of cancer in the sons or daughters of women exposed in utero to DES. Based on pathology-confirmed diagnoses reported by the daughters, we saw no association between DES and risk of benign breast disease or reproductive tract conditions. Based on 3 cases, the incidence of ovarian cancer was higher than expected in the daughters of women exposed prenatally to DES. CONCLUSIONS: Our data do not support an overall increase of cancer risk in the sons or daughters of women exposed prenatally to DES, but the number of ovarian cancer cases was greater than expected. While preliminary, this finding supports continued monitoring of these daughters.

Cancer risk in women prenatally exposed to diethylstilbestrol.

Prenatal diethylstilbestrol (DES) exposure is associated with excess risks of clear cell adenocarcinoma (CCA), and breast cancer in older women. Whether overall cancer risk is also elevated is unclear. Total and site-specific cancer risks were evaluated in the DES Combined Cohort Follow-up Study using age- and calendar-year specific standardized incidence rate ratios (SIR), and age-adjusted incidence rate ratios (RR) comparing DES exposed and unexposed women. A total of 143 and 49 cancer cases occurred in 97,831 and 34,810 person-years among the exposed and unexposed, respectively. There was no overall excess risk among exposed women when compared with external rates (SIR 1.01; 95% confidence interval [CI] 0.86-1.2). The overall RR comparing exposed with unexposed women was 1.32 (95% CI 0.94-1.8). Breast cancer risk was elevated only among women over 40 years (RR 1.83; 95% CI 1.1-3.2). The CCA SIR among exposed women was nearly 40, and the estimated attack rate through age 39 was 1.6/1,000 women. CCA incidence decreased by over 80% after age 25 when compared with 20-24 years. Excluding CCA and breast cancer, the overall RR was 1.21 (95% CI 0.74-2.0). DES was not associated with excess risks of either endometrial or ovarian cancer. These data suggest that the DES associated increase in CCA incidence remains elevated through the reproductive years. There was no consistent evidence of risk excesses for cancers other than CCA, and breast cancer in older women. Given that the population is still young, continued follow-up is necessary to assess the overall carcinogenic impact of prenatal DES exposure.

Age at natural menopause in women exposed to diethylstilbestrol in utero.

Age at natural menopause is related to several health outcomes, including cardiovascular disease and overall mortality. Age at menopause may be influenced by the number of follicles formed during gestation, suggesting that prenatal factors could influence menopausal age. Diethylstilbestrol (DES), a nonsteroidal estrogen widely prescribed during the 1950s and 1960s, is related to reproductive tract abnormalities, infertility, and vaginal cancer in prenatally exposed daughters but has not been studied in relation to age at menopause. The authors used survival analyses to estimate the risk of natural menopause in 4,210 DES-exposed versus 1,829 unexposed US women based on responses to questionnaires mailed in 1994, 1997, and 2001. DES-exposed women were 50% more likely to experience natural menopause at any given age (hazard ratio = 1.49, 95% confidence interval: 1.28, 1.74). Among women for whom dose information was complete, there were dose-response effects, with a greater than twofold risk for those exposed to >10,000 mg. The causal mechanism for earlier menopause may be related to a smaller follicle pool, more rapid follicle depletion, or changes in hormone synthesis and metabolism in DES-exposed daughters. Age at menopause has been related, albeit inconsistently, to several exposures, but, to the authors' knowledge, this is the first study to suggest that a prenatal exposure may influence reproductive lifespan.