Undescended Testicles (Cryptorchidism)

Environmental endocrine modulators and human health: an assessment of the biological evidence, 1998


Animal DES Data

The biological plausibility of a relationship between in utero exposure to exogenous estrogen and cryptorchidism is supported by animal studies. In the mouse model, following maternal DES doses of 0.1, 1.0, 2.5, 5, 10, and 100 mg/kg/d on days 9 to 16 of gestation, only the highest dose (100 mg/kg/d) produced observable reproductive tract effects, including cryptorchidism, on male offspring. The lack of effects on the male mouse reproductive tract following in utero exposure to doses of DES of less than 100 µg/kg/d may have implications for humans exposed in utero to compounds identified as environmental estrogens that have significantly less estrogenic activity than DES. If a testosterone surge is the triggering event in testicular descent, elevated estrogen levels during this critical time period may be required to offset it.

Human DES Data

There are a number of studies of sons exposed in utero, primarily to DES, in which the subsequent incidence rates of cryptorchidism have been increased compared with unexposed infants. Cryptorchidism incidence rates were assessed in 308 males whose mothers had participated 25 years earlier in a randomized double-blind study of the usefulness of DES on reducing miscarriage.The initial clinical trial had been conducted at the University of Chicago, where the DES dosing protocol was 5 mg/d starting at the seventh week of gestation, and increasing by 5 mg/d every second week, up to a maximum daily dose of 150 mg at 34 weeks. Women were enrolled in this treatment protocol no later than the 20th week of pregnancy; 95% of the women in the treatment group received total DES doses between 11,500 mg and 12,600 mg. Thus, males were exposed in utero to substantial maternal DES doses during a critical time of reproductive tract development. In the DES-exposed males, 17 of 308 reported cryptorchidism compared with one in the unexposed group. As the unexposed and DES-exposed groups were approximately the same size, the single case of cryptorchidism reported in the unexposed group may be too low, exaggerating the association with cryptorchidism in the exposed group. If, as noted above, the prevalence of cryptorchidism in the U.S. at birth is 0.8%,suggesting that approximately 2 to 3 cases of cryptorchism in the unexposed group would be expected. Even if this is correct, in utero exposure to DES still resulted in an increased incidence of cryptorchidism in male offspring.

In a large retrospective study conducted in a population drawn from the Mayo Clinic, the incidence rate of cryptorchidism at birth was 0.78% in over 14,000 male births from 1943 to 1973. Multivariate analysis provided no evidence to suggest that in utero estrogen exposure was associated with an increased incidence of cryptorchidism in male offspring. The retrospective nature of this study poses some problems due to the uncertainty surrounding patient compliance (e.g., DES doses) and the validity of diagnosis. In particular, noncompliance would tend to reduce the strength of any observed association. While acknowledging that animal studies demonstrate a cause and effect relationship between prenatal exposure to DES and cryptorchidism, Beard et al. note that, “…evidence that estrogen and/or progestin exposure causes cryptorchidism in humans is less impressive.” The studies of the Mayo Clinic cohorts are important because maternal median doses ranging from 720 to 1675 mg (with mean exposure durations of about 121 d) were extremely low, relative to total maternal doses used elsewhere (e.g., over 11,000 mg at the University of Chicago).

Other studies have investigated cryptorchidism in offspring exposed to DES in utero, but most of these fail to provide sufficient information concerning total maternal DES doses. In a study of men exposed in utero to DES in the San Francisco area, there were no differences between exposed and unexposed in any testicular parameter. The approximate total maternal DES dose was 3000 mg with an average fetal exposure duration of 23 weeks. There were three cases of cryptorchidism (in addition to other genitourinary abnormalities) in 225 men exposed in utero to DES in the Los Angeles area and one case in 111 unexposed men.

While the number of subjects in this study was small making incidence rates unstable, it is of interest that the median total maternal DES dose of 4575 mg was relatively high (mean duration of exposure of 112 d); 67% of subjects began taking DES during the first trimester.

The results of the Mayo Clinic studies, showing no increased risk of cryptorchidism among DES-exposed males, suggest that the relatively lower maternal doses used there are unlikely to cause this condition. The existence of an apparent maternal DES no effect dose for cryptorchidism challenges the biological plausibility that in utero exposure to much weaker compounds identified as environmental estrogens may be associated with cryptorchidism following in utero exposure. Because individual environmental estrogens tested to date are significantly less potent than DES, it will be important to determine whether net estrogenic activity (i.e., after accounting for total estrogenic and antiestrogenic activity) of environmental estrogens (either as dietary intake or as body burdens) would be present at sufficient concentrations to cause in utero estrogenic effects (e.g., cryptorchidism) on developing offspring similar to DES. In particular, studies comparing animal and human DES effect and no effect maternal dose levels with typical mixtures of environmental estrogens exposure levels will be critical. Because a DES dose of 100 µg/kg was the only effective maternal dose in producing cryptorchid testes in experiments with mice, it will be necessary to determine whether mixtures of typically encountered environmental estrogens have a comparable net estrogenic potency. Perhaps more importantly, because a human maternal total DES median dose of 720 mg appears to have been ineffective in producing cryptorchidism in offspring exposed in utero, it will also be necessary to determine net estrogenic potency of typically encountered mixtures of environmental estrogens.


  • Environmental endocrine modulators and human health: an assessment of the biological evidence, Critical reviews in toxicology, NCBI PubMed, PMID: 9557209, 1998.
  • Featured image civitatis.

Exogenous Estrogens and Breast Cancer : DES

Environmental endocrine modulators and human health: an assessment of the biological evidence, 1998


Maternal Exposure

Several studies have investigated breast cancer risk in women given DES or other exogenous estrogens during pregnancy. In a cohort study of 1531 women exposed to DES during pregnancy, the relative risk for breast cancer was 1.5 (CI 0.88 to 2.49).  Within the exposed group, there was also no evidence for a dose-response relationship with relative risks for breast cancer of 1.38, 1.46, and 1.29 for total DES doses of <1000 mg, 1000 to 4500 mg, and >4500 mg, respectively. The mean total DES dose in this study was 2100 mg. While there was a slight excess of breast cancer in the DES group (although not statistically significant), the authors note that this may have also been due to hormonally related reproductive difficulties in these women, which was why they were given DES.

In a study comparing the incidence of breast cancer in a cohort of 3033 women who had taken DES during pregnancy with an appropriate unexposed group, there was an increased relative risk of 1.46 (CI 1.1–1.9). Breast cancer mortality was slightly higher in the DES-exposed group (RR = 1.1), but this was not statistically significant. Because information on total DES doses used was not available, a dose-response relationship between DES and breast cancer could not be determined. The authors were unable to rule out whether the increased incidence of breast cancer was due solely to DES or some other characteristic of DES-exposed women (e.g., an underlying hormonal disorder that precipitated the use of DES). In a follow-up study of the same cohort, there was a modest, but statistically significant increase in breast cancer risk associated with exposure to DES during pregnancy (RR = 1.35). Because this follow-up study included 127 new breast cancer cases and 42,000 additional women-years of observation, in addition to controlling for previous miscarriage, the relative rate estimates are more precise than those in the earlier report. However, it did not appear that breast cancer risk associated with DES increased over time. Finally, in a study of 319 women who were part of a randomized clinical trial of DES, there was no difference in the incidence of breast cancer between DES exposed and unexposed. The mean total DES dose in this study was 11.5 g.

The data addressing increased breast cancer risk associated with DES exposure during pregnancy are equivocal. While the available data support a possible weak association between exposure to DES and increased risk of breast cancer, studies are limited by a lack of sufficient information on dose and duration and the inability to distinguish DES-induced effects from indicators for using DES (i.e., an underlying hormonal imbalance). Nevertheless, exposure to DES during pregnancy does not appear to appreciably increase the risk of breast cancer.

In Utero Exposure

It has also been hypothesized that increased maternal estrogen levels during pregnancy may be associated with an increased probability of breast cancer in daughters. However, there are limited empirical data to confirm this hypothesis. To date, there is no evidence of an association between in utero DES exposure and increased risk of breast cancer in adulthood because the relevant birth cohorts of DES offspring have not reached the age range at highest risk for breast cancer. Only indirect evidence has been used to suggest that intrauterine exposure to estrogens may be associated with subsequent increased risk of breast cancer. Correlations between endogenous serum estrogen levels during pregnancy in certain populations and breast cancer risk in the daughters may be useful in evaluating the potential association between in utero DES exposure and breast cancer. Significantly lower (i.e., 30%) serum estrogen levels in pregnancy have been reported in younger women (<20 years) compared with older women (20 to 29 years). These findings, together with evidence showing an association between later maternal age at birth and increased breast cancer risk in daughters have been used to suggest that in utero exposure to the potent, synthetic estrogen, DES, may be associated with increased breast cancer risk. However, this is entirely hypothetical and confirmation of this must await the results of studies now in progress, of women exposed in utero to DES as they reach the age of greatest breast cancer risk.


  • Environmental endocrine modulators and human health: an assessment of the biological evidence, Critical reviews in toxicology, NCBI PubMed, PMID: 9557209, 1998.
  • Featured image Samuel Zeller.

Hormonal Risk Factors for Testicular Cancer

Environmental endocrine modulators and human health: an assessment of the biological evidence, 1998


Prenatal exposure of mice to DES (100 µg/kg on days 9 to 16 of gestation) results in numerous statistically significant adverse effects on the testes and related structures, including a high percentage of cryptorchidism (91%), inflammation (29%), hyperplasia (56%), and adenocarcinoma (5%). Even though the testicular neoplasms were expressed later in life, interference with normal testicular development in utero may be necessary for their development. The adenoma carcinomas observed occurred in the rete testis, a structure connecting the testis and epididymis. Tumors of the rete testis appear to be similar in mice and humans.

Despite the animal experimental data demonstrating an association between in utero exposure to DES and subsequent testicular cancer, the human data with DES are less compelling. A number of studies have investigated the relationship between in utero exposure to DES and subsequent testicular cancer in offspring. Using the Connecticut Tumor Registry data, a case-control study of 79 males exposed to DES in utero demonstrated that such exposure did not increase the risk for testicular cancer compared with controls. Another case-control study on 273 cases of testicular cancer in northern California found no association between testicular cancer risk and in utero exposure to exogenous hormones during pregnancy (OR = 0.9).378 A case-control study of 108 cases of testicular cancer in the Los Angeles area reached a different conclusion reporting that exposure of the mother to exogenous estrogen (i.e., DES, estrogen, progestin, or estrogen in a pregnancy test) during pregnancy was a significant risk factor (RR = 8.0) for testicular cancer in the offspring. The extent of estrogen exposure in this group is somewhat uncertain because the mothers of five of the nine cases took only a single hormonal preparation as a pregnancy test. A recent review of the available data by the National Cancer Institute concluded that in utero DES exposure has not been linked to testicular cancer. However, a problem that plagues these comparisons is that, in all likelihood, most women who were exposed to DES are unaware of their exposure. Resulting exposure misclassification would tend to obscure effects.

There are several case reports of testicular seminoma in men in their late 20s who were exposed to DES in utero.  However, it is difficult to ascertain the significance of isolated cases in light of the overall lack of increased incidence of testicular cancer in DES-exposed cohorts. Because testicular cancer reaches a peak incidence rate between the ages of 30 to 35, with substantial increases starting at ages 20 to 24, one might expect that if in utero exposure to DES were a significant risk factor that more than a few isolated cases would have been reported by this time. Unlike most cancers that occur later in life, the peak incidence ages for testicular cancer suggests that sufficient time has elapsed so significant numbers of DES-exposed men are in this age range. To date, there is no significant association between in utero exposure to DES and increased incidence of testicular cancer; however, ongoing studies of the DES sons cohort may provide additonal data. On the other hand, if in utero exposure to DES were associated with increased incidence of testicular cancer after the age of 60, it would be premature to expect to see such in increase in the DES-exposed cohort. This issue can only be resolved by additional follow-up of DES-exposed cohorts as they age.


  • Environmental endocrine modulators and human health: an assessment of the biological evidence, Critical reviews in toxicology, NCBI PubMed, PMID: 9557209, 1998.
  • Featured image Jack Patrick.

Intrauterine exposure to diethylstilbestrol: long-term effects in humans

APMIS : acta pathologica, microbiologica, et immunologica Scandinavica, 2000


DES is the most carefully scrutinized EDC and its history provides valuable insights into the current evaluation of less well-studied EDCs. This review summarizes the health effects of prenatal exposure to diethylstilbestrol (DES) and emphasizes the role of DES as the first endocrine disrupting chemical (EDC).


Vaginal clear cell adenocarcinoma (CCAC), the most severe consequence of prenatal exposure to DES, affected only 0.1% of exposed females, while the far more prevalent teratogenic and reproductive effects of DES were only discovered when DES daughter were screened for CCAC. Initial studies, conducted before most DES daughters had tried to conceive, examined vaginal cancer and vaginal, cervical and uterine abnormalities. Subsequently, several controlled studies demonstrated the increased risk of adverse reproductive outcomes in DES daughters. While most DES daughters can eventually experience a live birth, this is less likely in women with genital tract abnormalities, in whom there is a two-thirds chance that each pregnancy will be unsuccessful.


In DES sons, who have been far less studied, results suggest male reproductive toxicity, but are less consistent. The importance of dose and gestational age at initial exposure are discussed, and the implications of DES findings for the evaluation of risks from current EDCs emphasized.

Because of the dramatic development of vaginal/cervical clear cell adenocarcinoma in DES daughters, an increased risk of testicular cancer in DES sons has long been postulated. However, studying this association is difficult since both the disease and the exposure are uncommon. Only two cohort studies have examined testicular cancer, one reporting a testicular teratoma and the other two germ cell cancers in the exposed and none in the unexposed. In the six case-control studies published, exposure was broadly defined, and none studied DES specifically. These studies examined testicular cancer in relation to a maternal history of any hormone medication during the pregnancy, or any drug for bleeding, spotting or threatened abortion or prevention of miscarriage. The strongest association was seen in the one study that restricted exposure to the first trimester, which reported a relative risk estimate of 8.0 (p=0.02). These case-control studies were all of low statistical power. One of the largest, with 225 cases, did not have the power to rule out a relative risk of 7.0 (assuming alpha=0.05 and beta=0.80 and a 1% exposure to DES). Thus, while no consistent pattern of testicular cancer risk is seen for prenatal hormone exposure (featured image), an increased risk of testicular cancer in association with prenatal hormone use cannot be ruled out. Prenatal exposure to DES, specifically, is currently being examined in the DES Combined Cohort Studies (DCCS), a cohort study that includes 2,000 DES sons and 2,000 controls. However, it should be remembered that CCAC occurred in only one DES-daughter per thousand. If DES caused an equally rare form of genital tract cancer in DES sons, it is unlikely to be detected in this cohort study.

Several authors have reported increased urogenital tract abnormalities in males exposed in utero to DES. In Depue, an analysis of birth outcomes from the Collaborative Perinatal Project, the (matched) relative risk for cryptorchidism and mother’s use of estrogen (estradiol or DES) was 2.80 (p=0.06). Genital tract abnormalities were studied in the Dieckmann cohort by Bibbo, Gill and and Wilcox.

Several other authors studied cohorts identified in a single hospital or city. Most of these studies found a significant excess of one or more genital tract abnormalities, including epididymal cysts, hypertrophic or undescended testis, capsular induration, hypoplastic penis or hypospadias.

In addition, several studies examined the relationship between prenatal DES exposure and semen quality. The findings were mixed, with some studies finding significantly impaired semen quality in exposed males, and others finding little or no association. Leary and colleagues examined 265 exposed and 274 unexposed men born at the Mayo Clinic. They did not find increases of genitourinary abnormalities or infertility. As noted above, the median total dose their mothers received was only 720 gms. This should be compared to median doses of 11,025 and 2,530 gms for DESAD participants with and without structural anomalies.

The data on infertility in DES sons are quite limited. Wilcox and colleagues found no impairment of fertility in their follow-up of the Dieckmann cohort. In particular, the probability of conception in 119 couples in which the man was DES-exposed did not differ from 104 couples in which the man was unexposed. While a greater excess of genital abnormalities was reported in this study for men exposed prior to week 11, fertility did not differ by week of exposure. However, as noted above, the proportion of men in the Dieckmann cohort who were exposed in very early pregnancy is quite low.

In 1980 Driscoll conducted a controlled study of perinates identified from autopsy records, using a study design similar to that used by Johnson in examining female abortuses and stillbirths with respect to adenosis (discussed above). Blinded to exposure status, Driscoll examined prostate sections from 31 exposed and 62 unexposed pregnancies. Significantly higher rates of prostate abnormalities (abnormalities of the utricle and dilated ducts) were seen in the exposed. The highest rates were in those nine perinates exposed to DES alone; 100% had both a prostatic utricle and dilated ducts with squamous metaplasia. While there have been no reports of prostate abnormalities in adults exposed to DES during fetal life, most DES sons are not yet 50 years old. Since few of these men have reached the age at which benign prostatic hyperplasia (BPH) or prostate cancer increases in frequency, prostate abnormalities in DES sons have not yet been studied and it is important that this cohort be monitored for these endpoints.

A limited number of studies have examined the hypothesis that the development of hemispheric organization and cognitive abilities in humans is influenced by prenatal hormones, and DES in particular. Reinish conducted a double blind study of ten pairs of male siblings. One was exposed to a DES dose exceeding 1000 mg and early exposure (eight of ten were exposed by gestational week ten), while the other was unexposed to any exogenous hormone. This study reported DES exposure significantly associated with reduced hemispheric laterality and lowered spatial ability.


  • Intrauterine exposure to diethylstilbestrol: long-term effects in humans, APMIS : acta pathologica, microbiologica, et immunologica Scandinavica, NCBI PubMed PMID: 11252812, 2000.
  • Featured image credit mmcapital.

Trends in Male Reproductive Health

Environmental Aspects, Reproductive Toxicology, 1998


During the past five years, several researchers have focused on recent trends of declining male reproductive health.

Almost all cancer registries in the Western World have noted a remarkable increase in testicular cancer. Thus, in Scandinavia, where the incidence of testicular cancer is particularly high, there has been a three to four-fold increase during the past 50 years. The same trend has been found among U.S. whites, although no increase has been demonstrated among Afro-Americans who generally have a very low risk of testicular cancer.

During the same period, we have several indications of decrease in semen quality – again the bulk of the data come from the Western World.

There are also data to suggest that the incidence of other genital abnormalities, including hypospadias and undescended testis are weaker.

The fact that the reported changes the reported changes in male reproductive health have occurred simultaneously within a short period of time suggests that common environmental factors are of importance.

As normal sexual differentiation, development of the gonads and normal postnatal development are essential for normal reproductive function in adulthood, it was suggested that a common foetal factor could play a part for the observed trends. Based on epidemiological evidence from studies of children of mothers who were exposed to DES (Diethylstilbestrol) in early pregnancy and experimental evidence from administration of synthetic estrogens to pregnant animals, it was hypothesised that environmental hormone disrupters, which have been demonstrated to be ubiquitously distributed, could play an aetiological role.



Are estrogens carcinogenic during development of the testes?

Many chemicals in the environment mimic the female sex hormone, estrogen, 1998

Selected Abstracts

Exposure to environmental estrogens during early fetal development was proposed by Sharpe & Skakkebaek as a potential risk factor for subsequent testicular disease, including neoplasia and poor semen quality.

To understand the mechanisms of action of estrogenic chemicals during differentiation of the male genital tract, we have studied developmental exposure to the synthetic estrogen, diethylstilboestrol (DES). While DES is a much more potent estrogen than most environmental chemicals examined, several of these compounds share some of the same properties as DES, such as a relative lack of binding to serum estrogen carrying proteins.

Prenatal exposure to DES is associated with poor semen quality, prostatic disease, cryptorchidism and testicular neoplasia in mice. A rare form of testicular cancer, rete testis carcinoma, was observed in five percent of male mice treated in utero with DES. We also demonstrated altered regulation of an estrogen responsive gene, lactotransferrin (LTF) in the seminal vesicles of treated mice, but not the controls. Likewise, LTF was irreversibly altered in the uteri of developmentally treated females; at the molecular level altered methylation of the gene appears to be involved, thus, providing a potential marker for hormonal effects during development.

The induction of permanent or “imprinted” responses during the development of a relatively estrogen-free reproductive tract cell suggests that undifferentiated targets for estrogen action may be sites for subsequent growth and differentiation defects associated with neoplasia.


  • Are estrogens carcinogenic during development of the testes?, APMIS : acta pathologica, microbiologica, et immunologica Scandinavica, NCBI PubMed, PMID: 9524585, 1998.
  • Steroidogenic cells featured image Zoe Johnston, eurekalert.

DES Incidence of Testicular Cancer : Not Enough Evidence Yet

Do Environmental Estrogens Contribute to the Decline in Male Reproductive Health ? 1995

Selected Abstracts

Testicular cancer is now the most common malignancy of young men in many countries; although it is still rare compared with the malignant diseases most prevalent in old age, the lifetime risk of developing testicular cancer now approaches 1% in Denmark. The incidence of testicular cancer has been increasing for several decades. On the basis of data from several cancer registries, increases in incidence are evident in England and Wales, Scotland, the Nordic and Baltic countries, Australia, New Zealand, and the US. The observed increase has been 2-4% per annum in men younger than age 50 and has occurred in those between ages 20 and 45 years, in whom the incidence of testicular cancer is highest. Marked differences in race and in geographical areas exist; e.g., the incidence in Denmark is fourfold higher than in Finland, and whites are three fold more susceptible to this disease than are blacks in the US. We do not know the etiology of testicular cancer and therefore cannot prevent the disease.

The structural abnormalities of the reproductive organs more frequently reported in males exposed to DES than in controls include meatal stenosis, hypospadias, epididymal cysts, and testicular abnormalities.

Not enough evidence exists to indicate an increased risk of testicular cancer in men exposed to DES, but the case-control studies thus far performed include major design problems.

  • Hormone treatment may have been initiated at variable times during pregnancy; therefore, the presumed critical period when adverse effects of estrogens might occur may have been missed in some of these studies.
  • Furthermore, the exact prescribed hormone and the dose are often not remembered and therefore some women may have been treated with only progesterone.
  • Also, the number of cases has been too small to determine whether a substantial difference truly exists, and recall bias may also be present.


  • Full study (free access) Do environmental estrogens contribute to the decline in male reproductive health?, Clinical chemistry, NCBI PubMed, PMID: 7497651, 1995.
  • Trends in age-standardized (world standard population) incidence rates of testicular cancer featured image aaccjnls.

DES and tumors in the area of the rete testis

Cellular and molecular effects of developmental exposure to diethylstilbestrol: implications for other environmental estrogens, 1995


Studies with the potent synthetic estrogen diethylstilbestrol (DES) suggest that exogenous estrogen exposure during critical stages of development can result in permanent cellular and molecular alterations in the exposed organism. (DES-linked) abnormalities include breast cancer, endometriosis, fibroids, and uterine adenocarcinoma in females, as well as alterations in sex differentiation, decreased sperm concentrations, benign prostatic hyperplasia, prostatic cancer, testicular cancer, and reproductive problems in males.

Testis Cancer

The identification of tumors in the area of the rete testis is exceptionally rare; in fact, rete testis tumors have been reported infrequently in the clinical literature and in experimental animals. It is interesting that treatment of pregnant CD-1 mice with DES (100 pg/kg) resulted in rete testis adenocarcinoma in 5% of their male offspring. The high incidence of retained testis in mice (92%) following prenatal DES exposure and the occurrence of the rare rete testis adenocarcinoma raise the possibility of an association between prenatal DES exposure and the incidence of cryptorchidism and rete testis cancer.

Although cryptorchidism resulted in decreased or lack of spermatogenesis in male mice, inactivity alone could not account for the higher prevalence of rete cancer because several of the mice with the tumor had spermatogenesis occurring in the same testis. In addition to rete cancer, increased incidence of lesions of the corpus testis and Mullerian duct remnants were also seen. Since these lesions were observed in high-dose DES males, males receiving lower DES doses are being followed for increased cancer risk, although their fertility was not significantly affected.


  • Cellular and molecular effects of developmental exposure to diethylstilbestrol: implications for other environmental estrogens, Environmental health perspectives, NCBI PubMed, PMC1518878, 1995.
  • Featured image pexels.

A randomized double-blind controlled trial of the value of stilboestrol therapy in pregnancy

Long-term follow-up of mothers and their offspring, 1983


In the early 1950s, a randomized, double-blind, controlled trial of the value of prophylactic stilboestrol therapy given antenatally to reduce the incidence of late pregnancy toxaemia and to improve perinatal mortality was conducted at University College Hospital, London.

Women expecting their first baby were allocated to one or other of two groups. Those in the stilboestrol group started treatment at the 12th week of pregnancy on average and received a mean dose of about 11.5 g of the drug while those in the control group received placebo tablets.

In spite of the fact that the original trial documentation was lost, it was possible to be fairly certain which was the treated group and follow-up data from 650 mothers and 660 offspring were obtained from death certificates, cancer registrations and questionnaires sent to general practitioners.

We found no indication of any harmful long-term effect of stilboestrol exposure during pregnancy on the mothers–in particular 10 out of 331 women in the untreated group and 9 out of 319 women in the treated group were found to have developed breast cancer.

Amongst the daughters, those in the treated group suffered an excess of minor benign lesions of the cervix uteri and an excess (not statistically significant) of unfavourable pregnancy outcomes. None of the daughters had developed clear cell adenocarcinoma of the vagina or cervix uteri.

Amongst the sons, we discovered no evidence of any significant excess of genital tract disorders or of impaired reproductive performance in the treated group but one son developed a (fatal) teratoma of the testis.

Unexpectedly, psychiatric disease (especially depression and anxiety) was reported by general practitioners about twice as often in the treated group offspring (sons and daughters) as in the untreated group. This result cannot be due to bias, and is unlikely to be due to confounding or chance, and may thus represent an adverse effect of exposure to stilboestrol in utero.


  • A randomized double-blind controlled trial of the value of stilboestrol therapy in pregnancy: long-term follow-up of mothers and their offspring, British journal of obstetrics and gynaecology, NCBI PubMed, PMID: 6357269, 1983.
  • University College Hospital, London featured image wellcomecollection.

Testicular cancer development in DES Sons

Diethylstilbestrol revisited: a review of the long-term health effects, 1995


The association between in utero DES exposure and the development of testicular cancer is controversial.

An increased risk for testicular tumors was observed in studies of mice exposed to DES, and an increased incidence of cryptorchidism, a strong risk factor for testicular cancer, has been observed in DES sons.

Several cases of testicular cancer in men exposed to DES have been reported , and two cohort studies have each reported one case of testicular teratoma.

The findings from six case-control studies that have examined the association between DES exposure in utero (or exposure to any exogenous hormone) and testicular cancer have been mixed.

On the basis of interviews with mothers of 79 men with testicular cancer that was diagnosed between 1972 and 1974 and interviews with 79 matched controls, Henderson and associates found a relative risk of 5.0 (P = 0.11; CI not given) for any hormone use during the pregnancy.

Schottenfeld and colleagues reported that drug use was associated with a relative risk of 1.96 (CI, 0.8 to 4.3) for bleeding, spotting, or threatened miscarriage during the pregnancy; however, 45% of case mothers and 63% of control mothers could not recall the specific drug taken.

In a study of 108 cases diagnosed in California between 1973 and 1979 and 108 matched controls, Depue and coworkers found that any exogenous hormone use during the first trimester was associated with an eightfold increased relative risk for testicular cancer; however, only two case mothers reported receiving DES.

In contrast to these suggestive studies, three studies have found no effects of DES exposure on the risk for testicular cancer.

Moss and colleagues reported an odds ratio of 0.9 for use of exogenous hormones during pregnancy; DES exposure, reported by four case mothers and two control mothers, resulted in a nonsignificant odds ratio of 2.0.

Similarly, Brown and associates found an odds ratio of 0.8 for hormone use, and Gershman and Stolley) reported an odds ratio of 0.8 for the receipt of drugs used to prevent miscarriage.

Problems common to these studies include the lack of documentation to confirm exposure and the difficulty of maternal recall of exposures during pregnancy. The relatively young age of the cohort at the time of study could also have precluded detection of an increased risk for testicular cancer, which in the general population peaks in the fourth decade of life.

Although these studies probably rule out a high level of risk, they are based on fairly small numbers, which may preclude the detection of a low to moderate increase in risk associated with DES. No other cancer sites in men have been implicated.


  • Diethylstilbestrol revisited: a review of the long-term health effects, Annals of internal medicine, NCBI PubMed, PMID: 7717601, 1995.
  • Featured image Jordan Whitfield.